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- research-articleNovember 2023
Polynomial Upper Bounds on the Number of Differing Columns of Δ-Modular Integer Programs
Mathematics of Operations Research (MOOR), Volume 48, Issue 4Pages 2267–2286https://doi.org/10.1287/moor.2022.1339We study integer-valued matrices with bounded determinants. Such matrices appear in the theory of integer programs (IPs) with bounded determinants. For example, an IP can be solved in strongly polynomial time if the constraint matrix is bimodular: that is,...
- research-articleNovember 2023
Recognizing Series-Parallel Matrices in Linear Time
INFORMS Journal on Computing (INFORMS-IJOC), Volume 35, Issue 6Pages 1404–1418https://doi.org/10.1287/ijoc.2021.0233A series-parallel matrix is a binary matrix that can be obtained from an empty matrix by successively adjoining rows or columns that are copies of an existing row/column or have at most one one-entry. Equivalently, series-parallel matrices are ...
- research-articleJune 2023
Fast Algorithms via Dynamic-Oracle Matroids
STOC 2023: Proceedings of the 55th Annual ACM Symposium on Theory of ComputingPages 1229–1242https://doi.org/10.1145/3564246.3585219We initiate the study of matroid problems in a new oracle model called dynamic oracle. Our algorithms in this model lead to new bounds for some classic problems, and a “unified” algorithm whose performance matches previous results developed in various ...
- research-articleSeptember 2022
An Optimal Approximation for Submodular Maximization Under a Matroid Constraint in the Adaptive Complexity Model
An Exponentially Faster Algorithm for Submodular Maximization Under a Matroid Constraint
This paper studies the problem of submodular maximization under a matroid constraint. It is known since the 1970s that the greedy algorithm obtains a constant-factor ...
In this paper, we study submodular maximization under a matroid constraint in the adaptive complexity model. This model was recently introduced in the context of submodular optimization to quantify the information theoretic complexity of black-box ...
- research-articleJanuary 2022
Small Cocircuits in Minimally Vertically 4-Connected Matroids
SIAM Journal on Discrete Mathematics (SIDMA), Volume 36, Issue 4Pages 2822–2829https://doi.org/10.1137/21M1454869Halin proved that every minimally $k$-connected graph has a vertex of degree $k$. More generally, does every minimally vertically $k$-connected matroid have a $k$-element cocircuit? Results of Murty and Wong give an affirmative answer when $k \le 3$. We ...
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- research-articleJanuary 2022
The 9-Connected Excluded Minors for the Class of Quasi-graphic Matroids
SIAM Journal on Discrete Mathematics (SIDMA), Volume 36, Issue 3Pages 1627–1644https://doi.org/10.1137/21M142784XThe class of quasi-graphic matroids, recently introduced by Geelen, Gerards, and Whittle, is minor closed and contains both the class of lifted-graphic matroids and the class of frame matroids, each of which generalizes the class of graphic matroids. In ...
- research-articleJanuary 2022
Matrices of Optimal Tree-Depth and a Row-Invariant Parameterized Algorithm for Integer Programming
SIAM Journal on Computing (SICOMP), Volume 51, Issue 3Pages 664–700https://doi.org/10.1137/20M1353502A long line of research on fixed parameter tractability of integer programming culminated with showing that integer programs with $n$ variables and a constraint matrix with dual tree-depth $d$ and largest entry $\Delta$ are solvable in time $g(d,\Delta){...
- research-articleJanuary 2022
The Structure of $I_4$-Free and Triangle-Free Binary Matroids
SIAM Journal on Discrete Mathematics (SIDMA), Volume 36, Issue 3Pages 1711–1729https://doi.org/10.1137/20M1343099A simple binary matroid is called $I_4$-free if none of its rank-4 flats are independent sets. These objects can be equivalently defined as the sets $E$ of points in $\mbox{PG}(n-1,2)$ for which $E \cap F$ is not a basis of $F$ for any four-dimensional ...
- research-articleMay 2021
Strong Algorithms for the Ordinal Matroid Secretary Problem
Mathematics of Operations Research (MOOR), Volume 46, Issue 2Pages 642–673https://doi.org/10.1287/moor.2020.1083In the ordinal matroid secretary problem (MSP), candidates do not reveal numerical weights, but the decision maker can still discern if a candidate is better than another. An algorithm α is probability-competitive if every element from the optimum appears ...
- research-articleFebruary 2021
Efficient Black-Box Reductions for Separable Cost Sharing
Mathematics of Operations Research (MOOR), Volume 46, Issue 1Pages 134–158https://doi.org/10.1287/moor.2020.1050In cost-sharing games with delays, a set of agents jointly uses a subset of resources. Each resource has a fixed cost that has to be shared by the players, and each agent has a nonshareable player-specific delay for each resource. A separable cost-sharing ...
