diff --git a/main.tex b/main.tex index 459a8e4..d7b7d43 100644 --- a/main.tex +++ b/main.tex @@ -5,6 +5,7 @@ \documentclass[aspectratio=169,handout]{beamer} \usefonttheme{professionalfonts} +\usepackage{algo} \usetheme{moloch} % new metropolis % fonts \usepackage{fontspec} @@ -20,6 +21,20 @@ \usepackage{lete-sans-math} \usepackage{booktabs} +\def\etal{\emph{et~al.}} +\def\Real{\mathbb{R}} +\def\Proj{\mathbb{P}} +\def\Hyper{\mathbb{H}} +\def\Integer{\mathbb{Z}} +\def\Natural{\mathbb{N}} +\def\Complex{\mathbb{C}} +\def\Rational{\mathbb{Q}} +\let\N\Natural +\let\Q\Rational +\let\R\Real +\let\Z\Integer +\def\Rd{\Real^d} +\newcommand{\e}{\varepsilon} \title{Connectivity Interdiction \& \\ Perturbed Graphic Matroid Cogirth} \date{\today} @@ -31,23 +46,30 @@ \maketitle \section{Connectivity interdiction} \begin{frame}{Connectivity interdiction} -\textit{What is the maximum change of edge connectivity in a network when some limited set of edges is being removed?} -\pause - -\medskip -\begin{problem}[{[Zenklusen ORL'14]}] -Let $G=(V,E)$ be a graph with edge weights $w:E\to\mathbb{Z}_+$ and edge removal costs $c:E\to\mathbb{Z}_+$ and let $B\in \mathbb Z_+$ be the budget. +\begin{problem}[connectivity interdiction {[Zenklusen ORL'14]}] +Let $G=(V,E)$ be a graph with edge weights $w:E\to\Z_+$ and edge removal costs $c:E\to\Z_+$ and let $B\in \mathbb Z_+$ be the budget. Find $F\subset E$ with $w(F)\leq B$ s.t. the min-cut in $G-F$ is minimized. \end{problem} -\pause -\medskip -connectivity interdiction $\approx$ min-cut + knapsack - -Is there an FPTAS? +\pause\medskip +\begin{problem}[$B$-free min-cut] +Given the same input, define weight function for cuts +\[ w'(\delta(X))=\min_{F\subset \delta(X),c(F)\leq B} w(\delta(X)-F)\] +Find the cut with minimum weight $w'$. +\end{problem} \end{frame} + +\begin{frame}{Applications} +\begin{itemize} +\item drag delivery +\item nuclear smuggling +\item hospital infection control +\item ... +\end{itemize} +\end{frame} + \begin{frame}{Previous works} \begin{table}[h] \centering @@ -55,36 +77,43 @@ Is there an FPTAS? \toprule unit cost $w(\cdot)=1$ & general case & random? & ref \\ \midrule -$O(m^2n^4\log n)$ & $O(m^{2+1/\varepsilon}n^4\log n)$ & $\times$ & [Zenklusen ORL'14] \\ -$O(mn^4\log^2 n)$ & $O(m^{1+1/\varepsilon}n^4\log^2 n)$ & $\checkmark$ & [Zenklusen ORL'14] \\ -$\tilde O(m+n^4 B)$ & $O(\frac{m^2n^4}{\varepsilon}\log(Bnw_{\max}))$ & $\times$ & [C.-C. Huang et al. IPCO'24]\\ -$\tilde O(n^3m\log w_{\max})$ & - & $\checkmark$ & [Drange et al. AAAI'26]\\ -$\tilde O(m^2+n^3B)$ & $\tilde O(m^2+mn^3+\frac{n^3}{\varepsilon})$ & $\times$ & this work\\ -$\tilde O(m+n^3B)$ & $\tilde O(mn^3+\frac{n^3}{\varepsilon})$ & $\checkmark$ & this work\\ +$O(m^2n^4\log n)$ & $O(m^{2+1/\e}n^4\log n)$ & $\times$ & [Zenklusen ORL'14] \\ +$O(mn^4\log^2 n)$ & $O(m^{1+1/\e}n^4\log^2 n)$ & $\checkmark$ & [Zenklusen ORL'14] \\ +$\tilde O(m+n^4 B)$ & $O(\frac{m^2n^4}{\e}\log(Bnw_{\max}))$ & $\times$ & [Huang \etal{} IPCO'24]\\ +$\tilde O(n^3m\log w_{\max})$ & - & $\checkmark$ & [Drange \etal{} AAAI'26]\\ +$\tilde O(m^2+n^3B)$ & $\tilde O(m^2+mn^3+\frac{n^3}{\e})$ & $\times$ & this work\\ +$\tilde O(m+n^3B)$ & $\tilde O(mn^3+\frac{n^3}{\e})$ & $\checkmark$ & this work\\ \bottomrule \end{tabular} \caption{PTASes for connectivity interdiction} \end{table} \end{frame} -\begin{frame}{Method in [C.-C. Huang et al. IPCO'24]} -They use an intemediate problem called \emph{normalized min-cut}. -\begin{problem}[{[Chalermsook ICALP'22]}] -Given the same input as connectivity interdiction, find a cut $C$ and a subset of its edges $F\subset C$ satisfying $0\leq c(F)\leq B$, so that $\frac{w(C-F)}{B-c(F)+1}$ is minimized. +\begin{frame}{Method in [Huang \etal{} IPCO'24]} + +\begin{problem}[\emph{normalized min-cut} {[Chalermsook \etal{} ICALP'22]}] +Given the same input as connectivity interdiction, find +\[\argmin_{\text{cut $C$}, F\subset C} \frac{w(C-F)}{B-c(F)+1} \quad s.t. \quad 0\leq c(F)\leq B.\] \end{problem} \pause\medskip -Normalized min-cut is first considered in [Chalermsook ICALP'22] as a subproblem in MWU framework when solving minimum $k$-edge connected spanning subgraph (ECSS) problem. +First considered in [Chalermsook \etal{} ICALP'22] as a subproblem in MWU framework when solving minimum $k$-edge connected spanning subgraph (ECSS) problem. +\end{frame} -\pause\medskip -... +\begin{frame}{Method in [Huang \etal{} IPCO'24]} +Let $\tau$ be a $(1+\e)$-approximation to the normalized min-cut and let $C^*$ be the optimal $B$-free cut. +\begin{lemma} +$C^*$ is a $(2+2\e)$-approximate min-cut in $(G,w_\tau)$, + +where $w_\tau(e)=\min(\tau c(e),w(e))$ is the truncated edge weight. +\end{lemma} \end{frame} \begin{frame}{LP method} \begin{equation*} \begin{aligned} \min& & \sum_{e} x_e w(e)& & & \\ -s.t.& & \sum_{e\in T} x_e+y_e&\geq 1 & &\forall T\quad \text{($x+y$ is a cut)}\\ +s.t.& & \sum_{e\in T} x_e+y_e&\geq 1 & &\forall \text{spanning tree $T$}\quad \text{($x+y$ is a cut)}\\ & & \sum_{e} y_e c(e) &\leq B & &\text{(budget for $F$)}\\ & & y_e,x_e&\in\{0,1\} & &\forall e \end{aligned}