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# What is the empirical formula for BaH1o ?BAHsBzHaBHsBaH1oBzHs

###### Question:

What is the empirical formula for BaH1o ? BAHs BzHa BHs BaH1o BzHs

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# Synopsis: Discrepancy in Neutron Lifetime Still Unresolved

Precision measurements of the neutron lifetime differ by about 8 seconds.

Outside of the nucleus, the proton remains stable for at least ${10}^{34}$ years, but an isolated neutron survives just $15$ minutes before it decays into a proton, electron, and an antineutrino. Astrophysicists rely on a precise value of the free neutron lifetime to calculate the rate of nucleosynthesis during the big bang, while particle physicists use it to constrain fundamental parameters of the standard model. Yet measured lifetimes have varied by about a percent, depending on the experimental technique. As reported in Physical Review Letters, the latest refinement of the neutron lifetime in one type of experiment has left this discrepancy unresolved.

Researchers have relied on two experimental strategies to measure the neutron lifetime. In the “bottle” method, low-energy neutrons are confined in a trap constructed from magnetic fields or wall materials like beryllium that reflect neutrons. The neutron lifetime can be determined by simply counting the number of particles that survive after a fixed storage time. The alternative is the “in-beam” method, in which a beam of neutrons with a precisely known flux travels through a well-defined volume, and the lifetime is determined by counting the number of decay products.

The two types of experiments give a neutron lifetime that differs by $8$ seconds (or $2.6$ standard deviations)—a discrepancy that researchers have chalked up to unresolved systematic errors. As a first step, scientists working at the NIST Center for Neutron Research in Gaithersburg, Maryland, have now refined their earlier in-beam measurement from 2005 with a more accurate value of the neutron flux (the largest uncertainty in the original experiment) by recalibrating their original neutron detector. The NIST researchers now report an in-beam neutron lifetime of $887.7±2.3\phantom{\rule{0.333em}{0ex}}\text{s}$, in agreement with their previously measured value, but raising the significance of the discrepancy to $3.8$ standard deviations. – Kevin Dusling

Correction (2 December 2013): Paragraph 3, sentence 1, “2.9 standard deviations” changed to “2.6 standard deviations.”

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Lemma 15.115.13. Let $A$ be a ring which contains a primitive $p$th root of unity $\zeta$. Set $w = 1 - \zeta$. Then

$P(z) = \frac{(1 + wz)^ p - 1}{w^ p} = z^ p - z + \sum \nolimits _{0 < i < p} a_ i z^ i$

is an element of $A[z]$ and in fact $a_ i \in (w)$. Moreover, we have

$P(z_1 + z_2 + w z_1 z_2) = P(z_1) + P(z_2) + w^ p P(z_1) P(z_2)$

in the polynomial ring $A[z_1, z_2]$.

Proof. It suffices to prove this when

$A = \mathbf{Z}[\zeta ] = \mathbf{Z}[x]/(x^{p - 1} + \ldots + x + 1)$

is the ring of integers of the cyclotomic field. The polynomial identity $t^ p - 1 = (t - 1)(t - \zeta ) \ldots (t - \zeta ^{p - 1})$ (which is proved by looking at the roots on both sides) shows that $t^{p - 1} + \ldots + t + 1 = (t - \zeta ) \ldots (t - \zeta ^{p - 1})$. Substituting $t = 1$ we obtain $p = (1 - \zeta )(1 - \zeta ^2) \ldots (1 - \zeta ^{p - 1})$. The maximal ideal $(p, w) = (w)$ is the unique prime ideal of $A$ lying over $p$ (as fields of characteristic $p$ do not have nontrivial $p$th roots of $1$). It follows that $p = u w^{p - 1}$ for some unit $u$. This implies that

$a_ i = \frac{1}{p} {p \choose i} u w^{i - 1}$

for $p > i > 1$ and $- 1 + a_1 = pw/w^ p = u$. Since $P(-1) = 0$ we see that $0 = (-1)^ p - u$ modulo $(w)$. Hence $a_1 \in (w)$ and the proof if the first part is done. The second part follows from a direct computation we omit. $\square$

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It is currently 13 Dec 2018, 16:59

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# In Cytherea Corporation, each employee was given an interper

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In Cytherea Corporation, each employee was given an interper [#permalink]  04 Dec 2017, 03:05
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In Cytherea Corporation, each employee was given an interpersonal assessment with a score from 0 to 60. Te average score among all male employees was 35, and the average score for all employees was 39. If Cytherea Corporation has 40 male employees and 10 female employees, what was the average score among all female employees?

A. 40
B. 43
C. 47
D. 51
E. 55

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Re: In Cytherea Corporation, each employee was given an interper [#permalink]  04 Dec 2017, 05:51
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The standard, mathematical approach (should take not more than a minute, quicker if you're good with mental math):

Total score of the male employees = 35 * 40
Total score of the female employees = x * 10

$$Overall\,average = \frac{total\,score\,of\,males\,+\,total\,score\,of\,females}{total\,number\,of\,employees}$$

$$39 = \frac{35\,*\,40 + x\,*\,10}{50}$$

Divide the equation by 10,

$$39 * 5 = 35 * 4 + x$$

$$x = 39 * 5 - 35 * 4$$

$$x = 55$$

Alternatively, using a higher level of logic and reduced math: The mean of all males is 35. The mean of all employees is 39 (this does not mean the mean of all females is 43 because the number of females is not the same as that of males). This difference of 4 would equate to the same difference from the mean female score (let's say y). The weighted difference for males is 4 * 40. But we have 10 female employees, so 4 * 40 = 10 * x where x is the additional female score. It turns out to be 16, so the mean female score is 39 + 16 = 55.
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# Solved (Free): In a history class there are 25 freshman, 21 sophomores, and 18 juniors. If the freshman averaged 81 on an examination, the sophomores averaged 84

#### ByDr. Raju Chaudhari

May 31, 2021

In a history class there are 25 freshman, 21 sophomores, and 18 juniors. If the freshman averaged 81 on an examination, the sophomores averaged 84, and the juniors averaged 72, find the mean grade for the entire class. (round to the tenths, if necessary)

#### Solution

Given that $n_1=25$ (Number of freshman), $n_2= 21$ (number of sophomores), $n_3=18$ (number of juniors).

$\overline{x}_1=81$ average of freshman in an examination, $\overline{x}_2=84$ average of sophomores in an examination and $\overline{x}_3=72$ average of juniors in an examination.

The mean grade for the entire class is

 \begin{aligned} \overline{x} &=\frac{n_1\overline{x}_1+n_2\overline{x}_2+n_3\overline{x}_3}{n_1+n_2+n_3}\\ &=\frac{25\times 81+21\times 84+18\times 72}{25+21+18}\\ &=\frac{5085}{64}\\ &=79 \end{aligned}

Thus the mean grade for the entire class is $79$.


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# lab00 : Getting Started

lab00 true Getting Started Tue 01/08 01:00PM Fri 01/11 05:00PM

# Introduction

This lab is an introduction to Python programming using the Linux Computers in Phelps 3525 and CSIL. You will write your first Python program that will print a specific text output on your computer display. The TAs in the lab are there to assist you.

## Goals for this lab

By the time you have completed this lab, you should be able to:

• use the computers in Phelps 3525 (and other labs like CSIL) to do basic things such as:
• perform basic management of directories and files
• create Python progams in IDLE
• submit an assignment using the gradescope system

This assignment is designed to make sure you are comfortable working in the computing environment and know how to submit your work. It is mostly about mechanics, not concepts. As a result, this assignment is not particularly intellectually challenging. Future labs will require quite a bit more thought!

# Step by Step Instructions

## Step 1: Verify your College of Engineering Account(s)

The Gauchospace message that welcomed you to the course invited you to create a College of Engineering account (also known as a ECI account, or a CSIL account) at this link:

https://accounts.engr.ucsb.edu/create/

We hope you did that—if so, you should be able to use that account to login on the computers in Phelps 3525, as well as the computers in the CSIL lab. If you ever forget the password to your ECI/CSIL account, you can reset it here:

https://accounts.engr.ucsb.edu/maintain/

The CSIL lab, by the way, is on the ground floor of Harold Frank Hall. The glass front doors of Harold Frank Hall look out towards the ocean. Stand just outside those doors with your back towards the ocean. The doors to the CSIL lab are just on your right. (If you can’t look over your shoulder and see an great big tree, with the ocean just behind it, you are on the wrong side of the building.) Hours vary–its open almost all the time during the regular school year

## Step 2: Bring up a “terminal”

On the Linux systems, there are a lot of things we can do with pointing and clicking with the mouse, just like on Windows or Mac. But there are also many things we can only do with the command line, or can do more easily with the command line.

So, one of the first steps will often be to bring up a “Terminal” window—a window that gives us access to the Linux “command line”.

Here’s how:

• Find the Applications Menu at the top left of the screen.
• Select System Tools, then Terminal (the icon should look like the image shown at right).
• A Terminal Window should pop up.

## Step 3: Create some directories

At the command prompt, we are going to type several commands to create folders (called "directories") on Linux in which you can store your programs.The commands are shown in the box below—but first, a little explanation.

Each of the cd commands shown below is a command to "change directory"—that is to move into a different folder on the hard drive.

• When you type cd by itself, it takes you to your ‘home directory’.
• cd followed by a directory name (e.g. cd cs8) moves you into a directory under the current one

Each of the mkdir commands "makes a new directory" (i.e. a new folder).

• For example, mkdir cs8 creates a new directory called cs8 inside the current directory.

Each of the pwd commands "prints the working directory", i.e. it tells you where you are on the hard drive.

• Your home directory is something like /cs/student/jsmith or /engr/student/mdiaz
• Under that, you might have a directory cs8—that would show up as /cs/student/jsmith/cs8, or /engr/student/mdiaz/cs8

At the command prompt, type each of these commands. What you type is shown in bold. You should get back exactly the output shown, (except that the part in italics may be different—each user will have something different show up there.)

NOTE: your prompt may not be exactly like the one shown here. Instead of -bash-4.2$, you might have something like [cgaucho@cstl-15 ~]$ . The cgaucho here is your username, the cstl-15 is where you are logged in, and the ~ is your current directory. Don’t be distracted by this detail.

