text:
# Prob. 10, Sec. 4.2 in Kreyszig's functional analysis book: There is a linear functional for every sublinear functional …

If $p$ is a sublinear functional on a real vector space $X$, then there exists a linear functional $\tilde{f}$ on $X$ such that $-p(-x) \leq \tilde{f}(x) \leq p(x)$ for all $x \in X$.

How to prove this result?

For all $x, y \in X$, we have $p(x+y) \leq p(x) + p(y)$.

And, for all $x \in X$ and for all $\alpha \in \mathbb{R}$ such that $\alpha > 0$, we have $p(\alpha x) = \alpha p(x)$.

These two conditions imply that $p(\theta) = 0$, where $\theta$ denotes the zero vector in $X$, and $-p(-x) \leq p(x)$ for all $x \in X$.

What next?

How to proceed from here?

## 1 Answer

Take any non-zero $x\in X$ and let $Y=Span\{x\}$. Now define a linear functional $f$ on $Y$ as follows $$f(\alpha x) =\alpha p(x).$$ If $\alpha >0$ then $$f(\alpha x) = \alpha p(x) = p(\alpha x),$$and if $\alpha <0$, then \begin{align}f(\alpha x) &= \alpha p(x)\\ & \leq -\alpha p(-x) & & (\text{because $-p(-x)\leq p(x)$ and $\alpha<0$})\\ & = p(\alpha x). \end{align} Therefore, $f(y) \leq p(y)$ for all $y\in Y$. Now by Hahn-Banach Theorem you can extend $f$ to a linear functional $\tilde{f}$ on $X$ such that $\tilde{f}(x) \leq p(x)$ for all $x\in X$.

Moreover, by linearity of $\tilde{f}$ you get that $-\tilde{f}(x) = \tilde{f}(-x) \leq p(-x) \Rightarrow \tilde{f}(x) \geq -p(-x)$. Combining these things together gives $-p(-x) \leq \tilde{f}(x) \leq p(x)$ for all $x\in X$.

• thanks. So nice of you! If you don't mind my asking this, are you answering my questions by consulting some anciliary material? Or, are you answering these questions just off-hand? – Saaqib Mahmood Jun 7 '15 at 18:43
• I solved these questions when I was learning functional analysis from Kreyszig....and your questions help me to revise the material.... – Urban PENDU Jun 7 '15 at 19:49
• wonderful. Did you solve them on your own? Or, did you have some tutorial support? How much of Kreyszig's book have you studied in class? And how much of it have you learnt by yourself? – Saaqib Mahmood Jun 7 '15 at 20:32
• kreyszig was not followed in the class...I did it by myself. I like kreyszig's presentation of the subject. In class we followed Conway's book on functional analysis – Urban PENDU Jun 7 '15 at 20:50

format: plain


text:
IWOTA 2019

International Workshop on
Operator Theory and its Applications

July 22-26, 2019
Instituto Superior Técnico
Lisbon, Portugal

# Abstracts

## Type of sessions Plenary and semi-plenary Plenary Semi-plenary Analysis and Algebraic Geometry for Operator Variables Analysis and Synthesis for Operator Algebras Free Analysis and Free Probability Functional calculus, spectral sets and constants Gabor Analysis and Noncommutative Geometry Geometry of linear operators and operator algebras Hypercomplex Analysis and Operator Theory Integral Operators and Applications Linear Operators and Function Spaces Matrix Theory and Control Multivariable Operator Theory Operators of Harmonic Analysis, Related Function Spaces and Applications Operators on Reproducing Kernel Hilbert Spaces Operator Theoretical Methods in Mathematical Physics Order preserving operators on cones and applications Preserver Problems in Operator Theory and Functional Analysis Random Matrix Theory Representation Theory of Algebras and Groups Semigroups and Evolution Equations Spectral Theory and Differential Operators Toeplitz Operators, Convolution type Operators and Operator Algebras Truncated Moment Problems Truncated Moment Problems

Raúl E. Curto
University of Iowa

## Bivariate truncated moment problems with algebraic variety in the nonnegative quadrant of $\mathbb{R}^2$

We consider truncated moment problems associated with algebraic varieties in the nonnegative quadrant of $\mathbb{R}^2$. We focus our attention on the interactions between two related problems, as follows.

1. The Subnormal Completion Problem (SCP) for $2$-variable weighted shifts: We use tools and techniques from the theory of truncated moment problems to give a general strategy to solve SCP. We then show that when all quadratic moments are known (equivalently, when the initial segment of weights consists of five independent data points), the natural necessary conditions for the existence of a subnormal completion are also sufficient. To calculate explicitly the associated Berger measure, we compute the algebraic variety of the associated truncated moment problem; it turns out that this algebraic variety is precisely the support of the Berger measure of the subnormal completion.
2. One-step extensions of $2$-variable weighted shifts: We provide necessary and sufficient conditions for the subnormality of such extensions, by using backward extensions, disintegration-of-measure techniques, and $k$-hyponormality techniques from the theory of $2$-variable weighted shifts. We apply our results to solve an interpolation problem for measures on $\mathbb{R}^2$.

The talk is based on joint work with S. H. Lee and J. Yoon.

Philipp di Dio
TU Berlin

## Carathéodory Numbers and Reconstruction of Measures from Moments

Joint Work with Mario Kummer and Konrad Schmüdgen.

We present new lower bounds on the Caratheodory numbers and their asymthotic behavior. By Richters Theorem (1957) every truncated moment functional is a conic combination of point evaluations and the Caratheodory number is the minimal number of point evaluations required to represent a (or all) truncated moment functional(s). We show that the Caratheodory number is cursed by high dimensions, i.e., for any given degree $d$ and $a \gt 0$ there is a natural number $n$ and a truncated moment functional $L$ which needs at least $(1-a)*\binom{n+d}{n}$ point evaluations.

We introduce the concept of a derivative of a (truncated moment) functional and show how this unified theory provides easy and efficient proofs and methods to reconstruct shapes, functions, and measures from their moments.

Lawrence Fialkow
State University of New York at New Paltz

## The core variety and conical representations

This is joint work with Grigoriy Blekherman (Georgia Tech. Univ.). Let $s$ be a truncated multisequence corresponding to $n$-variable monomials, and let $L$ be the Riesz functional associated to $s$. In previous work [arXiv:1804:04276, 2018] we used an iterative geometric construction to associate to $L$ a sequence of algebraic sets in $\mathbb{R}^{n}$, $S_{0} \supseteq S_{1} \supseteq \cdots$, such that $L$ has a representing measure if and only if the sequence stabilizes at a nonempty set $S_{k} = S_{k+1} = \cdots$, called the core variety of $L$, $CV(L)$. In this case, $CV(L)$ is precisely the union of supports of all finitely atomic representing measures for $L$. This result applies more generally when $L$ acts on a finite dimensional vector space of Borel measurable functions on a $T_{1}$ topological space. In the present work we extend the idea of the core variety so as to provide a test for membership in a prescribed convex cone. Let $T$ be a subset of a finite dimesnional real vector space $V$, and let $C$ be the conical hull of $T$. Given $L$ in $V$, we use an iterative geometric construction to define the core variety $CV(L)$ to be a subset of $T$. The main result is that $L$ belongs to $C$ if and only if the iterative procedure stabilizes at nonempty subset. In this case, $CV(L)$ consists of those elements of $T$ which appear in some representation of $L$ as a conical combination of elements of $T$.

