diff --git a/main.tex b/main.tex index c996366..bedc82b 100644 --- a/main.tex +++ b/main.tex @@ -8,16 +8,7 @@ \usepackage{algo} \usetheme{moloch} % new metropolis % fonts -\usepackage{fontspec} -\setsansfont[ - ItalicFont={Fira Sans Italic}, - BoldFont={Fira Sans Medium}, - BoldItalicFont={Fira Sans Medium Italic} -]{Fira Sans} -\setmonofont[BoldFont={Fira Mono Medium}]{Fira Mono} -\AtBeginEnvironment{tabular}{% - \addfontfeature{Numbers={Monospaced}} -} +\usepackage[defaultsans]{lato} \usepackage{lete-sans-math} \usepackage{soul} \usepackage[dvipsnames]{xcolor} @@ -34,11 +25,11 @@ \newcommand{\propositionautorefname}{Proposition} \newcommand{\problemautorefname}{Problem} \def\etal{\emph{et~al.}} -\def\Real{\mathbb{R}} -\def\Integer{\mathbb{Z}} -\let\R\Real -\let\Z\Integer +\def\R{\mathbb{R}} +\def\Z{\mathbb{Z}} +\def\F{\mathbb{F}} \newcommand{\e}{\varepsilon} +\newcommand{\p}{\pause\medskip} \title{Connectivity Interdiction \& \\ Perturbed Graphic Matroid Cogirth} \date{\today} @@ -56,7 +47,7 @@ Let $G=(V,E)$ be a graph with edge weights $w:E\to\Z_+$ and edge removal costs $ Find $F\subset E$ with $w(F)\leq B$ s.t. the min-cut in $G-F$ is minimized. \end{problem} -\pause\medskip +\p \begin{problem}[$B$-free min-cut] Given the same input, define weight function for cuts \[ w'(\delta(X))=\min_{F\subset \delta(X),c(F)\leq B} w(\delta(X)-F)\] @@ -67,8 +58,8 @@ Find the cut with minimum weight $w'$. \begin{frame}{Applications} \begin{itemize} -\item drag delivery -\item nuclear smuggling +\item drag delivery interdiction +\item nuclear smuggling interdiction \item hospital infection control \item ... \end{itemize} @@ -85,8 +76,8 @@ $O(m^2n^4\log n)$ & $O(m^{2+1/\e}n^4\log n)$ & $\times$ & [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\\ +$\tilde O(m^2+n^3B)$ & $\tilde O(m^2+mn^3+n^3/\e)$ & $\times$ & this work\\ +$\tilde O(m+n^3B)$ & $\tilde O(mn^3+n^3/\e)$ & $\checkmark$ & this work\\ \bottomrule \end{tabular} \caption{PTASes for connectivity interdiction} @@ -100,7 +91,7 @@ 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 +\p 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} @@ -134,7 +125,7 @@ LD=\max_{\lambda \geq 0} \min_{\text{cut $C$ and }F\subset C} w(C-F)-\lambda(B-c We are interested in $L(\lambda)=\min\limits_{\text{cut $C$ and }F\subset C} w(C)-w(F)+\lambda c(F)$. -\pause \medskip +\p Let $C^*$ be the optimal $B$-free mincut and let $\lambda^*$ be the optimal solution to $LD$. \begin{lemma}% \[ L(\lambda^*) \leq w_{\lambda^*}(C^*)<2L(\lambda^*)\] @@ -153,7 +144,7 @@ $\mathcal B$ is the collection of ``bases'' with the following properties: then there exists $b\in B-A$ such that $A-a+b\in \mathcal B$. \end{itemize} -\pause\medskip +\p $X\subset E$ is a cocycle if $X\cap B\neq \emptyset$ holds for all $B\in \mathcal B$. The size of minimum cocycle is the cogirth. @@ -168,7 +159,7 @@ The size of minimum cocycle is the cogirth. \end{itemize} \end{frame} -\begin{frame}{Computing cogirth} +\begin{frame}{Computing (co)girth} \[ \small \begin{array}{ccccccc} @@ -177,12 +168,23 @@ P & & P & & P & & \textcolor{BrickRed}{\text{NP-Hard}} \end{array} \] -\pause\medskip +\p \begin{conjecture}[{[Geelen \etal{} Ann. Comb. 2015]}] -For any proper minor closed class $\mathcal M$ of binary matroids, there is a polynomial time algorithm for computing the girth of matroids in $\mathcal M$. +For any proper minor-closed class $\mathcal M$ of binary matroids, there is a polynomial time algorithm for computing the girth of matroids in $\mathcal M$. \end{conjecture} \end{frame} \begin{frame}{Perturbed graphic matroid} +\begin{theorem}[{[Geelen \etal{} Ann. Comb. 2015]}] +For any proper minor-closed class $\mathcal M$ of binary matroids, there exists two constants $k,t\in \Z_+$ such that, for each vertically $k$-connected matroid $M\in \mathcal M$, there exist matrices $A,P\in \F_2^{r\times n}$ such that $A$ is the incidence matrix of a graph, $\mathrm{rank}(P)\leq t$, and either $M$ or $M^*$ is isomorphic to $M(A+P)$. +\end{theorem} + +\p +\begin{theorem}[{[Geelen \& Kapadia Combinatorica'18]}] +There are polynomial-time randomized algorithm for computing the girth and the cogirth of $M(A+P)$. +\end{theorem} + +\p +Is there a polynomial-time deterministic algorithm ? \end{frame} \end{document} \ No newline at end of file