-bash-4.2$cd -bash-4.2$ pwd
-bash-4.2$mkdir cs8 -bash-4.2$ cd cs8
-bash-4.2$pwd /cs/student/yourusername/cs8 -bash-4.2$ mkdir lab00
-bash-4.2$cd lab00 -bash-4.2$ pwd
-bash-4.2$cd -bash-4.2$ pwd

## Step 4: Checking if it worked

To see if it worked, you can use the file manager on the desktop. Drag any windows that might be covering up the "Home" icon on your desktop—it should be near the upper left hand corner of the screen. When you double click on this icon, it will bring up your home directory. You should see inside a folder called cs8. If you double click on that, you should see inside of it, a folder called lab00.

Note that you could also use mouse clicks and menu options to create these folders, instead of the command line. If you have trouble with the command line, then for today, it is ok to do it that way.

Eventually, though, we want you to learn some of the Unix commands also—the reasons it is important to know both will become more clear as you move deeper into the study of programming and Computer Science.

## Step 5: Bring up the program called IDLE

The preliminaries are done—now we are ready to start saving files for Python!

IDLE is a piece of software that you use to interact with the Python programming language. As we are using Python version 3 in this class, we also use IDLE version 3.

Type the following at the command prompt:

-bash-4.2\$ idle3

The window that appears should have the Python Command prompt (>>>) in it.

• This is sometimes called the "Python Command Prompt" window.
• This is also called the "Python Shell" window.

When you have the IDLE window up, you are ready for the next step.

## Step 6: Save a file in IDLE

In IDLE, select “File=>New File” to open a new “untitled” window for Python code.

When it comes up, click and drag the window by its title bar over to the right of your Python Shell window.

For this lab, there is one goal: write a Python 3 program that prints the string Hello, World! as its output.

In this sense, we are following a long tradition: for more than 40 years it has been a tradition to make printing Hello, World! be the first thing you do when learning a new programming language.

In Python 3, this program is very short. It looks like this:

print ('Hello, World!')

We will save the file under the name hello.py—it is very important that is has exactly that name, or the gradescope system will not run your program correctly.

That’s it! Now, you can also add, on the first line, a comment with your name, and information about the course, for example:

# Chris Gaucho, for CMPSC 8, Winter 2019
print ('Hello, World!')

You are encouraged to do that, because it helps someone looking at your code know that you wrote it. But, other than that, it isn’t necessary. In general, in computer programming, a comment is something that is intended only for human readers of the code, and is otherwise “ignored by the system”. Nearly every programming language has some way to express comments, though the exact rules for formatting of comments–that is, the syntax of comments–differs from one language to another.

In Python, a # starts a comment. Everything from the # to the end of that line is part of the comment.

Enter this program in IDLE, then save it under the name hello.py

## Step 7: Running your program.

To run your program, select the “Run=>Run Module” option from the menu. You should see the “Hello World!” message.

I’ll demonstrate the use of Idle in lecture, since its much easier to just follow along than to try to explain everything in a text document. If you need a further demonstration, you can find one on YouTube. For example: This video starting at 4:53 (That video is for Python 3.1, but the stuff shown in the video is the same across all versions of Python 3.x).

Next, we’ll try submitting our program to Gradescope. You’ll get some immediate feedback on whether you did it properly.

If you are registered for the course, you are should also be registered at Gradescope.com (via your @umail.ucsb.edu account) Look in your @umail account for an email from the Gradescope system inviting you to create a password. Follow the instructions to set your password; then you should see “CMPSC 8” in your courses for this term.

The lab assignment “Lab00” should appear in your Gradescope dashboard under CMPSC 8. If you haven’t submitted anything for this assignment yet, Gradescope will prompt you to upload your files. This prompt is shown below:

You either can navigate to your file(s) or “drag-and-drop” them into the “Submit Programming Assignment” window.

After you submit something on Gradescope, you will have access to the “Autograder Results” page. There is a “Resubmit” button on the bottom right that will allow you to update the files for your submission. For this lab, if everything is correct, you’ll see a successful submission passing all of the autograder tests shown below.

If the tests don’t pass, you may get some error message that may or may not be obvious at this point. Don’t worry - if the tests didn’t pass, take a minute to think if your print statement is EXACTLY like stated in the lab instructions (including the same capitalization, spaces, punctuation, etc.) and the file name is EXACTLY hello.py. If your tests didn’t pass and you’re still not sure why you’re getting the error, feel free to ask one of the course helpers.

## Final Step: Log Out

Actually, this is the final step of every lab, but we probably won’t remind you again after this one. In fact, you should do this every time you walk away from a lab computer, either in Phelps 3525 or CSIL. Here’s how:

• Find the System Menu at the top of the screen.
• Select Log Out


text:
## 4.2 Index and Summarize

Let’s go back to the example grades_2020() data defined before:

grades_2020()
Sally 1.0
Bob 5.0
Alice 8.5
Hank 4.0

To retrieve a vector for name, we can access the DataFrame with the ., as we did previously with structs in Section 3:

function names_grades1()
df.name
end
names_grades1()
["Sally", "Bob", "Alice", "Hank"]

or we can index a DataFrame much like an Array with symbols and special characters. The second index is the column indexing:

function names_grades2()
df[!, :name]
end
names_grades2()
["Sally", "Bob", "Alice", "Hank"]

Note that df.name is exactly the same as df[!, :name], which you can verify yourself by doing:

julia> df = DataFrame(id=[1]);

julia> @edit df.name

In both cases, it gives you the column :name. There also exists df[:, :name] which copies the column :name. In most cases, df[!, :name] is the best bet since it is more versatile and does an in-place modification.

For any row, say the second row, we can use the first index as row indexing:

df = grades_2020()
df[2, :]
Bob 5.0

or create a function to give us any row i we want:

function grade_2020(i::Int)
df[i, :]
end
grade_2020(2)
Bob 5.0

We can also get only names for the first 2 rows using slicing (again similar to an Array):

grades_indexing(df) = df[1:2, :name]
grades_indexing(grades_2020())
["Sally", "Bob"]

If we assume that all names in the table are unique, we can also write a function to obtain the grade for a person via their name. To do so, we convert the table back to one of Julia’s basic data structures (see Section 3.3) which is capable of creating mappings, namely Dicts:

function grade_2020(name::String)
dic[name]
end
grade_2020("Bob")
5.0

which works because zip loops through df.name and df.grade_2020 at the same time like a “zipper”:

df = grades_2020()
collect(zip(df.name, df.grade_2020))
("Sally", 1.0)
("Bob", 5.0)
("Alice", 8.5)
("Hank", 4.0)

However, converting a DataFrame to a Dict is only useful when the elements are unique. Generally that is not the case and that’s why we need to learn how to filter a DataFrame.

CC BY-NC-SA 4.0 Jose Storopoli, Rik Huijzer, Lazaro Alonso


text:
# normlms

(Removed) Construct normalized least mean square (LMS) adaptive algorithm object

normlms has been removed. Consider using `comm.LinearEqualizer` or `comm.DecisionFeedback` instead.

## Syntax

```alg = normlms(stepsize) alg = normlms(stepsize,bias) ```

## Description

The `normlms` function creates an adaptive algorithm object that you can use with the `lineareq` function or `dfe` function to create an equalizer object. You can then use the equalizer object with the `equalize` function to equalize a signal. To learn more about the process for equalizing a signal, see Equalization.

`alg = normlms(stepsize)` constructs an adaptive algorithm object based on the normalized least mean square (LMS) algorithm with a step size of `stepsize` and a bias parameter of zero.

`alg = normlms(stepsize,bias)` sets the bias parameter of the normalized LMS algorithm. `bias` must be between 0 and 1. The algorithm uses the bias parameter to overcome difficulties when the algorithm's input signal is small.

### Properties

The table below describes the properties of the normalized LMS adaptive algorithm object. To learn how to view or change the values of an adaptive algorithm object, see Equalization.

PropertyDescription
`AlgType`Fixed value, `'Normalized LMS'`
`StepSize`LMS step size parameter, a nonnegative real number
`LeakageFactor`LMS leakage factor, a real number between 0 and 1. A value of 1 corresponds to a conventional weight update algorithm, while a value of 0 corresponds to a memoryless update algorithm.
`Bias`Normalized LMS bias parameter, a nonnegative real number

## Examples

collapse all

This example configures the recommended `comm.LinearEqualizer` System object™ and the legacy `lineareq` feature with comparable settings.

Initialize Variables and Supporting Objects

```d = randi([0 3],1000,1); x = pskmod(d,4,pi/4); r = awgn(x,25); sps = 2; %samples per symbol for oversampled cases nTaps = 6; txFilter = comm.RaisedCosineTransmitFilter('FilterSpanInSymbols',nTaps, ... 'OutputSamplesPerSymbol',4); rxFilter = comm.RaisedCosineReceiveFilter('FilterSpanInSymbols',nTaps, ... 'InputSamplesPerSymbol',4,'DecimationFactor',2); x2 = txFilter(x); r2 = rxFilter(awgn(x2,25,0.5)); filterDelay = txFilter.FilterSpanInSymbols/2 + ... rxFilter.FilterSpanInSymbols/2; % Total filter delay in symbols```

To compare the equalized output, plot the constellations using code such as:

```% plot(yNew,'*') % hold on % plot(yOld,'o') % hold off; legend('New Eq','Old Eq'); grid on```

Use LMS Algorithm with Linear Equalizer

Configure `lineareq` and `comm.LinearEqualizer` objects with comparable settings. The `LeakageFactor` property has been removed from LMS algorithm. The `comm.LinearEqualizer` System object™ assumes that leakage factor is always 1.

`eqOld = lineareq(5,lms(0.05),pskmod(0:3,4,pi/4))`
```eqOld = EqType: 'Linear Equalizer' AlgType: 'LMS' nWeights: 5 nSampPerSym: 1 RefTap: 1 SigConst: [0.7071 + 0.7071i -0.7071 + 0.7071i -0.7071 - 0.7071i 0.7071 - 0.7071i] StepSize: 0.0500 LeakageFactor: 1 Weights: [0 0 0 0 0] WeightInputs: [0 0 0 0 0] ResetBeforeFiltering: 1 NumSamplesProcessed: 0 ```
```eqNew = comm.LinearEqualizer('NumTaps',5,'Algorithm','LMS','StepSize',0.05, ... 'Constellation',pskmod(0:3,4,pi/4),'ReferenceTap',1)```
```eqNew = comm.LinearEqualizer with properties: Algorithm: 'LMS' NumTaps: 5 StepSize: 0.0500 Constellation: [0.7071 + 0.7071i -0.7071 + 0.7071i -0.7071 - 0.7071i 0.7071 - 0.7071i] ReferenceTap: 1 InputDelay: 0 InputSamplesPerSymbol: 1 TrainingFlagInputPort: false AdaptAfterTraining: true InitialWeightsSource: 'Auto' WeightUpdatePeriod: 1```

Call the equalizers.

```yOld = equalize(eqOld,r); yNew = eqNew(r);```

Use Linear Equalizers Considering Signal Delays

Configure `lineareq` and `comm.LinearEqualizer` objects with comparable settings. The transmit and receive filters result in a signal delay between the transit and receive signals. Account for this delay by setting the `RefTap` property of the `lineareq` to a value close to the delay value in samples. Additionally, `nWeights` must be set to a value greater than `RefTap`.