Jean Pierre Gabardo
McMaster University

## A factorization problem related to the convolution of positive definite functions.

Let $G$ be one of the classical locally compact abelian groups: $\mathbb{Z}_N^d$, $\mathbb{Z}^d$, $\mathbb{T}^d$ or $\mathbb{R}^d$.

Suppose that  $U$ is an open subset of $G$ with finite Haar measure and that $U$ is symmetric in the sense that $0\in U$ and that $-x\in U$ whenever  $x\in U$. We will discuss the problem of factorizing the constant function $1$ on $G$ as the convolution of two positive definite objects on $G$, one being a continuous positive definite function which is identically zero outside of $U$ and the other a positive definite function (or distribution depending on the group) supported on the set $\{0\}\cup (G\setminus U)$. We will provide a sufficient condition for the problem to be solvable and present some applications of our result.

Didier Henrion
LAAS-CNRS; University of Toulouse

## Tractable semi-algebraic approximation using Christoffel-Darboux kernel

We provide a new method to approximate a (possibly discontinuous) function using Christoffel-Darboux kernels. Our knowledge about the unknown multivariate function is in terms of finitely many moments of the Young measure supported on the graph of the function. Such an input is available when approximating weak (or measure-valued) solution of optimal control problems, entropy solutions to non-linear hyperbolic PDEs, or using numerical integration from finitely many evaluations of the function. While most of the existing methods construct a piecewise polynomial approximation, we construct a semi-algebraic approximation whose estimation and evaluation can be performed efficiently. An appealing feature of this method is that it deals with non-smoothness implicitly so that a single scheme can be used to treat smooth or non-smooth functions without any prior knowledge. On the theoretical side, we prove pointwise convergence almost everywhere as well as convergence in $L^1$ under broad assumptions. Using more restrictive assumptions, we obtain explicit convergence rates. We illustrate our approach on various example from control and approximation. In particular we observe empirically that our method does not suffer from the the Gibbs phenomenon when approximating discontinuous functions.

Joint work with Jean Bernard Lasserre, Swann Marx, Edouard Pauwels and Tillmann Weisser.

David Kimsey
Newcastle University

## On a minimal solution of the indefinite multidimensional truncated moment problem

Given a truncated multisequence $s$ and non-negative integers $\kappa_{\pm}$, we exhibit necessary and sufficient conditions for $s$ to have a representing measure $\mu = \mu_+ - \mu_-$, where ${\rm card}\, {\rm supp} \, \mu_{\pm} = \kappa_{\pm}$. We shall see that necessary and sufficient conditions can be formulated in terms of a rank preserving Hankel extension asuch that the polynomial ideal which models the aforementioned linear dependence is real radical. In the case that $\kappa_{-} = 0$, then our main result collapses to Curto and Fialkow's well-known flat extension theorem. The proof of the main result relies on some theory of Pontryagin spaces and also some basic results in commutative algebra.

Tobias Kuna

## On truncated discrete moment problems

The discrete truncated moment problem considers the question whether given a discrete subsets $K \subset \mathbb{R}^n$ and a collection of real numbers one can find a measure supported on $K$ whose (power) moments (up to degree $d$) are exactly these numbers. In the case $n=1$ I will present  a minimal set of necessary and sufficient conditions for the existence of such measures. I will discuss where we stand in the case $n \gt 1$, $K =\mathbb{Z}^n$ and $d=2$. This simple problem is surprisingly hard and not treatable with known techniques. Applications to the truncated moment problem for point processes, the so-called relizability or representability problem are given. This is a joint work with M. Infusino, J. Lebowitz and E. Speer.

David de Laat
TU Delft

## Pair correlation estimates for the zeros of the zeta function via sum-of-squares representations

In this talk I will explain how sum-of-squares characterizations and semidefinite programming can be used to obtain improved bounds for quantities related to zeros of the Riemann zeta function. This is based on Montgomery's pair correlation approach. I will show how this connects to the sphere packing problem, and speculate about future improvements.

Joint work with Andrés Chirre and Felipe Gonçalves.

Swann Marx
LAAS-CNRS

## A moment approach for entropy solutions to scalar conservation laws.

In this talk, we will propose a new numerical scheme, based on the so called Lasserre hierarchy, which solves scalar conservation laws. Our approach is based on a very weak notion of solution introduced by DiPerna in 1985, which is called entropy measure-valued solution. Among other nice properties, this formulation is linear in a Borel measure, which is the unknown of the equation, and moreover it is equivalent to the well-known entropy solution formulation. Our aim is to explain that the Lasserre hierarchy allows to solve such a linear equation without relying on a mesh, but rather by truncating the moments of the measure under consideration up to a certain degree.

Maria João Oliveira
Universidade Aberta; CMAFcIO, University of Lisbon

## Bogoliubov generating functionals for interacting particle systems in the continuum

One presents an overview how correlation measures (factorial moment measures) and related generating functions can be used to study the time evolution of an interacting particle system in the continuum.

Rajae Ben Taher
University Moulay Ismail, Faculty of Science, Department of Mathematics, Laboratory of Mathematics and their Applications

## A combinatorial expression for the $2$ variable moment sequence via Fibonacci sequence

In this talk, we are going to exploit the combinatorial expression of generalized Fibonacci sequences. More precisely, we manage to obtain the combinatorial expression for each term of the $2$-variable moment sequence, which admits a finitely atomic representing measure.

Martin Venker
Ruhr University Bochum

## On the Random Moment Problem

The random moment problem is concerned with determining typical behavior of moment sequences by studying appropriate moment spaces equipped with probability distributions. We consider random moment sequences of probability measures on a subset $E$ of the real line in the three classical cases of $E$ being the unit interval, the half-line and the whole real line, respectively. We find, depending on $E$, the moments of the families of Kesten-McKay-, Marchenko-Pastur- and semicircle distribution being typical, respectively. Special emphasis is given to universality questions, i.e. the question how typical these three families are. Moreover, we determine typical moment sequences if some moments are known a priori.


