Jump to content
Main menu
Main menu
move to sidebar
hide
Navigation
Main page
Recent changes
Random page
freem
Search
Search
Appearance
Create account
Log in
Personal tools
Create account
Log in
Pages for logged out editors
learn more
Contributions
Talk
Editing
Openai/6922876a-7988-8007-9c62-5f71772af6aa
(section)
Add languages
Page
Discussion
English
Read
Edit
Edit source
View history
Tools
Tools
move to sidebar
hide
Actions
Read
Edit
Edit source
View history
General
What links here
Related changes
Special pages
Page information
Appearance
move to sidebar
hide
Warning:
You are not logged in. Your IP address will be publicly visible if you make any edits. If you
log in
or
create an account
, your edits will be attributed to your username, along with other benefits.
Anti-spam check. Do
not
fill this in!
==== Below are literal replacements you can paste into your file. ==== ===== Replace Lemma \ref{lem:dyn-W2} by: ===== <syntaxhighlight lang="latex">\begin{lemma}[Displacement $W_2$ control of expectation differences]\label{lem:dyn-W2} Let $P,Q$ be Borel probability measures on $\R$ with finite second moments, and let $T$ be the monotone transport pushing $P$ to $Q$. For $t\in[0,1]$ set $T_t(x)=(1-t)x+tT(x)$ and $X_t=T_t(X)$ with $X\sim P$, and let $P_t$ denote the law of $X_t$. Then, for any $C^1$ function $\varphi$ such that $\int_0^1 \E_{P_t}[\varphi'(X_t)^2]\,dt<\infty$, \[ \left|\E_Q[\varphi]-\E_P[\varphi]\right| \le \left(\int_0^1 \E_{P_t}[\varphi'(X_t)^2]\,dt\right)^{1/2}\, W_2(P,Q). \] \end{lemma} \begin{proof} By the fundamental theorem of calculus and the chain rule, \[ \E_Q[\varphi]-\E_P[\varphi] =\int_0^1 \frac{d}{dt}\E[\varphi(X_t)]\,dt =\int_0^1 \E\big[\varphi'(X_t)\cdot (T(X)-X)\big]\,dt. \] Applying Cauchy--Schwarz in $(t,\Omega)$ gives \[ \left|\E_Q[\varphi]-\E_P[\varphi]\right| \le \Big(\int_0^1 \E[\varphi'(X_t)^2]\,dt\Big)^{1/2} \Big(\int_0^1 \E[(T(X)-X)^2]\,dt\Big)^{1/2}. \] Since $\int_0^1 \E[(T(X)-X)^2]\,dt=\E[(T(X)-X)^2]=W_2(P,Q)^2$, the claim follows. Finally, $\E[\varphi'(X_t)^2]=\E_{P_t}[\varphi'(Z)^2]$ by definition of $P_t$. \end{proof} </syntaxhighlight> ===== Insert after (2.1) defining ψτ\psi_\tauψτ: ===== <syntaxhighlight lang="latex">\medskip\noindent\textbf{Clipped score.} For $B\ge 1$, define the clipped score \[ \tilde\psi_{\tau,B}(u)\ :=\ \mathrm{clip}\big(\psi_\tau(u),\,[-B/\sqrt{\tau},\,B/\sqrt{\tau}]\big), \] and let $\tilde\psi'_{\tau,B}$ be any selection of its (a.e.) derivative; then $\|\tilde\psi_{\tau,B}\|_\infty\le B/\sqrt{\tau}$ and $\|\tilde\psi'_{\tau,B}\|_\infty\le C/\tau$ uniformly in $B$. We henceforth use $\tilde\psi_{\tau_\star,B}$ in the estimating equation \eqref{eq:M-est}, and write $\hat\theta_\ep$ for any solution. The clipping level $B$ is fixed (e.g. $B=10$); on the $W_2$-ball all bounds below are uniform in $B$ and coincide with the unclipped estimator whenever no sample point falls in the extreme tails. </syntaxhighlight> Replace Lemma \ref{lem:score-moments} by the following (stated and proved for the clipped score): <syntaxhighlight lang="latex">\begin{lemma}[Uniform control of clipped score moments]\label{lem:score-moments-clipped} Fix $\tau\in(0,\tfrac12]$ and let $\tilde\psi_\tau:=\tilde\psi_{\tau,B}$ be the clipped score defined above. There exist constants $C_1,C_2,C_3<\infty$ (independent of $B$) such that for all $Q$ with $W_2(Q,\mu_\theta)\le \ep$, \begin{align} \left|\E_Q[\tilde\psi_\tau]-\E_{\nu_{\theta,\tau}}[\tilde\psi_\tau]\right| &\le C_1\,\frac{\ep}{\sqrt{\tau}},\label{eq:bias-score-clipped}\\ \left|\E_Q[\tilde\psi'_\tau]-\E_{\nu_{\theta,\tau}}[\tilde\psi'_\tau]\right| &\le C_2\,\frac{\ep}{\sqrt{\tau}},\label{eq:curv-score-clipped}\\ \left|\E_Q[\tilde\psi_\tau^2]-\E_{\nu_{\theta,\tau}}[\tilde\psi_\tau^2]\right| &\le C_3\,\frac{\ep}{\tau^{3/2}}.\label{eq:var-score-clipped} \end{align} \end{lemma} \begin{proof} Apply Lemma~\ref{lem:dyn-W2} with $P=\nu_{\theta,\tau}$, $\varphi=\tilde\psi_\tau$, $\varphi=\tilde\psi'_\tau$, and $\varphi=\tilde\psi_\tau^2$, respectively. Since $\|\tilde\psi'_\tau\|_\infty\lesssim \tau^{-1}$ and $\|(\tilde\psi_\tau^2)'\|_\infty\lesssim \tau^{-3/2}$, we have \[ \int_0^1 \E_{P_t}[(\tilde\psi'_\tau(X_t-\theta))^2]\,dt \lesssim \tau^{-1},\quad \int_0^1 \E_{P_t}[((\tilde\psi_\tau^2)'(X_t-\theta))^2]\,dt \lesssim \tau^{-3}, \] uniformly over $Q$ with $W_2(Q,\mu_\theta)\le \ep$. The claim follows using $W_2(Q,\nu_{\theta,\tau})\le \ep + W_2(\mu_\theta,\nu_{\theta,\tau})$ and Lemma~\ref{lem:info-W2}. \end{proof} </syntaxhighlight> Adjust the M‑estimation remainder bounds (replace all occurrences of ψ,ψ′,ψ′′\psi,\psi',\psi''ψ,ψ′,ψ′′ by ψ~τ,ψ~τ′\tilde\psi_\tau,\tilde\psi'_\tauψ~τ,ψ~τ′, and remove every use of ∥ψ′′∥∞\|\psi''\|_\infty∥ψ′′∥∞. Where you currently use Lipschitz in ttt via ∥ψ′′∥∞\|\psi''\|_\infty∥ψ′′∥∞, replace it by the uniform bound ∥ψ~τ′∥∞≲τ−1\|\tilde\psi'_\tau\|_\infty\lesssim\tau^{-1}∥ψ~τ′∥∞≲τ−1 and the simple inequality ∣mn(tˉ)−mn(θ)∣≤1n∑i=1n∣ψ~τ′(Xi′−tˉ)−ψ~τ′(Xi′−θ)∣≤∥ψ~τ′∥Lip ∣tˉ−θ∣≲τ−1 ∣tˉ−θ∣.|m_n(\bar t)-m_n(\theta)| \le \frac{1}{n}\sum_{i=1}^n\big|\tilde\psi'_\tau(X_i'-\bar t)-\tilde\psi'_\tau(X_i'-\theta)\big| \le \|\tilde\psi'_\tau\|_\mathrm{Lip}\,|\bar t-\theta| \lesssim \tau^{-1}\,|\bar t-\theta|.∣mn(tˉ)−mn(θ)∣≤n1i=1∑nψ~τ′(Xi′−tˉ)−ψ~τ′(Xi′−θ)≤∥ψ~τ′∥Lip∣tˉ−θ∣≲τ−1∣tˉ−θ∣. Finally, every appearance of \EQ[ψ4]\E_Q[\psi^4]\EQ[ψ4] can be replaced by ∥ψ~τ∥∞4≲τ−2\|\tilde\psi_\tau\|_\infty^4\lesssim \tau^{-2}∥ψ~τ∥∞4≲τ−2, uniformly over the W2W_2W2-ball. ===== If you prefer to avoid clipping, replace \eqref{eq:nu-density} by a globally smoothed bump (e.g. convolution with a compactly supported C∞C^\inftyC∞ kernel κτ\kappa_\tauκτ): ===== <syntaxhighlight lang="latex">\medskip Define $\kappa\in C^\infty_c(\R)$, $\kappa\ge0$, $\int \kappa=1$, and set $\kappa_\tau(x)=\tau^{-1}\kappa(x/\tau)$. Let \[ f(x;\theta,\tau) = \big(\mathbf{1}_{[\theta-\frac12,\ \theta+\frac12]} * \kappa_\tau\big)(x). \] Then $f(\cdot;\theta,\tau)\in C^\infty$, strictly log‑concave, and $\psi_\tau(u)=-\partial_u\log f(u)$ together with its derivatives satisfy $\|\psi_\tau\|_\infty\lesssim \tau^{-1/2}$, $\|\psi_\tau'\|_\infty\lesssim \tau^{-1}$, $\|\psi_\tau''\|_\infty\lesssim \tau^{-3/2}$. All calculations below carry through with the same $\tau$‑scalings \eqref{eq:bias-score}–\eqref{eq:var-score}. </syntaxhighlight> With this modification, Lemma \ref{lem:score-moments} (your original statement) becomes correct; you can keep it as‑is but replace the justification paragraph by the above C∞C^\inftyC∞‐bounds rather than “edge strips” heuristics. ===== Replace the sentence right after \eqref{eq:M-est} by: ===== <syntaxhighlight lang="latex">Let $\hat\theta_\ep$ be any measurable selection from the (nonempty) solution set of \eqref{eq:M-est}. For the globally smoothed model (Remark~\ref{rem:global-smooth}) this solution is unique by strict concavity of the log‑likelihood; for the flat‑top model the solution need not be unique on the event $\max_i X_i'-\min_i X_i'\le 1-2\tau_\star$, in which case we choose the midpoint of the interval of roots. </syntaxhighlight> (If you adopt III.C, add a short Remark saying uniqueness holds a.s. because the log‑likelihood is strictly concave in ttt.) ===== Replace the bias line by: ===== <syntaxhighlight lang="latex">By Lemma~\ref{lem:score-moments-clipped}, $|\E_Q[\psi]|\lesssim \ep/\sqrt{\tau_\star}$ and $m(Q)\asymp I_\star=\pi/\tau_\star$, hence \[ \frac{\E_Q[\psi]^2}{m(Q)^2}\ \lesssim\ \frac{\ep^2/\tau_\star}{(\pi/\tau_\star)^2} \ =\ \frac{\ep^2\,\tau_\star}{\pi^2} \ =\ O\!\big(\ep^{8/3}\big)\quad\text{when } \tau_\star=\ep^{2/3}. \] </syntaxhighlight> (This is strictly smaller than the variance term C/(nI⋆)C/(n I_\star)C/(nI⋆) in the regime where the IDS term dominates.) ===== Replace line in Theorem \ref{thm:IDS-sharp} by: ===== <syntaxhighlight lang="latex">There exists a constant $C<\infty$ such that, for all $n\ge 1$ and $\ep\in(0,\tfrac12]$, </syntaxhighlight> ===== Replace the end of the computation of I(τ)I(\tau)I(τ) by: ===== <syntaxhighlight lang="latex">=\frac{1}{\tau K(0)^2}\int_0^\infty \frac{K'(y)^2}{K(y)}\,dy =\frac{1}{\tau K(0)^2}\int_0^\infty y^2 K(y)\,dy =\frac{1}{\tau K(0)^2}\cdot \frac{1}{2} =\frac{\pi}{\tau}, </syntaxhighlight> and modify the explanatory sentence to: <syntaxhighlight lang="latex">where we used $K(0)=1/\sqrt{2\pi}$ and the Gaussian identity $\int_0^\infty y^2 K(y)\,dy=\tfrac12$. </syntaxhighlight> ===== Replace (A1) by a version that is true under either III.B or III.C: ===== <syntaxhighlight lang="latex">\item[(A1)] The score $\psi$ is continuous, nonincreasing, and piecewise $C^1$ with bounded derivative; in particular $\|\psi\|_\infty<\infty$ and $\|\psi'\|_\infty<\infty$. % (Under the globally smoothed model, $\psi\in C^2$ and $\|\psi''\|_\infty<\infty$ as well.) </syntaxhighlight> If you adopt III.C, you may keep the stronger $C^2$ version and the uses of $|\psi''|\infty$; if you adopt III.B (clipping), simply remove every use of $|\psi''|\infty$ and replace with the Lipschitz bound in ψ′\psi'ψ′ as indicated above.
Summary:
Please note that all contributions to freem are considered to be released under the Creative Commons Attribution-ShareAlike 4.0 (see
Freem:Copyrights
for details). If you do not want your writing to be edited mercilessly and redistributed at will, then do not submit it here.
You are also promising us that you wrote this yourself, or copied it from a public domain or similar free resource.
Do not submit copyrighted work without permission!
Cancel
Editing help
(opens in new window)