```eqOld = lineareq(filterDelay*sps+4,lms(0.01),pskmod(0:3,4,pi/4),sps); eqOld.RefTap = filterDelay*sps+1 % Adjust to synchronize with delayed signal ```
```eqOld = EqType: 'Linear Equalizer' AlgType: 'LMS' nWeights: 16 nSampPerSym: 2 RefTap: 13 SigConst: [0.7071 + 0.7071i -0.7071 + 0.7071i -0.7071 - 0.7071i 0.7071 - 0.7071i] StepSize: 0.0100 LeakageFactor: 1 Weights: [0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0] WeightInputs: [0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0] ResetBeforeFiltering: 1 NumSamplesProcessed: 0 ```

```eqNew = comm.LinearEqualizer('NumTaps',16,'Algorithm','LMS','StepSize',0.01, ... 'Constellation',pskmod(0:3,4,pi/4),'InputSamplesPerSymbol',sps, ... 'ReferenceTap',filterDelay*sps+1,'InputDelay',0)```
```eqNew = comm.LinearEqualizer with properties: Algorithm: 'LMS' NumTaps: 16 StepSize: 0.0100 Constellation: [0.7071 + 0.7071i -0.7071 + 0.7071i -0.7071 - 0.7071i 0.7071 - 0.7071i] ReferenceTap: 13 InputDelay: 0 InputSamplesPerSymbol: 2 TrainingFlagInputPort: false AdaptAfterTraining: true InitialWeightsSource: 'Auto' WeightUpdatePeriod: 1```

Call the equalizers. When `ResetBeforeFiltering` is set to `true`, each call of the `equalize` object resets the equalizer. To get the equivalent behavior call `reset` after each call of the `comm.LinearEqualizer` object.

```yOld1 = equalize(eqOld,r,x(1:100)); yOld2 = equalize(eqOld,r,x(1:100)); yNew1 = eqNew(r,x(1:100)); reset(eqNew) yNew2 = eqNew(r,x(1:100));```