text:
location:  Publications → journals
Search results

Search: All articles in the CJM digital archive with keyword embedding

 Expand all        Collapse all Results 1 - 7 of 7

1. CJM Online first

Ostrovskii, Mikhail; Randrianantoanina, Beata
 Metric spaces admitting low-distortion embeddings into all $n$-dimensional Banach spaces For a fixed $K\gg 1$ and $n\in\mathbb{N}$, $n\gg 1$, we study metric spaces which admit embeddings with distortion $\le K$ into each $n$-dimensional Banach space. Classical examples include spaces embeddable into $\log n$-dimensional Euclidean spaces, and equilateral spaces. We prove that good embeddability properties are preserved under the operation of metric composition of metric spaces. In particular, we prove that $n$-point ultrametrics can be embedded with uniformly bounded distortions into arbitrary Banach spaces of dimension $\log n$. The main result of the paper is a new example of a family of finite metric spaces which are not metric compositions of classical examples and which do embed with uniformly bounded distortion into any Banach space of dimension $n$. This partially answers a question of G. Schechtman. Keywords:basis constant, bilipschitz embedding, diamond graph, distortion, equilateral set, ultrametricCategories:46B85, 05C12, 30L05, 46B15, 52A21

2. CJM 2015 (vol 67 pp. 1046)

Dubickas, Arturas; Sha, Min; Shparlinski, Igor
 Explicit Form of Cassels' $p$-adic Embedding Theorem for Number Fields In this paper, we mainly give a general explicit form of Cassels' $p$-adic embedding theorem for number fields. We also give its refined form in the case of cyclotomic fields. As a byproduct, given an irreducible polynomial $f$ over $\mathbb{Z}$, we give a general unconditional upper bound for the smallest prime number $p$ such that $f$ has a simple root modulo $p$. Keywords:number field, $p$-adic embedding, height, polynomial, cyclotomic fieldCategories:11R04, 11S85, 11G50, 11R09, 11R18

3. CJM 2014 (vol 67 pp. 810)

Elliott, George A.; Niu, Zhuang
 All Irrational Extended Rotation Algebras are AF Algebras Let $\theta\in[0, 1]$ be any irrational number. It is shown that the extended rotation algebra $\mathcal B_\theta$ introduced in a previous paper is always an AF algebra. Keywords:irrational rotation algebra, extended irrational rotation algebra, AF-embedding

4. CJM 2010 (vol 63 pp. 436)

Mine, Kotaro; Sakai, Katsuro
 Simplicial Complexes and Open Subsets of Non-Separable LF-Spaces Let $F$ be a non-separable LF-space homeomorphic to the direct sum $\sum_{n\in\mathbb{N}} \ell_2(\tau_n)$, where $\aleph_0 < \tau_1 < \tau_2 < \cdots$. It is proved that every open subset $U$ of $F$ is homeomorphic to the product $|K| \times F$ for some locally finite-dimensional simplicial complex $K$ such that every vertex $v \in K^{(0)}$ has the star $\operatorname{St}(v,K)$ with $\operatorname{card} \operatorname{St}(v,K)^{(0)} < \tau = \sup\tau_n$ (and $\operatorname{card} K^{(0)} \le \tau$), and, conversely, if $K$ is such a simplicial complex, then the product $|K| \times F$ can be embedded in $F$ as an open set, where $|K|$ is the polyhedron of $K$ with the metric topology. Keywords:LF-space, open set, simplicial complex, metric topology, locally finite-dimensional, star, small box product, ANR, $\ell_2(\tau)$, $\ell_2(\tau)$-manifold, open embedding, $\sum_{i\in\mathbb{N}}\ell_2(\tau_i)$Categories:57N20, 46A13, 46T05, 57N17, 57Q05, 57Q40

5. CJM 2008 (vol 60 pp. 961)

Abrescia, Silvia
 About the Defectivity of Certain Segre--Veronese Varieties We study the regularity of the higher secant varieties of $\PP^1\times \PP^n$, embedded with divisors of type $(d,2)$ and $(d,3)$. We produce, for the highest defective cases, a determinantal'' equation of the secant variety. As a corollary, we prove that the Veronese triple embedding of $\PP^n$ is not Grassmann defective. Keywords:Waring problem, Segre--Veronese embedding, secant variety, Grassmann defectivityCategories:14N15, 14N05, 14M12

6. CJM 2004 (vol 56 pp. 1068)

Steinbach, Anja; Van Maldeghem, Hendrik
 Regular Embeddings of Generalized Hexagons We classify the generalized hexagons which are laxly embedded in projective space such that the embedding is flat and polarized. Besides the standard examples related to the hexagons defined over the algebraic groups of type $\ssG_2$, $^3\ssD_4$ and $^6\ssD_4$ (and occurring in projective dimensions $5,6,7$), we find new examples in unbounded dimension related to the mixed groups of type $\ssG_2$. Keywords:Moufang generalized hexagons, embeddings, mixed hexagons, classical, hexagonsCategories:51E12, 51A45

7. CJM 1999 (vol 51 pp. 585)

Mansfield, R.; Movahedi-Lankarani, H.; Wells, R.
 Smooth Finite Dimensional Embeddings We give necessary and sufficient conditions for a norm-compact subset of a Hilbert space to admit a $C^1$ embedding into a finite dimensional Euclidean space. Using quasibundles, we prove a structure theorem saying that the stratum of $n$-dimensional points is contained in an $n$-dimensional $C^1$ submanifold of the ambient Hilbert space. This work sharpens and extends earlier results of G.~Glaeser on paratingents. As byproducts we obtain smoothing theorems for compact subsets of Hilbert space and disjunction theorems for locally compact subsets of Euclidean space. Keywords:tangent space, diffeomorphism, manifold, spherically compact, paratingent, quasibundle, embeddingCategories:57R99, 58A20
 top of page | contact us | privacy | site map |


text:
5

# [-/1.66 Points]DETAILSMY NOTESUse the equation for the energy of the electron In the Bohr model of the atom and the fact that hxR 2.180e-18 to calculate the energy ...

## Question

###### [-/1.66 Points]DETAILSMY NOTESUse the equation for the energy of the electron In the Bohr model of the atom and the fact that hxR 2.180e-18 to calculate the energy of an electron in the given level of each of the following ions This Is equation 2.5 in the paper textbook and can be found by browsing the Fbook- Use notation with two decimal places. For example, 2.34e-22_ Hint: Each of the ions has different number of protons but all have one electronLevel (n)IonEnergy inLi2+

[-/1.66 Points] DETAILS MY NOTES Use the equation for the energy of the electron In the Bohr model of the atom and the fact that hxR 2.180e-18 to calculate the energy of an electron in the given level of each of the following ions This Is equation 2.5 in the paper textbook and can be found by browsing the Fbook- Use notation with two decimal places. For example, 2.34e-22_ Hint: Each of the ions has different number of protons but all have one electron Level (n) Ion Energy in Li2+

