Questions tagged [weak-convergence]

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For questions about weak convergence, which can concern sequences in normed/ topological vectors spaces, or sequences of measures. Please use other tags like (tag: functional-analysis) or (tag: probability-theory).

2,255 questions
0 votes 1 answer 16 views

Weak continuity vector-valued functions

Let, for each $n\geq 1$, $x_{n}:[0,1]\longrightarrow X$ continuous, where $X$ stands for a banach space, with a norm $\|\cdot\|$. Assume that $X$ is reflexive and $x_{n}([0,1])\subset B(0,r)$ (the ... user avatar user123043
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3 votes 1 answer 26 views

Every contractive self-adjoint operator is the weak limit of projectors

I try to show that every self-adjoint operator $A$ on Hilbert space $H$ with $\|A\| \leq 1$ is the weak limit of the projectors. My teacher told me that the most important part is to show that for one-... user avatar Timur B.
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3 votes 0 answers 36 views

Why is "weak convergence of a sequence to $0$" equivalent to "accumulation points of the sequence are all $0$" in the proof of mean ergodic theorem?

For some context, I am referring to a proof of the Mean Ergodic Theorem from Ergodic Theory and Dynamical Systems by Yves Coudene. Suppose $H$ is a Hilbert space, and let $U \colon H \to H$ be a ... user avatar A. Rodriguez
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2 votes 0 answers 25 views

How to prove $x_n\rightarrow x^*$ if $\{x_n\}$ has a subsequence that converges weakly to $x^*$

Let $X$ be a Banach space and $T\in B(X)$ is a bounded linear operator satisfying that $$ \sup_n\left\|\frac{1}{n}\sum_{k=0}^{n-1}T^k\right\|<\infty,\quad\lim_{n\rightarrow\infty}\frac{1}{n}\|T^n\|=... user avatar Frankie
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2 votes 2 answers 49 views

Convergence in probability implies weak convergence to a Dirac Delta

I am trying to show that, for $c \in \mathbb{R}^d$ constant, if $X_n \rightarrow^{\mathbb{P}} c$, then $\mathbb{P}^{X_n} \Rightarrow \delta_c$, where $X_n:\Omega \rightarrow \mathbb{R}^d$ is a random ... user avatar Anyway142
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3 votes 1 answer 35 views

weak convergence + bounded second moment implies convergence of the moment?

Let $\{\mu_N\}$ be a sequence of random measures which converges almost surely in the weak sense to a deterministic measure $\mu$ with impact support. The weak convergence does not necessarily imply ... user avatar Rostam22
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0 votes 1 answer 26 views

Weak convergence of law of scaled biased random walk

Let $(X_n:n\in\mathbb{N})$ be a sequence of independent, identically distributed random variables of finite mean $m$ and finite variance $\sigma^2$. Set $S_0=0$ and $S_n=X_1+\dots+X_n$ for $n\in\... user avatar verygoodbloke
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2 votes 0 answers 20 views

Uniform integrability of conditional quantile functions

Let $Z^n$ be $\mathbb{R}$-valued random variables which are uniformly integrable, i.e. $$ \lim_{a \to \infty} \sup_{n} E[1_{\{|Z^n| \geq a\}} |Z^n|] = 0. $$ Let $X^n \to N(0,1)$ in distribution, and $... user avatar nien4351
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2 votes 2 answers 85 views

Show that law of sum of sums converges weakly to law integral of brownian motion

Let $(X_k)_{k=1}^\infty$ be a sequence of independent and identically distributed random variables with zero mean and unit variance. Define, for $n\geq1$, $$S_n=\sum_{k=1}^nX_k.$$ Prove that the law ... user avatar verygoodbloke
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2 votes 0 answers 27 views

Find a sequence of functions that converge weakly to 1/2

I'm trying solve the following problem: Find an example of a sequence of functions $f_n:[0,1]\to[0,1]$ such that $$(f_n)_\#\mathscr{L} = \mathscr L$$ but $f_n\rightharpoonup 1/2$ (weak convergence). ... user avatar YLP
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0 votes 2 answers 34 views

Let $X$ be a separable Banach space. Then every pointwise bounded $(f_n) \subset X^*$ has a subsequence that converges uniformly on compact sets

This thread is meant to record a question that I feel interesting during my self-study. I'm very happy to receive your suggestion and comments. See: SE blog: Answer own Question and MSE meta: Answer ... user avatar Akira
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0 votes 1 answer 17 views

Weak convergence imply bounded sequences at all sample points?

Let $(\Omega,\mathcal F, \mathbb P)$ be a probability space, with a sequence of random variables $\{Y_n\}_{n=1}^\infty$ defined on it. Suppose $Y_n\xrightarrow{\ d\ }Y$. Can we say that for (almost) ... user avatar Martund
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0 votes 0 answers 23 views

How to prove that a random variable sequence converges in distribution (weak convergence)?

Given a random variable sequence $X_t$, I wonder how to prove it converges in distribution? For example, if $$X_{t+1}=4+0.5(2r_1-1)(8r_2-X_t)$$ (where $r_1,r_2~i.i.d.\sim U(0,1)$), I can derive the ... user avatar xiaohaozi
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0 votes 0 answers 33 views

Weak convergence against upper invariant measure

Setting I am studying invariant measures and their weak limits. In a book about probability on graphs the following setting is presented in chapter 6.3 (this is a short form of the actual presentation)... user avatar Trumpet
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2 votes 2 answers 59 views

Setwise convergence of measures implies weak convergence under special hypothesis

I'm struggling with producing a proof of the following result: Let $X = \overline{\mathbb{C}}$ be the Riemann sphere, and consider $M(X)$ the space of finite Borel measures on $X$ with norm given by ... user avatar porridgemathematics
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