In the `comm.LinearEqualizer` object, `InputDelay` is used to synchronize with the delayed signal. `NumTaps` and `ReferenceTap` are independent of delay value. We can reduce the number of taps by utilizing the `InputDelay` to synchronize instead of reference tap. Reducing the number of taps also reduces equalizer self noise.

```eqNew = comm.LinearEqualizer('NumTaps',11,'Algorithm','LMS','StepSize',0.01, ... 'Constellation',pskmod(0:3,4,pi/4),'InputSamplesPerSymbol',sps, ... 'ReferenceTap',6,'InputDelay',filterDelay*sps)```
```eqNew = comm.LinearEqualizer with properties: Algorithm: 'LMS' NumTaps: 11 StepSize: 0.0100 Constellation: [0.7071 + 0.7071i -0.7071 + 0.7071i -0.7071 - 0.7071i 0.7071 - 0.7071i] ReferenceTap: 6 InputDelay: 12 InputSamplesPerSymbol: 2 TrainingFlagInputPort: false AdaptAfterTraining: true InitialWeightsSource: 'Auto' WeightUpdatePeriod: 1```

```yNew1 = eqNew(r2,x(1:100)); reset(eqNew) yNew2 = eqNew(r2,x(1:100));```

## Algorithms

Referring to the schematics presented in Equalization, define w as the vector of all weights wi and define u as the vector of all inputs ui. Based on the current set of weights, w, this adaptive algorithm creates the new set of weights given by

`$\left(\text{LeakageFactor}\right)w+\frac{\left(\text{StepSize}\right){u}^{*}e}{{u}^{H}u+\text{Bias}}$`

where the * operator denotes the complex conjugate and H denotes the Hermitian transpose.

## References

[1] Farhang-Boroujeny, B., Adaptive Filters: Theory and Applications, Chichester, England, John Wiley & Sons, 1998.

## Version History

Introduced before R2006a

expand all

Errors starting in R2022a


text: P: 290 1. The problem statement, all variables and given/known data Applying the method of Evjen calculate Madelungovu constant of infinitely long series of alternately opposite charged ions. Show that summarize by the Evjen cells gives the value Madelung constant $$A_n$$ whose deviation from actual value $$A$$ is less than $$\frac{1}{n^2}$$ 2. Relevant equations Madelung constant Madelung constant for the infinite number of ions alternately changing signs $$A=2(1-\frac{1}{2}+\frac{1}{3}-\frac{1}{4}+...)=2ln2$$ 3. The attempt at a solution Evjen method is method in which we look in neutral structures. So I think that first neutral structure is one whole ion and two neighbours cut in half. And second neutral structure is all other ions. Is it than Madelung constant for first neutral structure $$(A)_I=2\cdot 0,5=1$$ and for second neutral structure $$(A)_{II}=2(0,5-\frac{1}{2}+\frac{1}{3}-...)$$ And $$A_n=(A)_I+(A)_{II}$$ But where I have $$n$$ in here? 1. The problem statement, all variables and given/known data 2. Relevant equations 3. The attempt at a solution


text:
Sumários

Teste 2

15 Dezembro 2017, 10:00 José Félix Gomes da Costa

TESTE 2.

R and ZPP

13 Dezembro 2017, 16:00 José Félix Gomes da Costa

Class R. Proof that the sets in R can be decided by bounded error polynomial time probabilistic Turing machines with error probability (for probabilistic accepted words) approaching exponentially to 0 as time goes polynomially to infinity.

Proof (by padding and self-reducibility of SAT) that if NP is included in BPP, then NP = R.

Class ZPP. That ZPP = R \cap co-R.

Monte Carlo vs. Las Vegas.

Probabilistic Turing machines

6 Dezembro 2017, 16:00 José Félix Gomes da Costa

Class PP. Structural relations between NP, co-NP, PP and PSPACE. Closure of PP under complement. The intersection problem in PP.

Classe BPP. Proof hat the sets in BPP can be decided by bounded error polynomial time probabilistic Turing machines with error probability exponentially approaching 0 as time goes polynomialy to infinity.

Class R. Proof that the sets in R can be decided by bounded error polynomial time probabilistic Turing machines with error probability (for probabilistic accepted words) approaching exponentially to 0 as time goes polynomialy to infinity.

Examples of R algorithms (Monte Carlo).

Polynomial Hierarchy

29 Novembro 2017, 16:00 José Félix Gomes da Costa

The polynomial hierarchy.

Polynomial time hierarchy by means of bounded quantification. Alternation theorem.

Collapse theorems.

Oracle Turing machines

24 Novembro 2017, 10:00 José Félix Gomes da Costa

Turing reduction in polynomial time. Characterization. Example: MAXCLIQUE <= CLIQUE.

Some results on relative computation. Example theorem: If T is a tally set and DEXT(T) = DEXT, than T \in P.

Equivalence between closure under complementation and closure under Turing reduction for some complexity classes, such like NP and co-NP.

The open problem NP =/= co-NP.


text:
# Preprints

 2019-02-2511:02 [IMPULSE-2019-00107] Preprint et al Reciprocal space mapping of the magnetic order in epitaxial MnSi thin films We report grazing incidence small angle neutron scattering (GISANS) and complementary off-specular neutron reflectometry (OSR) of the magnetic order in a single-crystalline epitaxial MnSi film on Si(111) in the thick film limit. Providing a means of direct reciprocal space mapping, GISANS and OSR reveal a magnetic modulation perpendicular to the films under magnetic fields parallel and perpendicular to the film, where additional polarized neutron reflectometry (PNR) and magnetization measurements are in excellent agreement with the literature [...] External link: Fulltext 2019-01-2216:03 [IMPULSE-2019-00057] Preprint et al Interplay of Itinerant and Localized Spin Fluctuations in the Ferromagnetic Superconductor UGe$_2$ Microscopic coexistence of ferromagnetism and unconventional superconductivity renders UGe$_2$ a candidate for spin-triplet superconductivity. To avoid pair-breaking, spin-triplet superconductivity is mediated by longitudinal spin fluctuations promoted by magnetic Ising anisotropy. [...] 2018-04-2812:37 [FZJ-2018-02674] Preprint et al Do neutrons publish? a neutron publication survey 2005 - 2015 External links: OpenAccess; OpenAccess; OpenAccess; OpenAccess; OpenAccess; OpenAccess 2018-04-1114:50 [IMPULSE-2018-00179] Preprint et al Tunable viscosity modification with diluted particles: When particles decrease the viscosity of complex fluids While spherical particles are the most studied viscosity modifiers, they are well known only to increase viscosities, in particular at low concentrations. Extended studies and theories on non-spherical particles find a more complicated behavior, but still a steady increase. [...] Restricted: PDF; 2018-04-1112:04 [IMPULSE-2018-00168] Preprint et al Liquid-liquid transition revealed by quasi-static cooling of an ultra-viscous metallic liquid Temperature-driven polyamorphism has been reported in various supercooled liquids and glasses. The dynamical and structural routes followed by the system during such crossovers are however not universal and appear to be related to intrinsic kinetic properties of the liquid. [...] Restricted: PDF; 2018-04-1110:57 [IMPULSE-2018-00163] Preprint et al Origin of Ferroelectricity in Orthorhombic $LuFeO_3$ In this Letter, we demonstrate that a small but finite ferroelectric polarization in orthorhombic LuFeO$_3$ is primarily of electronic origin (oriented along a-axis) driven by commensurate (k = 0) and collinear magnetic structure. The nonpolar orthorhombic lattice (space group $Pnma$) undergoes isostructural transition at the magnetic transition temperature $T_N$ ($\sim$600 K). [...] Restricted: PDF; 2018-04-1110:51 [IMPULSE-2018-00161] Preprint Hugenschmidt, C. In-situ observation of temperature-dependent segregation of Ni adatoms on oriented Pd surfaces We report the direct observation of the in-situ temperature-dependent surface segregation of Ni adatoms on single crystalline Pd surfaces using Positron annihilation induced Auger Electron Spectroscopy (PAES). For this study, a single atomic layer of Ni was grown on Pd with the crystallographic orientations Pd(111), Pd(110) and Pd(100). [...] Restricted: PDF; 2018-04-1014:32 [IMPULSE-2018-00141] Preprint Boeni, P. Neutron absorption in supermirror coatings: Effects on shielding The quantification of the dose rate and the composition of the dose in the vicinity of supermirror coated guides is essential for designing shielding for beamlines transporting neutrons with a high flux. We present results on a calculation of radiative neutron absorption in Ni/Ti and NiMo/Ti supermirror coatings which leads to the emission of high energy gamma rays. [...] Restricted: PDF; 2018-04-1010:45 [IMPULSE-2018-00137] Preprint et al Screened moments in a Kondo insulator Long known to have thermodynamic properties at odds with its insulating electrical transport, SmB6 has been the subject of great debate as it is unclear whether its unusual properties are related to the bulk or novel metallic surface states. We have observed a bulk moment-screening effect in nominally pure and Gd-doped SmB6 via heat capacity, magnetization, and resistivity measurements, and show this new Kondo-impurity like effect provides an unexpected but intuitive explanation for metal-like phenomena stemming from the strongly interacting host system. [...] 2017-12-2211:28 [FZJ-2017-08585] Preprint et al Spin dependence of {\eta} meson production in proton-proton collisions close to threshold Taking advantage of the high acceptance and axial symmetry of the WASA-at-COSY detector, and the high degree of the polarized proton beam of COSY, the reaction pp{\to} pp{\eta} has been measured close to threshold to explore the analyzing power Ay. The angular distribution of Ay is determined with the precision improved by more than one order of magnitude with respect to previous results allowing a first accurate comparison with theoretical predictions. [...] External links: OpenAccess; OpenAccess; OpenAccess; OpenAccess; OpenAccess; OpenAccess


text:
# Bernoulli's principle for a liquid with non uniform density

Consider a cylindrical container (section $$S$$, height $$H$$) which contains a liquid with non uniform density.

Let $$z$$ be the axis along the height of the container ($$z = 0$$ indicates the top of liquid while $$z = H$$ indicates the floor).

Suppose that the liquid stratifies in the container, i.e. the density is a function $$\rho(z) > 0$$, which is strictly increasing with $$z$$ ($$\rho'(z) > 0$$).

Suppose that atmospheric pressure is $$p_0$$. Then, according to the Stevin's law, the hydrostatic pressure is:

$$p'(z) = g\rho(z) \Rightarrow p(z) = p_0 + g\int_0^z \rho(s)ds.$$

Then, is it correct to write the Bernoulli's principle as follows

$$p(z) + \frac{1}{2}\rho(z)v^2(z) + \rho(z)g(H-z) = \text{constant} \Rightarrow\\ p_0 + g\int_0^z \rho(s)ds + \frac{1}{2}\rho(z)v^2(z) + \rho(z)g(H-z) = \text{constant}?$$

The liquid is steady, that is $$v(z) = 0 ~\forall z \in [0, H]$$. Then, the Bernoulli's principle reduces to:

$$p_0 + g\int_0^z \rho(s)ds + \rho(z)g(H-z) = \text{constant}.$$

Taking the derivative, I get:

$$g\rho(z) + \rho'(z)g(H-Z) - g\rho(z) = 0 \Rightarrow g(H-z)\rho'(z) = 0.$$

The last equation suggests me that

$$\rho'(z) = 0,$$

i.e. $$\rho(z) = \rho ~\forall z$$, which means that the fluid is uniform!!!

This results is really strange...

Does the Bernoulli's principle work for non uniform liquids? Is there any formulation of the Bernoulli's principle that takes into account a non uniform density?


text:
# What is the meaning of “algebraic construction”, and how could this be used in algebraic geometry

I try to make my question clear:

When reading a paper or listening a seminar talk, people showed me some set, and claim it to be a scheme; or some map, and claim it to be a morphism. I query why this is the case, and the answer sometimes goes as following : because every construction is algebraic, the result should be algebraic.