#### Similar Solved Questions

##### 44 7125 =90Name pair of supplementary angles- L64 L3 ISoGiven ZI = Z2,tinish the proof that mzI=mSStatementsRcasons GiuoZI-222. 22ez5VLall Aipax 3 . Transitive Property of Angle CongruenceLLSLsmzi=m ZS45 If mZI = 60", then mZ3 + mZS = 12FILL IN YOUR NAMF AND
44 7125 =90 Name pair of supplementary angles- L64 L3 ISo Given ZI = Z2,tinish the proof that mzI=mS Statements Rcasons Giuo ZI-22 2. 22ez5 VLall Aipax 3 . Transitive Property of Angle Congruence LLSLs mzi=m ZS 45 If mZI = 60", then mZ3 + mZS = 12 FILL IN YOUR NAMF AND...
##### Let A be the abelian group generated by some X,Y, Z,W subject to linear relations: 6 X + 24Y + 302 + 18W = 0 18 X + 72Y + 90 2 + 43W = 0 18 X + 74Y + 942 + 112W = 06.[10 Marks]Use row and column operations on the matrix of coefficients of X,YZ,W to find the structure of A as direct sum of cyclic groups_ What is the rank of A? What is the size of the torsion subgroup Ar = T(A)?(q The map 03 A-A such that @s(x) = 3x is homomorphism. Let A[3] and 3A denote respectively the kernel and image of 03 -
Let A be the abelian group generated by some X,Y, Z,W subject to linear relations: 6 X + 24Y + 302 + 18W = 0 18 X + 72Y + 90 2 + 43W = 0 18 X + 74Y + 942 + 112W = 0 6. [10 Marks] Use row and column operations on the matrix of coefficients of X,YZ,W to find the structure of A as direct sum of cyclic ...
##### Find & formula for the general term @h of the sequence continues. assuming the pattern of the first (ew tetins(2' 4' 8 ' 16assume the first term 4aiCheck answcr
Find & formula for the general term @h of the sequence continues. assuming the pattern of the first (ew tetins (2' 4' 8 ' 16 assume the first term 4ai Check answcr...
##### The normality condition satisfied?YesThere is insufficient evidence t0 check the normality condition.The normality condition does not need to be satisfiedWas less than 10% of the population sampled?YesThere insufficient evidence to check this condition. This concition does not reed to be satisfied_Were there more than 10 successes and 10 failures?YesThere insufficient evidence t0 check this condition_This concition does not need t0 be satisfiedb) If we found regression to predict Violent Crime j
the normality condition satisfied? Yes There is insufficient evidence t0 check the normality condition. The normality condition does not need to be satisfied Was less than 10% of the population sampled? Yes There insufficient evidence to check this condition. This concition does not reed to be satis...
##### Use Ihe property of expononts &m .a" cam+n to determine the following procuct:
Use Ihe property of expononts &m .a" cam+n to determine the following procuct:...
##### Determine the period of each function. $$y=\cot (\pi x / 2)$$
Determine the period of each function. $$y=\cot (\pi x / 2)$$...
##### Question 1 of 10Choose the correct order of the numbered statements to put the last four events of photosynthesis in order:1. A photon of light strikes photosystem and allows it to excite the electron:2. The electron transport chain passes the electron from photosystem Il to photosystem3. The excited electron is passed from photosystem to NADPH_4. NADPH and ATP are used in the Calvin cycle to make glucose_2,1,3,4B: 3,1,2,4C. 1,4,3,2D: 1,2,4,3SUBMIT
Question 1 of 10 Choose the correct order of the numbered statements to put the last four events of photosynthesis in order: 1. A photon of light strikes photosystem and allows it to excite the electron: 2. The electron transport chain passes the electron from photosystem Il to photosystem 3. The ex...
##### What is the rute 0f the fornation of B ovcr thc duration of 15 micurz uicz 7nat dccomposition rartion of rcxctunt A; 4 > JB is mointcred GVEr ume_ aperimcntal dot providcd below:Time (miu)0.13 Wmin0.27 Mimin0.089 Wmin0,80 Wrin
What is the rute 0f the fornation of B ovcr thc duration of 15 micurz uicz 7nat dccomposition rartion of rcxctunt A; 4 > JB is mointcred GVEr ume_ aperimcntal dot providcd below: Time (miu) 0.13 Wmin 0.27 Mimin 0.089 Wmin 0,80 Wrin...
##### How would you prepare a 1000 mL ofa 0.1 N solution from a 4.5 N solution?
How would you prepare a 1000 mL ofa 0.1 N solution from a 4.5 N solution?...
##### The value of Pu1(1) Pt(-1) isa. 2b1C= -1d. 11e. 0
The value of Pu1(1) Pt(-1) is a. 2 b1 C= -1 d. 11 e. 0...
##### Find at least two different versions of the periodic table and bring a copy of each to class.a. Write down what you think makes these two versions similar to each other.b. Write down what you think makes these two versions different from each other.
Find at least two different versions of the periodic table and bring a copy of each to class. a. Write down what you think makes these two versions similar to each other. b. Write down what you think makes these two versions different from each other....
##### The sumZr (Zk-1)) Iisa Ieft Riemann sum with subintervals of equal length: The limit of this sum as goes to infinity can be interpreted as definite integral; Express. the limit as definite integral,
The sum Zr (Zk-1)) Iisa Ieft Riemann sum with subintervals of equal length: The limit of this sum as goes to infinity can be interpreted as definite integral; Express. the limit as definite integral,...
##### If ð‘âŠ´ðº and ð¾â‰¤ðº,i. Then ð‘† = {ð‘›ð‘˜: ð‘›âˆˆð‘âˆ§ð‘˜âˆˆð¾} â‰¤ðº.ii. If both subgroups ð» and ð¾ are normal, then ð‘† is also normal.
If ð‘âŠ´ðº and ð¾â‰¤ðº, i. Then ð‘† = {ð‘›ð‘˜: ð‘›âˆˆð‘âˆ§ð‘˜âˆˆð¾} â‰¤ðº. ii. If both subgroups ð» and ð¾ are normal, then ð‘† is also normal....
##### Many Americans complain about being sleep deprived. A team ofpsychologists researched the reasons for this sleep deprivation.After determining that one reason was poor time management, theydevised a program to help people manage their time better. Theyrecruited a random sample of 30 people at a major shopping centerand randomly split them into three groups of size 10. Group 1: thecontrols, received a logbook asking them to record the number ofhours slept for a week, but nothing else. Group 2: th
Many Americans complain about being sleep deprived. A team of psychologists researched the reasons for this sleep deprivation. After determining that one reason was poor time management, they devised a program to help people manage their time better. They recruited a random sample of 30 people at a ...
##### Quantum numbers arise naturally from the mathematics used t0 describe the possible Hales of an electron in an atom The four quantum numbers; the principal quantum number (n), the angular momentum quantum number (2), the magnetic quantum number (m,) and the spin quantum number (m) have strict rules which govern the possible values:Identify all allowable combinations of quantum numbers for an electron_n =3,{=2m =L,msn =5.8 =3.m, fl,ms L.mt ~L;ms2,mg2.M,
Quantum numbers arise naturally from the mathematics used t0 describe the possible Hales of an electron in an atom The four quantum numbers; the principal quantum number (n), the angular momentum quantum number (2), the magnetic quantum number (m,) and the spin quantum number (m) have strict rules ...


text:
×

# ARRP - Editorial

Div1, Div2
Practice

Author: Misha Chorniy
Tester: Lewin Gan

Easy-Medium

# PREREQUISITES:

Sieve of Eratosthenes

# PROBLEM:

You are given an array $A$ with size $N$. For each $K$ between $1$ and $N$ (inclusive), find out if it is possible to partition (split) the array $A$ into $K$ contiguous subarrays such that the sum of elements within each of these subarrays is the same.