- research-articleJanuary 2021
List Coloring of Two Matroids through Reduction to Partition Matroids
SIAM Journal on Discrete Mathematics (SIDMA), Volume 35, Issue 3Pages 2192–2209https://doi.org/10.1137/20M1385615In the list coloring problem for two matroids, we are given matroids $M_1=(S,{\mathcal{I}}_1)$ and $M_2=(S,{\mathcal{I}}_2)$ on the same ground set $S$, and the goal is to determine the smallest number $k$ such that, given arbitrary lists $L_s$ of $k$ ...
- research-articleJanuary 2021
Online Contention Resolution Schemes with Applications to Bayesian Selection Problems
SIAM Journal on Computing (SICOMP), Volume 50, Issue 2Pages 255–300https://doi.org/10.1137/18M1226130We introduce a new rounding technique designed for online optimization problems, which is related to contention resolution schemes, a technique initially introduced in the context of submodular function maximization. Our rounding technique, which we call ...
- research-articleAugust 2020
A General Coreset-Based Approach to Diversity Maximization under Matroid Constraints
ACM Transactions on Knowledge Discovery from Data (TKDD), Volume 14, Issue 5Article No.: 60, Pages 1–27https://doi.org/10.1145/3402448Diversity maximization is a fundamental problem in web search and data mining. For a given dataset S of n elements, the problem requires to determine a subset of S containing k≪n “representatives” which maximize some diversity function expressed in ...
- research-articleJune 2020
Representative Sets and Irrelevant Vertices: New Tools for Kernelization
Journal of the ACM (JACM), Volume 67, Issue 3Article No.: 16, Pages 1–50https://doi.org/10.1145/3390887We continue the development of matroid-based techniques for kernelization, initiated by the present authors [47]. We significantly extend the usefulness of matroid theory in kernelization by showing applications of a result on representative sets due to ...
- research-articleMay 2020
Demystifying Emergent Intelligence and Its Effect on Performance In Large Robot Swarms
AAMAS '20: Proceedings of the 19th International Conference on Autonomous Agents and MultiAgent SystemsPages 474–482We investigate the emergence of swarm intelligence using task allocation in large robot swarms. First, we compare task decomposition graphs of different levels of richness and measure the emergent intelligence arising from self-organized task allocation ...
- research-articleJanuary 2020
Subdeterminant Maximization via Nonconvex Relaxations and Anti-Concentration
SIAM Journal on Computing (SICOMP), Volume 49, Issue 6Pages 1249–1270https://doi.org/10.1137/19M1309523Several fundamental problems that arise in optimization and computer science can be cast as follows: Given vectors $v_1,\ldots,v_m \in \mathbb{R}^d$ and a constraint family $\mathcal{B} \subseteq 2^{[m]}$, find a set $S \in \mathcal{B}$ that maximizes the ...
- research-articleJanuary 2020
L-Infinity Optimization to Bergman Fans of Matroids with an Application to Phylogenetics
SIAM Journal on Discrete Mathematics (SIDMA), Volume 34, Issue 1Pages 701–720https://doi.org/10.1137/18M1218741Given a dissimilarity map $\delta$ on a finite set $X$, the set of ultrametrics (equidistant tree metrics) which are $l^\infty$-nearest to $\delta$ is a tropical polytope. We give an internal description of this tropical polytope which we use to derive a ...
- research-articleJanuary 2020
The Matroid Secretary Problem for Minor-Closed Classes and Random Matroids
SIAM Journal on Discrete Mathematics (SIDMA), Volume 34, Issue 1Pages 163–176https://doi.org/10.1137/16M1107899We prove that for every proper minor-closed class $\mathcal{M}$ of $\mathbb{F}_p$-representable matroids, there exists an $O(1)$-competitive algorithm for the matroid secretary problem on $\mathcal{M}$. This result relies on the extremely powerful ...
- research-articleJune 2019
Parallelizing greedy for submodular set function maximization in matroids and beyond
STOC 2019: Proceedings of the 51st Annual ACM SIGACT Symposium on Theory of ComputingPages 78–89https://doi.org/10.1145/3313276.3316406We consider parallel, or low adaptivity, algorithms for submodular function maximization. This line of work was recently initiated by Balkanski and Singer and has already led to several interesting results on the cardinality constraint and explicit ...
- research-articleJune 2019
An optimal approximation for submodular maximization under a matroid constraint in the adaptive complexity model
STOC 2019: Proceedings of the 51st Annual ACM SIGACT Symposium on Theory of ComputingPages 66–77https://doi.org/10.1145/3313276.3316304In this paper we study submodular maximization under a matroid constraint in the adaptive complexity model. This model was recently introduced in the context of submodular optimization to quantify the information theoretic complexity of black-box ...