I don't know if this can be deemed as a proof or something easy to be checked (I am certainly a novice in AG) or a principle like Lefschetz principle. I do find a list of constructions called algebraic construction from Wikipedia. However I do not have any idea of how it is defined, and how to use them in the proof.

If you have heard similar explanation as I did, I hope you could understand my puzzle; and if you have use the similar explanation, I hope you could elaborate a little bit what does this exactly mean.

-
The people speaking to you are engaging in an abuse of notation/terminology that makes communication among experts efficient but can puzzle non-experts. One is using Yoneda's Lemma in certain technically powerful ways that experts express by describing a functor only on "complex points" rather than points valued in arbitrary (or finitely generated) $\mathbf{C}$-algebras -- the latter is what is actually needed in rigorous arguments but the notation can get clunky in that generality, so experts omit it; Mumford explains it extremely well in his book on abelian varieties. –  user36938 Jul 18 '13 at 14:35
@user36938 Thank you very much! Though I do not quite follow what your wrote, I feel your functor perspective is closed to how it is used. Could you elaborate on it? In particular, I did not see how was Yoneda lemma involved. There is one example in my mind: suppose for any $\mathbb{C}$-point $x$ in a variety $X$, one can associate a variety $V_x$, then why the set $\{(x,V_x)|x \in X\}$ is a variety. I think this construction is usually used in the context of semicontinuity theorem. Besides, if you could provide some example to illustrate your functor perspective, it will be very useful! –  Li Yutong Jul 19 '13 at 6:18
Certainly without more information about the nature of $V_x$ it is impossible to make sense out of the assertion that the collection of pairs $(x,V_x)$ (whatever on earth it could mean) "is a variety". It would be better for you to give an example that was told you. (What you said about $(x,V_x)$'s is too vague to be an example; more specificity about the $V_x$'s is needed.) –  user36938 Jul 19 '13 at 6:29
@user36938 It might be too complicate to explain the construction I mentioned. But general speaking, do you mean even if one views a construction is algebraic, to show it is really a variety or morphism, one still has to look into details and examine it. There is no fancy philosophy behind "algebraic construction". –  Li Yutong Jul 19 '13 at 11:35
Certainly there is some work to do, but it could be routine with experience. I don't know what you mean by "fancy philosophy", but there's nothing deep lurking in the shadows here, just a matter of familiarity or not with a certain technique. If you cannot provide any specific example then your request for clarification may be too vague to get a useful answer. –  user36938 Jul 19 '13 at 12:21

My naive point of view is: One avoids the use of ODEs or integrals (e.g., disguised as using the exponential mapping for Lie groups, ahem, algebraic groups) which quickly leads outside of the realm of polynomials and rational functions.

-

I think that there is no real perfect answer to your question.

Here is a simple example, that I often say in talks, I hope it can give an idea of what people mean when saying that a construction is algebraic.

Given any smooth cubic $C$ in the projective plane, and a point $p\in C$, I can define a birational map of the projective plane. A general line passing through $p$ is invariant and the restriction of the map to the line is the unique involution which fixes the two points of $C$ lying on the line which are distinct from the point $p$.

For the beginner, it is not clear that the map is really birational, but as soon as you deal with such constructions, you understand that if you give explicitly the point and the curve, then you can write the map with polynomials.

To see this, you can say that given a point in the plane, the equation of the line, of the points of intersections, and then of the image depend "algebraically" from the point. Hence the map is rational and does not involve for instance square roots or anything else.

-
As you know, square roots would be OK - we would just call it $y$'' and write $y^2 = f(x)$, etc. Exp and log would be another matter. :) –  user36938 Jul 19 '13 at 3:40
No, square roots are not allowed for a rational map. If you want a rational map from a variety $X$ to a variety $Y$, the image of a point $x\in X$ should depend algebraically from the coordinates in $X$ (i.e. be quotient of polynomials). –  Jérémy Blanc Jul 19 '13 at 19:25
@Jeremey: Sure, all I meant is that what looks like a "square root" from one point of view may be a "coordinate" from another; for the plane curve $C$ defined by $y^2 = f(x)$ one could say that the map $y:C \rightarrow \mathbf{A}^1$ is $P \mapsto \sqrt{f(x(P))}$. –  user36938 Jul 20 '13 at 0:05

I think I understand what you are asking. When one first learns about schemes, it is often very hard to link the language of schemes and the geometry. Suppose you are sitting in a seminar, and the speaker comments:

We are going to consider the Segre embedding $\mathbb{P}^1 \times \mathbb{P}^1 \to \mathbb{P}^3$ which is given by the formula $([x_0,x_1],[y_0,y_1]) \mapsto [x_0y_0,x_0y_1,x_1y_0,x_1y_1]$

this paints a very vivid picture. Indeed, if you are thinking about just sets and functions, everything is golden and this makes perfect sense. Even if you are thinking about manifolds, everything is fine. However, it is not immediately obvious how to translate such a statement into the language of schemes and that is one of the biggest hurdles when learning algebraic geometry, so lets walk through how the translation works in this case.

The formula above already gives a hint as to what is going on in the scheme world. Write $\mathbb{P}^3 = {\rm Proj} \mathbb{C}[z_{00},z_{01},z_{10},z_{11}]$. Being slightly imprecise (you can fix this by talking about line bundles) the homogeneous polynomial $z_{ij}$ pulls back to $x_i y_j$. This means that regular function $z_{pq} / z_{ij}$ pulls back to $x_p / x_i \cdot y_q / y_j$ which is a regular function on $D_+(x_i) \times D_+(y_j)$. We have described a morphism $D_+(x_i) \times D_+(y_j) \to D_+(z_{ij})$. Both of these schemes are affine so we only need to explain how regular functions pull back to describe the morphism. Now we want to glue all of these morphisms together. It is a little messy to write down but you can algebraically verify that both of the morphisms $D_+(x_i) \times D_+(y_j) \to D_+(z_{ij})$ and $D_+(x_i') \times D_+(y_j') \to D_+(z_{i'j'})$ restrict to the same morphism $$D(x_i' / x_i) \times D(y_j' / y_j) \to D(z_{i'j'} / z_{ij})$$ modulo changing coordinates (when you change coordinates on a product, you change coordinates on each component independently). This means they glue to give us an affine morphism $\mathbb{P}^1 \times \mathbb{P}^1 \to \mathbb{P}^3$ under which $z_{ij}$ pulls back to $x_i y_j$.

-
i just looked at your previously asked questions. Now I don't think this is what you were looking for... –  Daniel Barter Jul 18 '13 at 14:00
The "right" way is to use the functorial meaning of projective space as classifying line bundles equipped with an ordered tuple of generating global sections. Rather than busting out affine opens, make a functorial upgrading of the classical formula: for any scheme $S$ and line bundles $L,L'$ on $S$ equipped with generating global sections $(s_0,s_1)$ of $L$ and $(s'_0,s'_1)$ of $L'$, we get an ordered 4-tuple of global sections $(s_0\otimes s'_0,s_0\otimes s'_1,s_1\otimes s'_0, s_1\otimes s'_1)$ of $L\otimes L'$ that generate it. This works equally well as a definition for manifolds, etc! –  user36938 Jul 18 '13 at 14:40
@user36938: Thanks for the comment! I am still trying to absorb the sheafy terminology –  Daniel Barter Jul 18 '13 at 15:26
Daniel, as an exercise, you should check that the $i$th "standard affine open" in $\mathbf{P}^n$ has the functorial characterization as classifying those pairs $(L, (s_0,\dots,s_n))$ such that $s_i$ generates $L$ globally (i.e., $s_i$ is "everywhere non-vanishing"). –  user36938 Jul 19 '13 at 3:30

Sorry, if my answer is to ambiguous.

An object $X$ e.g a curve, a morphism, is a subset of a bigger set e.g $\mathbb{C}^n$ or the set of pairs $(x,y)$. To describe $X$ is to give some restrictions that defined it. Whenever someone says "the contruction is algebraic" I imagine those restrictions are "locally" given by algebraic relations e.g polynomials. Similarly, whenever someone says "an object or relation is algebraic". I imagine that it can be constructed by "a finite combination of steps or operations"

-


text:
bug-gnu-emacs
[Top][All Lists]

## bug#11585: 24.0.50; corrupted byte compiled files

 From: Pierre Lorenzon Subject: bug#11585: 24.0.50; corrupted byte compiled files Date: Wed, 30 May 2012 08:57:06 +0200 (CEST)

This bug report will be sent to the Free Software Foundation,
not to your local site managers!
Please write in English if possible, because the Emacs maintainers
usually do not have translators to read other languages for them.

and to the gnu.emacs.bug news group.

Please describe exactly what actions triggered the bug
and the precise symptoms of the bug.  If you can, give
a recipe starting from emacs -Q':

Hi,

Certain of my .el files are incorrectly compiled. See the .elc
file with a long name.

More details : It seems that a part of the .elc file is missing
as if a part of the character strream was discarded. I cannot
figure out why.

But more suprisingly when renaming the file with a much more
shorter name everything goes well as if there was a limitation
in the file name length. I must point out that there are only
ascii characters composing the file name.

Moreover even with the long name the .el (uncompiled file) is
perfectly correct and load perfectly as well as the .elc
(compiled file) with the short name.

I had this problem with emacs 24.0.50 as well as witth
24.0.95. I should say that I am using these devloppeing
versions since I appreciate ieieio to be integrated in it. I
never had this compilation problem with emacs 23 but probalbly
never tried with so long file names. Moreover emacs 23 is no
longer available on my system to test. But if it could be
useful I can reinstall this stable version.

See examples attached.

Is there a limitation somewhere ?

Regards

Pierre

If Emacs crashed, and you have the Emacs process in the gdb debugger,
please include the output from the following gdb commands:
bt full' and xbacktrace'.
/usr/share/emacs/24.0.50/etc/DEBUG.

In GNU Emacs 24.0.50.1 (i686-pc-linux-gnu)
of 2011-01-13 on jabberwocky
configured using configure  '--prefix=/usr' '--libexecdir=/usr/lib'
'--localstatedir=/var''

Important settings:
value of $LC_ALL: nil value of$LC_COLLATE: nil
value of $LC_CTYPE: nil value of$LC_MESSAGES: nil
value of $LC_MONETARY: nil value of$LC_NUMERIC: nil
value of $LC_TIME: nil value of$LANG: C