# EXPLANATION:

Let $S[i] = \sum_{j=1}^{i} A[j]$. Let's make some observation here now:

• All the values of $S[i]$ will be distinct because all $A[j] > 0$.
• $S[N]$ must be divisible by $K$ if we want to partition the array into $K$ contiguous part.
• Sum of each part will be equal to $\frac{S[N]}{K} = X$ (say).
• For every multiple of $X$ i.e. for every $X*i$ ∀ $1 \le i \le K$ there must exist some $j$ such that $S[j]=X.i$.

Iterate over all the divisors of $S[N]$ that is $\le N$. For every such divisor $K$ we will check if all of the multiples of $\frac{S[N]}{K}$ are present in the prefix sum array or not. Let's make a $cnt[]$ array which stores how many multiples of $\frac{S[N]}{K}$ are present in the prefix sum array in $cnt[K]$. Any $K$ will be good iff $cnt[K]==K$.

From the above observations, $S[j]=\frac{S[N]}{K}.i$ which means $\frac{S[j]}{S[N]}=\frac{i}{K}$. We are going to iterate over $S[j]$, compute the irreducible fraction $\frac{S[j]}{S[N]} =\frac{P}{Q}$. Now we need to increase $cnt[Q.i]$ by $1$ for all those $Q.i$ that are divisors of $S[N]$ and $\le N$, because for every $Q.i$ you get a distinct $P.i$ because of the property that all prefix sums are distinct.

Doing the later step for every $j$ can be costly. Hence, we will use sieve for this purpose. When iterating over $j$, just increment $cnt[Q]$ by $1$ if $Q \le N$. When done iterating over $j$, you can run a sieve-like algorithm for updating the multiples of every $cnt[Q.i]$ which will cost us $O(NlogN)$.

You can refer to the setter's solution for implementation details of this approach.

# ALTERNATE SOLUTION:

Based on above observations, we will try to devise our solution. Iterate over all the divisors of $S[N]$ that is $\le N$. For every such divisor $K$ we will check if all of the multiples of $\frac{S[N]}{K}$ are present in the prefix sum array or not. If all of the multiples are present in the prefix sum array then this $K$ is good. When doing naively, for every $K$ it will require $O(K.logN)$ operations to check if every multiple of $K$ is present in prefix sum array. But creating good test data which costs $O(K.logN)$ for every $K$ is nearly impossible. Hence, in practice, this approach will run a lot fast than expected. Tester's solution uses this idea. You can refer to it for the implementation details.

# Time Complexity:

$O(NlogN)$

# AUTHOR'S AND TESTER'S SOLUTIONS

This question is marked "community wiki".

306719
accept rate: 7%

19.7k350498541

 0 Can anyone explain this through an example? answered 08 Apr '18, 23:43 16 accept rate: 10% 2 Let's consider the first example: 1 4 2 3 5. The array of prefix sums(S) will look like 1 5 7 10 15. Let's make fractions from it: 1/15 5/15 7/15 10/15 15/15. Let's make them irreducible 1/15 1/3 7/15 2/3 1/1. Now consider only denominators which are <= N=5(only they will affect the answer), i.e. (3)1/3 (3)2/3 (1)1/1. Now, for every K=1..N find the number of denominators which are divisors of K. K=1(1), K=2(1), K=3(3), K=4(1), K=5(1). We're interested only in those values of K for which this number is equal to K, i.e 1 and 3. (08 Apr '18, 23:57) mgch6★ Thanks for the explanation. Can you please give me the editorial link of TRS ? https://www.codechef.com/LTIME58A/problems/TRS (09 Apr '18, 00:14) 1 (09 Apr '18, 00:22) mgch6★
 toggle preview community wiki:
Preview

By Email:

Markdown Basics

• *italic* or _italic_
• **bold** or __bold__
• image?![alt text](/path/img.jpg "title")
• numbered list: 1. Foo 2. Bar
• to add a line break simply add two spaces to where you would like the new line to be.
• basic HTML tags are also supported
• mathemetical formulas in Latex between \$ symbol

Question tags:

×15,492
×1,648
×1,176
×301
×68
×47
×1

question asked: 02 Apr '18, 15:56

question was seen: 665 times

last updated: 09 Apr '18, 00:22


text:
Homework Help: Friction acting on a spinning ice skater

1. Nov 26, 2004

angelina

when talking about conservation of angular momentum of a spinning ice skater, the contact surfaces are assumed to be frictionless. why?

2. Nov 26, 2004

Physics_wiz

Well, if there is friction to slow the skater down then his/her velocity would go down and decrease the angular momentum so it wouldn't be conserved.

3. Nov 26, 2004

Tide

A frictionless surface is assumed simply because it's a lot easier to analyze. However, the inclusion of friction does not alter the fact that total angular momentum is conserved.

4. Nov 26, 2004

Physics_wiz

Opps. Sorry, Tide probably knows what he's talking about more than me. Real sorry about that, but I just looked at the equation and saw mvr. r and m are constants so I thought, if v goes down, momentum goes down....eh I'm wrong anyways; listen to Tide.

5. Nov 27, 2004

angelina

*total* angular momentum means the system of the skater alone or the system of the skater + ice floor?

also, say the spinning direction is on the x-z plane, then the friction acting on will be providing a torque along the x-direction. my question is, how does this frictional torque affecting the angular momentum of the skater??

Last edited: Nov 27, 2004
6. Nov 27, 2004

Staff: Mentor

If there is friction between the ice and skate, then the ice will apply a torque to the skater, reducing her angular momentum. Of course, if you include both the skater and the ice floor in your system, then angular momentum is conserved.

7. Nov 27, 2004

angelina

then my question will become - is it true that as longer as there's external torque, no matter this torque is acting about the same axis as the rotation or about a different axis, angular momentum is not conserved??

8. Nov 27, 2004

Staff: Mentor

Right. If there is an net external torque, then total angular momentum is not conserved. But it is often the case that you can conserve angular momentum about a particular axis.

In the case of the spinning skater, her axis of rotation is vertical, and, assuming no friction, there is no torque about that vertical axis. So her angular momentum about that axis is conserved.

9. Nov 28, 2004

angelina

for the case of the spinning skater, if friction exists, which axis will its torque act about? the same vertical (y-axis) or the z-axis or both??

10. Nov 28, 2004

Staff: Mentor

If the skater spins about the vertical axis, then the friction (which opposes the motion of her skates) will exert a torque about that same vertical axis.

11. Nov 28, 2004

Andre

And what happens to the "lost" momentum due to the friction? It is added to the rotation of the Earth.

Actually the law of conservation of momentum is applying only to the complete universe, not individual systems. Systems interact. The moon and earth exchange momentum due to torque forces exerted by gravity.


text:
# Keck/OSIRIS Paβ High-contrast Imaging and Updated Constraints on PDS 70b

@article{Uyama2021KeckOSIRISPH,
title={Keck/OSIRIS Pa$\beta$ High-contrast Imaging and Updated Constraints on PDS 70b},
author={Taichi Uyama and Chen Xie and Yuhiko Aoyama and Charles A. Beichman and Jun Hashimoto and Ruobing Dong and Yasuhiro Hasegawa and Masahiro Ikoma and Dimitri Mawet and Michael W. McElwain and Jean-Baptiste Ruffio and Kevin R. Wagner and Jason J. Wang and Yifan Zhou},
journal={The Astronomical Journal},
year={2021},
volume={162}
}
• T. Uyama, Chen Xie, +11 authors Yifan Zhou
• Published 14 September 2021
• Physics
• The Astronomical Journal
We present a high-contrast imaging search for Paβ line emission from protoplanets in the PDS 70 system with Keck/OSIRIS integral field spectroscopy. We applied the high-resolution spectral differential imaging technique to the OSIRIS J-band data but did not detect the Paβ line at the level predicted using the parameters of Hashimoto et al. (2020). This lack of Paβ emission suggests the MUSE-based study may have overestimated the line width of Hα. We compared our Paβ detection limits with the…
2 Citations
Characterizing the Protolunar Disk of the Accreting Companion GQ Lupi B
GQ Lup B is a young and accreting, substellar companion that appears to drive a spiral arm in the circumstellar disk of its host star. We report high-contrast imaging observations of GQ Lup B with
Accreting protoplanets: Spectral signatures and magnitude of gas and dust extinction at H α
Context. Accreting planetary-mass objects have been detected at H α, but targeted searches have mainly resulted in non-detections. Accretion tracers in the planetary-mass regime could originate from

## References

SHOWING 1-10 OF 32 REFERENCES
Characterization of the gaseous companion κ Andromedae b - New Keck and LBTI high-contrast observations
Context. We previously reported the direct detection of a low mass companion at a projected separation of 55 2 AU around the B9 type star Andromedae. The properties of the system (mass ratio,
Constraining PDS 70b’s Formation Mechanism with Multi-hydrogen-emission Observations
We present our Keck/OSIRIS observations of the Paβ emission line (1.282 μm) to investigate accretion mechanisms of PDS 70 planetary system. Our spectral differential imaging reduction to remove the
Constraining Planetary Gas Accretion Rate from Hα Line Width and Intensity: Case of PDS 70 b and c
• Physics
The Astrophysical Journal
• 2019
Recent observations of protoplanets embedded in circumstellar disks have shed light on the planet formation process. In particular, detection of hydrogen Balmer-line (Hα) emission gives direct
Magellan Adaptive Optics Imaging of PDS 70: Measuring the Mass Accretion Rate of a Young Giant Planet within a Gapped Disk
PDS 70b is a recently discovered and directly imaged exoplanet within the wide (40 au) cavity around PDS 70. Ongoing accretion onto the central star suggests that accretion onto PDS 70b may also be
Molecular mapping of the PDS70 system
Context. Determining the chemical properties of the atmosphere of young forming gas giants might shed light on the location their formation occurred and the mechanisms involved. Aims. Our aim was to
Hubble Space Telescope UV and Hα Measurements of the Accretion Excess Emission from the Young Giant Planet PDS 70 b
Recent discoveries of young exoplanets within their natal disks offer exciting opportunities to study ongoing planet formation. In particular, a planet’s mass accretion rate can be constrained by
Detection and Characterization of Exoplanets and Disks using Projections on Karhunen-Loeve Eigenimages
• Physics
• 2012
We describe a new method to achieve point spread function (PSF) subtractions for high- contrast imaging using Principal Component Analysis (PCA) that is applicable to both point sources or extended
Characterizing and Improving the Data Reduction Pipeline for the Keck OSIRIS Integral Field Spectrograph
OSIRIS is a near-infrared (1.0--2.4 $\mu$m) integral field spectrograph operating behind the adaptive optics system at Keck Observatory, and is one of the first lenslet-based integral field
The Optical to Mid-infrared Extinction Law Based on the APOGEE, Gaia DR2, Pan-STARRS1, SDSS, APASS, 2MASS, and WISE Surveys
• Physics
The Astrophysical Journal
• 2019
A precise interstellar dust extinction law is critically important to interpret observations. There are two indicators of extinction: the color excess ratio (CER) and the relative extinction.
Two accreting protoplanets around the young star PDS 70
Newly forming protoplanets are expected to create cavities and substructures in young, gas-rich protoplanetary disks1–3, but they are difficult to detect as they could be confused with disk features


text:
News: IT'S THE 2ND ANNUAL GUATEMALA LIBRARY PROJECT BOOK DRIVE!    LOOKING FOR DONATIONS OF SCIENCE BOOKS THIS YEAR.    Check it out in the "Extending the Hand of Kindness" folder or here: http://www.etiquettehell.com/smf/index.php?topic=139832.msg3372084#msg3372084

• December 15, 2017, 02:02:51 PM

### Author Topic: "I'm never shopping THERE again!" Share your story!  (Read 2677285 times)

0 Members and 5 Guests are viewing this topic.

#### JolieFille

• Member
• Posts: 296
• I'm a Pixie! With Fangs! =P
##### Re: "I'm never shopping THERE again!" Share your story!
« Reply #4620 on: September 10, 2013, 11:50:40 AM »
If I could not use FedEx ever again I wouldn't.  ;

On Wednesday I had a very expensive package out for delivery. An Alienware computer. I waited. The guy shows up and starts digging about in his truck. Finally he looks at me, shrugs, and says he can't find it he'll be back later.

What?! Long conversation with customer support later and he shows back up in 20 minutes. He was pissed, and I could hear his supervisor on the phone and he didn't sound happy. I don't know what the issue was, I mean my box was only 20lbs and they load their truck in delivery order for the most part. I had no guarantee that he'd be back. He was even ruder when he took my ID # and saw that I'm pretty young and I could detect a bit of 'how can she afford this!?' attitude from him.

I think the issue was the driver was lazy and couldn't be bothered to keep looking glad you got your package though!

Heard there was a big scam going with hard to get Wii units years ago.  Delivery drivers were faking delivery attempts and after the 3rd attempt the boxes were sent back to the seller.  Except the packages were never sent, they "disappeared" in the system.  Turns out delivery employees were taking them for personal use or resale.  The merchant was stuck making a claim or taking the loss.

I wonder if your driver was hoping to eventually make your Alien "his"  .

And here I thought I was just being uncharitable having that thought.