value of $XMODIFIERS: nil locale-coding-system: nil default enable-multibyte-characters: t Major mode: Message Minor modes in effect: gpm-mouse-mode: t tool-bar-mode: t desktop-save-mode: t global-ede-mode: t global-speechd-speak-mode: t speechd-speak-mode: t global-speechd-speak-map-mode: t speechd-speak-map-mode: t menu-bar-mode: t file-name-shadow-mode: t global-font-lock-mode: t auto-composition-mode: t auto-encryption-mode: t auto-compression-mode: t line-number-mode: t transient-mark-mode: t Recent input: d i s c o v e r SPC w h e r e SPC i s SPC t h SPC p r o b l e m SPC . . . . ESC q RET RET RET TAB T h a n k s SPC RET RET TAB P I e r r e ESC [ 1 ~ ESC [ C ESC [ C ESC [ C ESC [ 3 ~ i ESC [ 4 ~ C-c C-c y ESC [ A . C-x o ESC [ B C-@ ESC [ B ESC [ B ESC [ B ESC [ B ESC [ B ESC [ B ESC [ B ESC [ B ESC [ B ESC [ B ESC [ B ESC [ B ESC [ B ESC [ B ESC [ B ESC [ B ESC [ B ESC [ B ESC [ B ESC [ B ESC [ B ESC [ B ESC [ B ESC [ B ESC [ B ESC [ B ESC [ B ESC [ B ESC [ B ESC [ B ESC [ B ESC [ B ESC [ B ESC [ B ESC w C-x o ESC [ A ESC [ A C-x o ESC [ A ESC [ B ESC [ B ESC [ B ESC [ B ESC [ B . C-x o ESC [ B ESC [ B ESC [ B ESC [ B ESC [ B ESC [ B ESC [ B ESC [ B ESC [ B ESC [ B ESC [ B ESC [ B ESC [ B ESC [ B ESC [ B ESC [ A ESC [ A ESC [ A ESC [ A ESC [ A ESC [ B ESC x r e p o TAB r TAB b TAB RET Recent messages: +draft/4 has been queued to +queue/3 (from Draft mode) Connecting to the SMTP server...done Sending in background...done Mark set line-move-visual: End of buffer Saved text from "Hi, Certain of my .el files are incorre" line-move-visual: Beginning of buffer Making completion list... Load-path shadows: /usr/local/share/emacs/site-lisp/customization/site-start hides /usr/share/emacs/site-lisp/site-start /usr/share/emacs/site-lisp/speechd/speechd hides /usr/share/emacs/site-lisp/speechd.cvs/speechd /usr/share/emacs/site-lisp/speechd/speechd-ssip hides /usr/share/emacs/site-lisp/speechd.cvs/speechd-ssip /usr/share/emacs/site-lisp/speechd/speechd-speak hides /usr/share/emacs/site-lisp/speechd.cvs/speechd-speak /usr/share/emacs/site-lisp/speechd/brltty hides /usr/share/emacs/site-lisp/speechd.cvs/brltty /usr/share/emacs/site-lisp/speechd/mmanager hides /usr/share/emacs/site-lisp/speechd.cvs/mmanager /usr/share/emacs/site-lisp/speechd/speechd-common hides /usr/share/emacs/site-lisp/speechd.cvs/speechd-common /usr/share/emacs/site-lisp/speechd/speechd-version hides /usr/share/emacs/site-lisp/speechd.cvs/speechd-version /usr/share/emacs/site-lisp/speechd/speechd-out hides /usr/share/emacs/site-lisp/speechd.cvs/speechd-out /usr/share/emacs/site-lisp/speechd/braille hides /usr/share/emacs/site-lisp/speechd.cvs/braille /usr/share/emacs/site-lisp/speechd/speechd-bug hides /usr/share/emacs/site-lisp/speechd.cvs/speechd-bug /usr/share/emacs/site-lisp/speechd/speechd-braille hides /usr/share/emacs/site-lisp/speechd.cvs/speechd-braille /usr/share/emacs/site-lisp/speechd/speechd-brltty hides /usr/share/emacs/site-lisp/speechd.cvs/speechd-brltty /usr/share/emacs/site-lisp/speechd/speechd-compile hides /usr/share/emacs/site-lisp/speechd.cvs/speechd-compile Features: (shadow emacsbug help-mode view pp mew-varsx vc-cvs vc-rcs j++-packages-cdrom-projects-category j++-packages-cdrom-projects-categories j++-packages-cdrom-projects-references j++-packages-cdrom-projects-pieces j++-packages-cdrom-projects-performer j++-packages-cdrom-components-performer j++-packages-databases-cds-performer j++-packages-cdrom-projects-performers j++-packages-cdrom-projects-discid j++-packages-cdrom-projects-discids j++-packages-cdrom-projects-piece j++-packages-cdrom-projects-type j++-packages-cdrom-projects-author j++-packages-cdrom-projects-authors j++-packages-cdrom-projects-all j++-packages-cdrom-projects-project j++-sound-project j++-packages-sound-sound-project j++-packages-cdrom-components-reference j++-packages-cdrom-components-discid j++-packages-cdrom-components-author j++-packages-cdrom-components-person j++-packages-databases-cds-author j++-packages-databases-items-person j++-packages-cdrom-components-piece j++-packages-cdrom-components-item j++-packages-cdrom-track j++-basic-processes-asynchronous j++-basic-flaggable j++-packages-project-target j++-basic-widgets-open-close-title j++-basic-widgets-open-close j++-packages-cdrom-cddb-client j++-basic-processes-network-stream j++-packages-cdrom-cdda-client j++-basic-processes-queueable j++-basic-parsers-parser j++-basic-mastered j++-packages-cdrom-cdrom j++-basic-string-filter j++-basic-duration j++-basic-interfaces-pointed j++-basic-interfaces-interface j++-basic-lists-pointed j++-basic-creator j++-basic-lists-list j++-basic-mapable j++-basic-sortable j++-basic-state j++-basic-widgets-synchronized j++-basic-synchronized j++-basic-widgets-object t-mouse info tool-bar reftex-auc reftex-vcr reftex-dcr reftex reftex-vars noutline outline font-latex newcomment Tss-LaTeX-remap latex easy-mmode edmacro kmacro tex-style tex j++-project j++-packages-project-project j++-packages-project-file j++-basic-processes-svn j++-basic-processes-synchronous j++-basic-processes-process j++-basic-files-file-manager j++-basic-files-file j++-basic-files-serializable j++-basic-files-stringifiable ede/dired ede/proj-elisp ede/pconf package desktop speechd-el-extension Tss-TeX-remap tex-style-system tex-style-system-eieio Tss-context Tss-common Tss-widget Tss-util tree pln-auctex tex-site auto-loads pln-ede latex/edext-target-exercise latex/edext-latex edext-project edext-vc vc-svn vc vc-dispatcher edext-srecode semantic/edit semantic/find srecode/srt-mode semantic/analyze semantic/sort semantic/scope semantic/analyze/fcn semantic/db semantic/format srecode/template srecode/srt-wy semantic/wisent semantic/wisent/wisent semantic/ctxt srecode/ctxt semantic/tag-ls srecode/compile srecode/table srecode/map semantic/util-modes semantic/util semantic semantic/tag semantic/lex semantic/fw edext-utils edext ede/proj-misc ede/pmake ede/proj-obj ede/proj ede/make ede/proj-comp ede/autoconf-edit autoconf autoconf-mode j++ ede/linux ede/emacs ede/cpp-root srecode mode-local ede/speedbar ede/files speechd-el-ede ede ede/source eieio-base eieio-speedbar speedbar sb-image ezimage dframe assoc eieio-custom cedet pln-mew mew-w3m speechd-el-w3m w3m browse-url doc-view jka-compr dired regexp-opt image-mode timezone w3m-hist w3m-fb w3m-ems wid-edit warnings w3m-ccl ccl w3m-favicon image w3m-image w3m-proc w3m-util mew-auth mew-config mew-imap2 mew-imap mew-nntp2 mew-nntp mew-pop mew-smtp mew-ssl mew-ssh mew-net mew-highlight mew-sort mew-fib mew-ext mew-refile mew-demo mew-attach mew-draft mew-message mew-thread mew-virtual mew-summary4 mew-summary3 mew-summary2 mew-summary mew-search mew-pick mew-passwd mew-scan mew-syntax mew-bq mew-smime mew-pgp mew-header mew-exec mew-mark mew-mime mew-edit mew-decode mew-encode mew-cache mew-minibuf mew-complete mew-addrbook mew-local mew-unix mew-vars3 mew-vars2 mew-vars mew-env mew-mule3 mew-mule mew-gemacs easymenu mew-key mew-func mew-blvs mew-const speechd-el-mew mew pln-w3m pln-customization speechd-speak advice help-fns advice-preload speechd-ssip speechd-brltty speechd-braille braille mmanager brltty cl cl-19 speechd-out eieio byte-opt bytecomp byte-compile speechd speechd-common ediff-hook vc-hooks lisp-float-type lisp-mode register page menu-bar rfn-eshadow timer jit-lock font-lock syntax facemenu font-core frame cham georgian utf-8-lang misc-lang vietnamese tibetan thai tai-viet lao korean japanese hebrew greek romanian slovak czech european ethiopic indian cyrillic chinese case-table epa-hook jka-cmpr-hook help simple abbrev loaddefs button minibuffer faces cus-face files text-properties overlay md5 base64 format env code-pages mule custom widget hashtable-print-readable backquote make-network-process multi-tty emacs)  Toto.elc Description: Binary data (TeX-add-style-hook '(Tss-slave :name "Etude-des-Fonctions-Zeta-des-Courbes-Modulaires-Aux-Places-de-Bonne-Reductions/Reformulation-En-Theorie-des-Groupes" :master-directory "../" :state (new)) (lambda () (TeX-style-system-init-master "../Scholze") (LaTeX-add-index-entries "$\\sigma$-conjugués" "$\\sigma$-centralisateur" ) (LaTeX-add-labels "SCH.zeta.groupe" "SCH.zeta.groupe.lem.8" "SCH.zeta.groupe.pro.4" "SCH.zeta.groupe.lem.10" "SCH.zeta.groupe.thm.7" "SCH.zeta.groupe.pro.5" ) ) )  Reformulation-En-Theorie-des-Groupes.elc Description: Binary data (TeX-add-style-hook '(Tss-slave :name "Etude-des-Fonctions-Zeta-des-Courbes-Modulaires-Aux-Places-de-Bonne-Reductions/Reformulation-En-Theorie-des-Groupes" :master-directory "../" :state (new)) (lambda () (TeX-style-system-init-master "../Scholze") (LaTeX-add-index-entries "$\\sigma$-conjugués" "$\\sigma\$-centralisateur"
)
"SCH.zeta.groupe"
"SCH.zeta.groupe.lem.8"
"SCH.zeta.groupe.pro.4"
"SCH.zeta.groupe.lem.10"
"SCH.zeta.groupe.thm.7"
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)

)
)


text: Terahertz cyclotron emission from two-dimensional Dirac fermions Auteur(s): Gebert S., Consejo C., Krishtopenko S., Ruffenach S., Szola M., Torres J., Bray C., Jouault B., Orlita M., Baudry X., Ballet P., Morozov S., Gavrilenko V., Mikhailov N., Dvoretskii S., Teppe F. (Article) Publié: Nature Photonics, vol. p. (2023) Ref HAL: hal-03940773_v1 DOI: 10.1038/s41566-022-01129-1 Exporter : BibTex | endNote Résumé: Since the emergence of graphene, we have seen several proposals for the realization of Landau lasers tunable over the terahertz frequency range. The hope was that the non-equidistance of the Landau levels from Dirac fermions would suppress the harmful non-radiative Auger recombination. Unfortunately, even with this non-equidistance, an unfavourable non-radiative process persists in Landau-quantized graphene, and so far no cyclotron emission from Dirac fermions has been reported. One way to eliminate this last non-radiative process is to sufficiently modify the dispersion of the Landau levels by opening a small gap in the linear band structure. HgTe quantum wells close to the topological phase transition are a proven example of such gapped graphene-like materials. In this work we experimentally demonstrate Landau emission from Dirac fermions in such HgTe quantum wells, where the emission is tunable by both the magnetic field and the carrier concentration. Consequently, these results represent an advance in the realization of terahertz Landau lasers tunable by a magnetic field and gate voltage.


text:
# Correcting an error vs reviewing code

So there has been a lot of discussion about what purpose a code review will have in this site. Whether or not users should be able to bring a "Help me my code is broken" to this site.

So, what does a code review mean to you? what are the pre-conditions for a code review (input) and what kind of outcomes (output) can a user expect?

(this should be a community wiki, I know, but no option at the moment)

• Fixing broken code is for Stack Overflow; optimizing and offering feedback on working code would be more suited for Code Review. That's how I see it, at least. – Andrew Jan 20 '11 at 5:52

Not sure these are the way, just a way that looks good right now. So it's a list of desired features.

Input:

• Programmer believes that high level code/algorithm works correctly.

• If in a sane language, has passed done lint/check-list cleanup on code.

• Should excerpt if and as much as possible, while offering enough code to make it understandable.

• Is free to contain FIXME, TODO or XXX, as long as OP don't expect peers to fix those bits for them.

• Context on goals, alternatives, etc. is welcome.

Output:

• Respects design decisions, may politely suggest/cite alternatives.

• As pedantic as possible in any dimension the OP asks for it, politely pedantic on others (preferably not on personal style choices).

• Clear, concise suggestions, optionally backed by extended arguments and examples.

• General comments about problematic sections or anti-patterns are OK, if constructive and polite.

• +1 for "as long as OP don't expect peers to fix those bits for them." – cbrulak Jan 20 '11 at 2:16

What i'd like to see is: "Help me my design is broken"

What i woudn't like to see: "There is a parser error that i can't figure out". I think those question are better suited for SO as they don't really require an in depth code review and most people that ask those question just want their problem fixed and not talk about complexity or readabilty.

I think TryPyPy provided a very solid list (+1)

• This is an acceptable attitude. Compiler errors (or similar) should be resolved before the code gets here, but help on program structure doesn't seem like it should be out of bounds. – Inaimathi Jan 20 '11 at 15:03