I have to say after I got the box I was wondering the same thing. They don't use discreet boxes for that sort of computer.

My biggest worry was, the guy on the phone said that he had to come back since he never scanned the box. I was wondering if that's what he was doing while he was in there. It was seriously the strangest delivery experience I've had so far.

I honestly prefer ups or USPS. My mail lady will hand me any packages and the ups guy has been delivering to my house for years.

#### Ser Lucien Liliane

• The Unsleeping Translator
• Member
• Posts: 1226
##### Re: "I'm never shopping THERE again!" Share your story!
« Reply #4621 on: September 10, 2013, 08:27:54 PM »
GameStop is coming very, very, very, very close to being put on my "you do not deserve my business" list...they only aren't there because they are the ONLY place I can get specific games...

They have charged me $50 for absolutely nothing. I haven't ordered anything lately - all I have in is two preorders that don't even come out till next year! - I was never sent any sort of confirmation email, there's nothing in my order history. Just this sudden unexpected$50 charge that I never would have even KNOWN about if I hadn't tried to buy something tonight and had my card declined. I swear, I have never been this angry in my life.

I did contact them - I can't do it by phone unfortunately, so I had to go through their email form and I don't expect I'll get a response. I'm not sure what else I can do at this point, except see if I actually do end up receiving some sort of package.

(And no, before anyone jumps to the scary conclusion, I'm positive no one's got my card info.)
"Ah, yes. I forgot you've taken levels in Defeating Paperwork."

#### NyaChan

• Member
• Posts: 3668
##### Re: "I'm never shopping THERE again!" Share your story!
« Reply #4622 on: September 10, 2013, 08:34:20 PM »
GameStop is coming very, very, very, very close to being put on my "you do not deserve my business" list...they only aren't there because they are the ONLY place I can get specific games...

They have charged me $50 for absolutely nothing. I haven't ordered anything lately - all I have in is two preorders that don't even come out till next year! - I was never sent any sort of confirmation email, there's nothing in my order history. Just this sudden unexpected$50 charge that I never would have even KNOWN about if I hadn't tried to buy something tonight and had my card declined. I swear, I have never been this angry in my life.

I did contact them - I can't do it by phone unfortunately, so I had to go through their email form and I don't expect I'll get a response. I'm not sure what else I can do at this point, except see if I actually do end up receiving some sort of package.

(And no, before anyone jumps to the scary conclusion, I'm positive no one's got my card info.)

You should probably challenge the charge with your credit card company.  They'll look into it for you.

#### Jones

• Member
• Posts: 2514
##### Re: "I'm never shopping THERE again!" Share your story!
« Reply #4623 on: September 10, 2013, 08:35:38 PM »
GameStop is coming very, very, very, very close to being put on my "you do not deserve my business" list...they only aren't there because they are the ONLY place I can get specific games...

They have charged me $50 for absolutely nothing. I haven't ordered anything lately - all I have in is two preorders that don't even come out till next year! - I was never sent any sort of confirmation email, there's nothing in my order history. Just this sudden unexpected$50 charge that I never would have even KNOWN about if I hadn't tried to buy something tonight and had my card declined. I swear, I have never been this angry in my life.

I did contact them - I can't do it by phone unfortunately, so I had to go through their email form and I don't expect I'll get a response. I'm not sure what else I can do at this point, except see if I actually do end up receiving some sort of package.

(And no, before anyone jumps to the scary conclusion, I'm positive no one's got my card info.)

You should probably challenge the charge with your credit card company.  They'll look into it for you.
It isn't time to update the annual membership is it?
“A real desire to believe all the good you can of others and to make others as comfortable as you can will solve most of the problems.” CS Lewis

#### Ser Lucien Liliane

• The Unsleeping Translator
• Member
• Posts: 1226
##### Re: "I'm never shopping THERE again!" Share your story!
« Reply #4624 on: September 10, 2013, 08:48:24 PM »
GameStop is coming very, very, very, very close to being put on my "you do not deserve my business" list...they only aren't there because they are the ONLY place I can get specific games...

They have charged me $50 for absolutely nothing. I haven't ordered anything lately - all I have in is two preorders that don't even come out till next year! - I was never sent any sort of confirmation email, there's nothing in my order history. Just this sudden unexpected$50 charge that I never would have even KNOWN about if I hadn't tried to buy something tonight and had my card declined. I swear, I have never been this angry in my life.

I did contact them - I can't do it by phone unfortunately, so I had to go through their email form and I don't expect I'll get a response. I'm not sure what else I can do at this point, except see if I actually do end up receiving some sort of package.

(And no, before anyone jumps to the scary conclusion, I'm positive no one's got my card info.)

You should probably challenge the charge with your credit card company.  They'll look into it for you.
It isn't time to update the annual membership is it?

No, I just renewed in May and that's only \$15.

I'm giving them a couple days to respond, and then I'm going to go to the bank and let them raise holy Cain. I suppose the most annoying part is the bit of my mind that says "well, you might have had an order open..." when I darn well know I did NOT...
"Ah, yes. I forgot you've taken levels in Defeating Paperwork."

#### It's good to be Queen

• Member
• Posts: 840
##### Re: "I'm never shopping THERE again!" Share your story!
« Reply #4625 on: September 10, 2013, 08:58:03 PM »
UPS MyChoice has been my lifesaver.  They send me a notification the day before I am supposed to get a package and I can either tell them where to leave it or tell them to hold it at the depot for pickup.  You sign up online and it is free.

#### BB-VA

• Member
• Posts: 847
##### Re: "I'm never shopping THERE again!" Share your story!
« Reply #4626 on: September 10, 2013, 09:14:36 PM »
FedEx, in my experience, does a wonderful job delivering to businesses and in city settings.  But when you live 5 miles from the city limits and a tenth of a mile from the county road, not so much.  I also wish they would just give me a call and I'll pick up the package at the hub.

The absolute worst, IMO, is DHL.  At least FedEx can find my house!!

"The Universe puts us in places where we can learn. They are never easy places, but they are right. Wherever we are, it's the right place and the right time. Pain that sometimes comes is part of the process of constantly being born."
- Delenn to Sheridan: "Babylon 5 - Distant Star"

#### MommyPenguin

• Member
• Posts: 4130
##### Re: "I'm never shopping THERE again!" Share your story!
« Reply #4627 on: September 10, 2013, 09:26:06 PM »
I feel sort of bad, sometimes, because I hear so many bad stories about delivery companies, and we have such good luck in general!  We order a *ton* of stuff from Amazon--we often have a delivery every few days.  They always arrive, safe, and in good condition.  FedEx, UPS, even the mail delivery.

We did have an issue in our previous house with USPS, though.  We were working on the roof over the door and the gutters were removed, so the little outside mailbox would get wet.  When we went on vacation, we put a hold on our mail, asking them to hold it and then delivery it on Saturday.  They'd deliver it Friday, in the rain, and it would all get soaking wet.  So the next time, we were going to get home on Monday, so I asked them to deliver it on Wednesday, giving myself a buffer just in case.  Nope, didn't work.  They still delivered it on Monday (or maybe Saturday?) and it was soaking wet when we got home.  <sigh>  The next time I added like 4 days of buffer and it arrived the day after we got home, finally.
Emily is 10 years old!  1/07
Jenny is 8 years old!  10/08
Charlotte is 7 years old!  8/10
Megan is 4 years old!  10/12
Lydia is 2 years old!  12/14
Baby Charlie expected 9/17

#### PastryGoddess

• Member
• Posts: 6399
##### Re: "I'm never shopping THERE again!" Share your story!
« Reply #4628 on: September 10, 2013, 09:26:44 PM »
UPS MyChoice has been my lifesaver.  They send me a notification the day before I am supposed to get a package and I can either tell them where to leave it or tell them to hold it at the depot for pickup.  You sign up online and it is free.

What is this choice you speak of???

#### suzieQ

• Member
• Posts: 528
##### Re: "I'm never shopping THERE again!" Share your story!
« Reply #4629 on: September 10, 2013, 10:11:21 PM »
UPS MyChoice has been my lifesaver.  They send me a notification the day before I am supposed to get a package and I can either tell them where to leave it or tell them to hold it at the depot for pickup.  You sign up online and it is free.

What is this choice you speak of???

#### Slartibartfast

• Member
• Posts: 10793
##### Re: "I'm never shopping THERE again!" Share your story!
« Reply #4630 on: September 11, 2013, 12:08:37 AM »
I ordered something from Amazon which turned out to be not what I wanted, so I had to return it.  The only option was UPS - I don't think I've ever actually shipped anything from other than the post office, so I wouldn't know where to go.  Luckily, Amazon/UPS offered home pick-up - all I had to do was to have it in a box and they'd show up with a shipping label and everything, so it was free.  Sounds good!

Yeah, the confirmation email I got told me they'd be by my house sometime in the next three days, and to have the box ready.  That's "sometime 8 AM - 8 PM," not any specific hours, and no, they didn't call ahead or give any warning.  I was lucky that the driver did show up the next day at a time I was home - I wasn't planning to sit around for three days straight waiting for them!

#### jedikaiti

• Swiss Army Nerd
• Member
• Posts: 2799
• A pie in the hand is worth two in the mail.
##### Re: "I'm never shopping THERE again!" Share your story!
« Reply #4631 on: September 11, 2013, 12:17:40 AM »
You couldn't just drop it off?

I once ordered a few items from a website that sells pilot supplies - aviation headsets, flight bags, flying charts, etc.

I got a box with a 3-roll of white curling ribbon.

Seems their warehouse contractor made a mistake. They told me to keep the ribbon and they had the warehouse re-ship the correct stuff. <G>
What part of v_e = \sqrt{\frac{2GM}{r}} don't you understand? It's only rocket science!

"The problem with re-examining your brilliant ideas is that more often than not, you discover they are the intellectual equivalent of saying, 'Hold my beer and watch this!'" - Cindy Couture

#### Pen^2

• Member
• Posts: 857
##### Re: "I'm never shopping THERE again!" Share your story!
« Reply #4632 on: September 11, 2013, 12:24:30 AM »
I ordered something from Amazon which turned out to be not what I wanted, so I had to return it.  The only option was UPS - I don't think I've ever actually shipped anything from other than the post office, so I wouldn't know where to go.  Luckily, Amazon/UPS offered home pick-up - all I had to do was to have it in a box and they'd show up with a shipping label and everything, so it was free.  Sounds good!

Yeah, the confirmation email I got told me they'd be by my house sometime in the next three days, and to have the box ready.  That's "sometime 8 AM - 8 PM," not any specific hours, and no, they didn't call ahead or give any warning.  I was lucky that the driver did show up the next day at a time I was home - I wasn't planning to sit around for three days straight waiting for them!

Ooh I can't stand this. I really feel it isn't reasonable to expect people to be at home all day for several days for something like this. If you think it's okay to expect me to take three days off work for something that could easily be organised with a more specific time, then I think it's okay to expect you to reimburse me the three days of wages I'll lose. Plumbers, handymen, etc. are more reasonable because their schedule changes during the day based on how long each job takes--but generally it's a "I'll be over sometime Tuesday afternoon, between 2pm and 7pm", not three flipping days. Although I did once have an electrician who kept insisting that he'd need me to keep the whole day clear, and then wouldn't find time to show up, and would need me to take yet another day off, for several days. My job just isn't that flexible: I can't just not come in at a day's notice, and this isn't unusual for many occupations.

He wasn't my electrician for very long.

Not every household has an adult in it who neither works nor has no commitments during the day. I would suspect that most homes, actually, don't.

• Member
• Posts: 5872
##### Re: "I'm never shopping THERE again!" Share your story!
« Reply #4633 on: September 11, 2013, 05:54:58 AM »
There is a new metal smithing magazine, Australian Goldsmith. Stay away - the people there are jerks.

I was looking over their website, wondering if there was a way to buy a single issue instead of subscribing. I came across their "News" sessions and I was very unimpressed - it read like something that Google translate had "written". For example, "For as long time, 1967 to be more exact, I entered the family jewelry business"

I decided to send them an email, mentioning how disappointing that is and how I hoped it was just a hiccough (ahem) since they had only printed their first issue a month ago.

Their charming response:

"Piotr
Trzeba skasowac ten text i dodac inny...
Ten o perlach trzeba poprawic..."

Sorry, nothing in the world would make me subscribe after that. I am irritated to be motivated to spread that little gem around the internet to their potential subscribers.

#### Carotte

• Member
• Posts: 1744
##### Re: "I'm never shopping THERE again!" Share your story!
« Reply #4634 on: September 11, 2013, 06:11:33 AM »
Not every household has an adult in it who neither works nor has no commitments during the day. I would suspect that most homes, actually, don't.

That's what I still find very baffling about our postal system.
I live in an apartment in a two building set up. You have the first set of doors from the street with a digicode (or just a button to press before 8pm) that gets you in a lobby with the mail box for the 2 buildings. right next to that you have the first building (with digicode) and after a small courtward my building, again with digicode. No where do you have a buzzer that lets you call for an apt and there will never be one; ever (buildings are way too old).

Normal course of action is postman gets there, buzz you, brings you your package if you're here or leave a note that he'll try again tomorrow if you're not, the package will only be available in two days at the post office.
Since he'll never be able to buzz (or even want to, poor postman if he has 20 packages and 187 floors to get up to!) and that it's absolutely useless to come by again, why in the ehell doesn't they just leave a note 'come pick it up, available today'?
I don't even know if they bother leaving the postoffice with the packages or not or if they do 'try again' (and do what, stand in the lobby for 10sec and leave?).
And that's the case for roughly 97% of the neighbourhood.

True, I've never went to the local postoffice and asked them if they had it from the first day, because there's a good chance it's not stored there yet.