At my company (where I work, not my own company) we focus code reviews on detecting defects as a number 1 priority (but we also assume code in review will compile and pass tests).

We also ensure that code meets coding guidelines (spaces vs tabs, placement of curly braces,etc).

And, most importantly, that any long term maintenance issues are covered.


text:
IMPORTANT NOTE

is still available in RDS.

## What does it change and why is so important?

Tracking databases and not just tables counters in Postgres isn’t cheap, but since some time ago there were workarounds involving the setup of a ramdisk to place the directory pointed by stat_temp_directory GUC variable. That directory places a global.stat and a per-database stat files called like db_<oidOfDB>.stat. Although the mechanism for writing into these files avoids extra or unnecessary flushes, it is very write intensive.

This change does not require any downtime (in standalone installations), as a simple reload will force the Stat Collector to rewrite the files on the folder. There is a pretty much clear blog on putting stat_temp_directory on a ramdisk.

The problem relies on the RDS lack of privileges to manipulate file or directory contents, which does not allow you to check the current size and set a proper value. Although, you may probably want to know that there is a limit of 1 GB for this setting in RDS.

If you don’t want any further details and you want to relief your storage, set it to 256 MB and continue with your life. Even though is a large setting (next paragraph explain why), you don’t want to fall short on it.

After you apply the change over pg_stat_ramdisk_size, you will see the location in the RDS have changed:

show stats_temp_directory;
stats_temp_directory
---------------------------
/rdsdbramdisk/pg_stat_tmp

## TL;DR What’s the expected size of the stat_temp_directory?

Before move forward, lets detail the structure of the entries for the stat file:

Structure/Constant Size
PGSTAT_FILE_FORMAT_ID 1 byte
PgStat_StatTabEntry 164 bytes
PgStat_StatFuncEntry 28 bytes
closingChar ‘E’
describers char (T or F in this case)

First of all, as it’ll explained later, not all the tables, indexes and functions are written on the db statsfile. Basically, a basic formula will be:

_SizeOfDBStatFile = PGSTAT_FILE_FORMAT_ID + describers + (tableCount * PgStat_StatTabEntry) + (funcCount * PgStatStatFuncEntry) + closingChar

In order to get the estimate space needed for the current tables on each database (keep in mind that this considers all tables flushed on file), there is a query you can execute safely on each database in your PostgreSQL instance (statfile is one per database):

SELECT count(*) * 164 "size in bytes"
FROM pg_class
WHERE relkind ('r','i','S');

Also, you need to do the same within pg_proc, but instead the factor will be 28 bytes. You’ll need to run this on every database, and sum them all. This is for tracking stats for function usage, which can be disabled from the postgresql.conf file with the track_functions variable. Also, all the aspects of runtime statistics can be found here.

### Global Stats

Structure of the global stats:

Structure Size
PgStat_StatDBEntry 180 bytes
PgStat_GlobalStats 92 bytes
PgStat_ArchiverStats 114 bytes
describer char (’D’)

The global statfile is smaller, and contains only the global stats and the counters across databases. Should be something close to:

_PGSTAT_FILE_FORMAT_ID + describer + PgStat_GlobalStats + PgStat_ArchiverStats + (PgStatStatDBEntry + describer) * numDatabases.

So, as you can see, the limitation imposed by AWS in regarding is way above the amount of data held on this directory in most of the databases that can run inside RDS expectations.

## Why it affects RDS?

Prior to this feature been added, the stat_temp_directory had a place into the persistent storage layer. This was the same as any other Postgres installation by default, however due to the storage characteristics of RDS the impact could be considered higher than a standalone setup.

If your application is write intensive, you will see the impact on the Write latency and operations.

## A deeper look

So the question didn’t took much time to appear in the network and, I wasn’t the exception. Is there a way to pre calculate the contents of the directory?

I couldn’t end up with an exact number however, you may know that the size of the files are more related to the number of tables, indexes, functions and databases. The following structure is the core of this implementation. It is so important that it actually has a defined PGSTAT_FILE_FORMAT_ID that it is written also in the stat files.

All the structures for these file contents are placed in the include/pgstat.h header and its implementation is done in postmaster/pgstat.c (as it is a startup worker). Every field that is used for counters use int64 and there are some timestampz (64 bits too) with Oid as an exception, which is represented by 32 bits (unsigned int).

Backends communicate to the collector through StatMsgType struct, when is different from a zeroed struct PgStat_TableCounts. Structures kept in backend local memory while accumulating counts. So, that means that not all the tables, indexes and functions will have an entry.

Which backends can request a file write? All the backends, the archiver, the bgwriter. All of them use the same structure for passing the changes (PgStat_Msg).

There are 2 functions for write (pgstat_write_db_statsfile, pgstat_write_statsfiles) and 2 for read (pgstat_read_db_statsfile ,pgstat_read_statsfiles ) each of those controlling either the db_<oid>.stat and global.stat.

## References

### PgStat_StatDBEntry

The HTAB structure is opaque, and it holds a hash map of tables and functions to be collected. We don’t care about the size of this maps as it won’t be written to the stats file anyway. The whole database entry is 22 * 64 bit values + 1 * 32 bits, per database (180 bytes).

#define PGSTAT_FILE_FORMAT_ID   0x01A5BC9D
typedef struct PgStat_StatDBEntry
{
/*
NOTE:
The oid type is currently implemented as an unsigned four-byte integer.
typedef unsigned int Oid;
*/
Oid                     databaseid;
PgStat_Counter n_xact_commit;
PgStat_Counter n_xact_rollback;
PgStat_Counter n_blocks_fetched;
PgStat_Counter n_blocks_hit;
PgStat_Counter n_tuples_returned;
PgStat_Counter n_tuples_fetched;
PgStat_Counter n_tuples_inserted;
PgStat_Counter n_tuples_updated;
PgStat_Counter n_tuples_deleted;
TimestampTz last_autovac_time;
PgStat_Counter n_conflict_tablespace;
PgStat_Counter n_conflict_lock;
PgStat_Counter n_conflict_snapshot;
PgStat_Counter n_conflict_bufferpin;
PgStat_Counter n_temp_files;
PgStat_Counter n_temp_bytes;
PgStat_Counter n_block_read_time;       /* times in microseconds */
PgStat_Counter n_block_write_time;

TimestampTz stat_reset_timestamp;
TimestampTz stats_timestamp;    /* time of db stats file update */

/*
* tables and functions must be last in the struct, because we don't write
* the pointers out to the stats file.
*/
HTAB       *tables;             // defined in utils/hsearch.h
HTAB       *functions;
} PgStat_StatDBEntry;

### Structures

In overal, this is the structure size of each:

Structure Detail Total
PgStat_StatTabEntry 20 * 64 bits and 1 * 32 Oid (164 bytes)
PgStat_StatFuncEntry 3 * 64 bits and 1 * 32 Oid (28 bytes)
PgStat_GlobalStats 11 * 64 bits, 8 bytes + 1 * 32 bit, 4 bytes (92 bytes)
PgStat_ArchiverStats 4 * 8bytes, 2 char 41 bytes. (114 bytes)

Hope you enjoyed the article!


text:
# From the top of a 7m high building, the angle of elevation of the top of a cable tower is 60° and the angle of depression of its foot is 45°.

166k views

From the top of a 7m high building, the angle of elevation of the top of a cable tower is 60° and the angle of depression of its foot is 45°. Determine the height of the tower.

by (128k points)
selected

Let AB be the building of height 7 m and EC be the height of tower.
A is the point from where elevation of tower is 60° and the angle of depression of its foot is 45°
EC = DE + CD
also, CD = AB = 7 m.
A/q,
In  right ΔABC,
tan 45° = AB/BC
⇒ 1= 7/BC
⇒ BC = 7 m = AD
also,
⇒ √3 = DE/7
⇒ DE = 7√3 m
Height of the tower = EC =  DE + CD
= (7√3 + 7) m = 7(√3+1) m.


text:
## Tit for Tat (the shutdown thread)

Lies, damned lies, and statistics.
Skeeve
Posts: 10748
Joined: Wed Jun 09, 2004 7:35 am

### Re: Tit for Tat (the shutdown thread)

76% HAVE HARDLY NOTICED SHUTDOWN
Note, this was published on Jan. 3rd, 2019. I wonder what the polls will be next time.
Seventy-six percent (76%) of voters have hardly noticed the partial shutdown of the federal government. That total includes 42% who have felt no impact, 19% who have felt hardly any impact, and 15% who aren’t aware there’s a shutdown.

A new ScottRasmussen.com survey found that 15% have felt a minor impact and 9% claim to have felt a major impact from the shutdown.

The survey of 1,000 Registered Voters was conducted January 2 and 3, 2018.

While the 9% feeling a major impact is a relatively modest number, it represents an increase from last week when only 6% claimed to have felt a major impact from the shutdown.
As this shit show goes on, more and more folks may begin to wonder:
Do we really need all these bureaucrats?
Then Skank Of America could start in...

Skeeve
Posts: 10748
Joined: Wed Jun 09, 2004 7:35 am

### Re: Tit for Tat (the shutdown thread)

Seek and ye shall find, Update:15% NOW FEELING MAJOR IMPACT FROM SHUTDOWN

Posted on January 15, 2019 | by Scott Rasmussen
Fifteen percent (15%) of voters nationwide now say the have personally felt a major impact from the partial government shutdown. That’s up from 12% a week ago, 9% the week before, and 6% in late December.

A ScottRasmussen.com survey found that 21% of Democrats claim a major impact from the shutdown along with 13% of Independent voters and 10% of Republicans (see crosstab results)

Overall, 18% have felt a minor impact and 67% hardly any or no impact.

Fifty-one percent (51%) of voters believe the shutdown will last a few more weeks. Thirty-four percent (34%) believe it will last longer while 15% expect it to be resolved in a matter of days.
Personally, I dont see any difference. Has anyone else here at SC noticed it yet?
...
Fifty percent (50%) of voters believe furloughed government workers should be encouraged to seek jobs in the private sector. Twenty-four percent (24%) disagree and 26% are not sure.

Data released earlier showed that 78% favor changing the law so that employees who are required to work during the shutdown can get paid on time.

When the shutdown is over, 46% favor a plan to reduce the number of federal employees while 35% are opposed.
Then Skank Of America could start in...

ed
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### Re: Tit for Tat (the shutdown thread)

SIL works for the county and some of his salary is paid for by the feds, that part is missing. Didn't realize that the federal claws were set that deep.
Wenn ich Kultur höre, entsichere ich meinen Browning!

Skeeve
Posts: 10748
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### Re: Tit for Tat (the shutdown thread)

In Trump country, Republicans cheer on shutdown: The 'government is our biggest enemy'
CRAIG, Colo. – Ten words in faded red ink adorn the glass door of the federal building: "Please hold mail for duration of government shutdown. Thank you."

Here in this northern Colorado coal town, those 10 words, and the unplowed parking lot of that Bureau of Land Management facility, are among the few obvious signs that the nation's federal government is partially closed, resulting in nearly 1 million American workers not getting their taxpayer-paid paychecks.

Many of Craig's 9,000 residents are just fine with that.
...
"It kind of makes me question what they do on a day-to-day basis," says Paul James, 31, who runs the town's sole medical marijuana dispensary. "If I don't miss them, what were they doing?"

Sure, some folks are worried that their relatives in the military aren't getting paid right now. Others are worried about access to federal loan guarantees or getting their tax refunds on time. More than a handful believe the shutdown makes the country look foolish. But generally, Craig's residents are unfazed by the shutdown that's approaching one month and showing no signs of ending. They point out that federal employees eventually will get their salaries even though some didn't even work and that many of those nonessential workers are getting a lengthy vacation.
The word from one 'fly-over' state
Then Skank Of America could start in...

Grammatron
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Location: Los Angeles, CA

### Re: Tit for Tat (the shutdown thread)

https://www.duffelblog.com/2019/01/troo ... cancelled/
BAGRAM AIR BASE, Afghanistan — Service members currently deployed to Afghanistan were devastated when they learned that Speaker of the House Nancy Pelosi and her entourage of congressmen had cancelled their planned visit this past weekend, sources confirmed today.

President Donald Trump halted the congressional delegation’s trip seemingly in response to Pelosi suggesting the president cancel or delay his State of the Union address, citing security concerns. The bus filled with congressman was stopped at the way to Joint Base Andrews where military aircraft were prepared to carry the representatives to Afghanistan.

“It’s terrible,” Staff Sgt. Paul Morin said. “They were going to cancel the vehicle inspection so we could all go shake her hand for six seconds, but then we had to clean all the vehicles three times.”

“It’s a shame,” Sgt. 1st Class Mark Klages said. “Morale has gotten get pretty low around here with the holidays being over, the awful weather, the ANA’s incompetence and our confusing strategy, but it would have helped a lot to be talked at by an old lady from San Francisco.”

Some service members seemed confused as to who the current House speaker actually is.

“Pelosi? Of course I’m upset she didn’t come,” Sgt. Frank Lauer said. “She’s the hot Puerto-Rican one right?”

Anaxagoras
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Location: Yokohama/Tokyo, Japan

Latest headlines I'm seeing are that democrats are offering $5.7 billion for border security, just not for the wall. So it isn't about money. A fool thinks himself to be wise, but a wise man knows himself to be a fool. William Shakespeare Abdul Alhazred Posts: 72894 Joined: Mon Jun 07, 2004 1:33 pm Title: Yes, that one. Location: Chicago ### Re: Tit for Tat (the shutdown thread) Anaxagoras wrote: Wed Jan 23, 2019 11:12 pm Latest headlines I'm seeing are that democrats are offering$5.7 billion for border security, just not for the wall. So it isn't about money.
It's about Trump having to surrender.

Not quite symmetrical because from Trump's POV it's about blaming the Democrats for the shutdown,
which would be an actual reversal of a Democrat win already accomplished.
Any man writes a mission statement spends a night in the box.
-- our mission statement plappendale

Witness
Posts: 18254
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### Re: Tit for Tat (the shutdown thread)

From January 4th:
Trump threatened to keep the government closed for 'months or even years' in meeting with top Democrats
https://www.cnbc.com/2019/01/04/trump-t ... -says.html

sparks
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### Re: Tit for Tat (the shutdown thread)

Wouldn't it be just fucking precious if we elected a Dem in 2020 because he/she promised to 'reopen' the goobermint?
You can lead them to knowledge, but you can't make them think.

corplinx
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### Re: Tit for Tat (the shutdown thread)

There's a shutdown going on? Eh, go figure.

Abdul Alhazred
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### Re: Tit for Tat (the shutdown thread)

Bear in mind that in addition to "non-essential" and "essential", there are also agencies already fully funded by separate legislation.
Any man writes a mission statement spends a night in the box.
-- our mission statement plappendale

Giz
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Location: UK

### Re: Tit for Tat (the shutdown thread)

Anaxagoras wrote:
Wed Jan 23, 2019 11:12 pm
Latest headlines I'm seeing are that democrats are offering $5.7 billion for border security, just not for the wall. So it isn't about money. On what grounds is a 5 billion wall more egregious than 5 billion of border patrol officers asking to see “ papers please”? It seems like conceding the material argument and just arguing over theatrics. Abdul Alhazred Posts: 72894 Joined: Mon Jun 07, 2004 1:33 pm Title: Yes, that one. Location: Chicago ### Re: Tit for Tat (the shutdown thread) Giz wrote: Thu Jan 24, 2019 12:52 am ... arguing over theatrics. Someone gets it. Any man writes a mission statement spends a night in the box. -- our mission statement plappendale Anaxagoras Posts: 22900 Joined: Wed Mar 19, 2008 5:45 am Location: Yokohama/Tokyo, Japan ### Re: Tit for Tat (the shutdown thread) Giz wrote: Thu Jan 24, 2019 12:52 am Anaxagoras wrote: Wed Jan 23, 2019 11:12 pm Latest headlines I'm seeing are that democrats are offering$5.7 billion for border security, just not for the wall. So it isn't about money.
On what grounds is a 5 billion wall more egregious than 5 billion of border patrol officers asking to see “ papers please”? It seems like conceding the material argument and just arguing over theatrics.
I can't disagree with that. It's about who gets to declare victory when this is all over.

Also, as I understand it, there's already about 700 miles of wall or fence on the U.S.-Mexican border.

But this was Trump's "signature" political promise to voters. So . . .
A fool thinks himself to be wise, but a wise man knows himself to be a fool.
William Shakespeare

Nyarlathotep
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### Re: Tit for Tat (the shutdown thread)

Trump and the Republicans in Congress have their base that they have to mollify. The Dems in Congress have THEIR base that they have to mollify. Nothing else matters to them. THus neither has any interest in ending the shutdown in any manner that does not involve complete capitulation from the other.
Bango Skank Awaits The Crimson King!

Abdul Alhazred
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### Re: Tit for Tat (the shutdown thread)

Nyarlathotep wrote:
Thu Jan 24, 2019 1:35 am
Trump and the Republicans in Congress have their base that they have to mollify. The Dems in Congress have THEIR base that they have to mollify. Nothing else matters to them. THus neither has any interest in ending the shutdown in any manner that does not involve complete capitulation from the other.
Modulo Trump and the Republicans in congress are pulling in slightly different directions.
Any man writes a mission statement spends a night in the box.
-- our mission statement plappendale

Giz
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Location: UK

### Re: Tit for Tat (the shutdown thread)

Assuming that the dems have more furloughed voters than the reps, I wonder if they expect that continuing the pain helps rally (rile up) their base. Maybe they don't want the shutdown to end. Until 2020.

Anaxagoras
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### Re: Tit for Tat (the shutdown thread)

I don't believe either of them really want that. But, they want to find a way out without capitulating, or appearing to capitulate.

I would suggest looking for a compromise, but I'm probably pretty far on the moderate wing of the Democratic party at this point. The left wing of the party doesn't want any compromise.
A fool thinks himself to be wise, but a wise man knows himself to be a fool.
William Shakespeare

Nyarlathotep
Posts: 48097
Joined: Fri Jun 04, 2004 2:50 pm

### Re: Tit for Tat (the shutdown thread)

No, they want a way out that makes the OTHER side capitulate. Compromise is not in the cards. It's not even a desired goal. They may or may not actually want people to suffer financially but at best they give zero fucks that it is happening.
Last edited by Nyarlathotep on Thu Jan 24, 2019 2:21 am, edited 1 time in total.
Bango Skank Awaits The Crimson King!

Skeeve
Posts: 10748
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### Re: Tit for Tat (the shutdown thread)

House rejects GOP measure to pay workers but not open government
The House rejected a GOP measure to pay furloughed workers but keep the government closed in a 222-195 vote.

Six Democrats voted for the GOP measure, offered as an alternative to a Democratic bill to reopen the government.
So much for democrats worrying about the poor starving federal workers...

Also, a video: Democrats to Pelosi: "Give Trump the Money"

Then Skank Of America could start in...


text:
# Example of a commutative, local, dual ring with nilradical $N$ such that $ann(N)\nsubseteq N$

For an ideal $I\lhd R$ in a commutative ring $R$, let $ann(I)$ denote the annihilator of $\{x\in R\mid xI=\{0\}\}$. A commutative ring $R$ is said to be a dual ring if for every ideal $I$ of $R$, $ann(ann(I))=I$.

What are examples of commutative, local, dual rings with nonzero Krull dimension whose nilradical $N$ satisfies $ann(N)\nsubseteq N$? (Or is this not possible?!)

I'd be surprised if examples weren't possible.

A great deal of commutative, local, dual rings that I've encountered (many of them trace back to Hajarnavis and Norton's articles) turn out to be zero dimensional, so their Jacobson radical (the maximal ideal) is nil, and $ann(N)\subseteq N$ trivially (as long as $N$ is nonzero, which it is in these examples. Otherwise we are looking at a field.)

The only examples I've seen that aren't $0$-(Krull) dimensional are based on a construction which uses a valuation domain $D$, its field of fractions $Q$, and the $D$ module $M=Q/D$ in a trivial extension $R=D(+)M$ whose ideals are linearly ordered. The problem with this construction is that $0(+)M=N$ is the nilradical, $N$ is a faithful $D$ module, and $N^2=\{0\}$, which implies that $ann(N)=N$ (in $R$.)

Other than that construction, I'm not sure how to produce local, dual rings with nonzero Krull dimension.

(NB: to me, local means "has a unique maximal ideal," no Noetherian assumption.)

• I might be missing something: isn't it true that any field is a local and dual ring? Then fields would form a family of examples. – Pierre-Guy Plamondon May 21 '15 at 12:20
• @Pierre-GuyPlamondon What you said is true, but a field has Krull dimension zero, so it doesn't satisfy the requirement of having nonzero Krull dimension. – rschwieb May 21 '15 at 13:30
• That is true. I don't see another example at the moment. Perhaps the condition on the Krull dimension should be added in the statement of your question? – Pierre-Guy Plamondon May 21 '15 at 13:34
• @Pierre-GuyPlamondon Oh, I see what you mean. I actually forgot that fields are exceptional in my discussion since the annihilator of N isn't proper. You're right that I have to eliminate them manually. Among nonfields, Krull dimension > 0 is necessary, and that is what I had been thinking of. Thanks for catching that before it went too far. In questions with a lot of hypotheses, it's very annoying to have left out a detail like that. – rschwieb May 21 '15 at 14:03
• For those following: I've crossposted it to mathoverflow. I'm currently trying a bounty on that version of the question. – rschwieb Jul 16 '15 at 15:46


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