{"title":"Red Blue Set Cover problem on axis-parallel hyperplanes and other objects","authors":"V.P. Abidha , Pradeesha Ashok","doi":"10.1016/j.ipl.2024.106485","DOIUrl":"https://doi.org/10.1016/j.ipl.2024.106485","url":null,"abstract":"<div><p>Given a universe <span><math><mi>U</mi><mo>=</mo><mi>R</mi><mo>∪</mo><mi>B</mi></math></span> of a finite set of red elements <em>R</em>, and a finite set of blue elements <em>B</em> and a family <span><math><mi>F</mi></math></span> of subsets of <span><math><mi>U</mi></math></span>, the <span>Red Blue Set Cover</span> problem is to find a subset <span><math><msup><mrow><mi>F</mi></mrow><mrow><mo>′</mo></mrow></msup></math></span> of <span><math><mi>F</mi></math></span> that covers all blue elements of <em>B</em> and minimum number of red elements from <em>R</em>.</p><p>We prove that the <span>Red Blue Set Cover</span> problem is NP-hard even when <em>R</em> and <em>B</em> respectively are sets of red and blue points in <span><math><msup><mrow><mi>IR</mi></mrow><mrow><mn>2</mn></mrow></msup></math></span> and the sets in <span><math><mi>F</mi></math></span> are defined by axis−parallel lines i.e., every set is a maximal set of points with the same <em>x</em> or <em>y</em> coordinate.</p><p>We then study the parameterized complexity of a generalization of this problem, where <span><math><mi>U</mi></math></span> is a set of points in <span><math><msup><mrow><mi>IR</mi></mrow><mrow><mi>d</mi></mrow></msup></math></span> and <span><math><mi>F</mi></math></span> is a collection of set of axis−parallel hyperplanes in <span><math><msup><mrow><mi>IR</mi></mrow><mrow><mi>d</mi></mrow></msup></math></span> under different parameterizations, where <em>d</em> is a constant. For every parameter, we show that the problem is fixed-parameter tractable and also show the existence of a polynomial kernel. We further consider the <span>Red Blue Set Cover</span> problem for some special types of rectangles in <span><math><msup><mrow><mi>IR</mi></mrow><mrow><mn>2</mn></mrow></msup></math></span>.</p></div>","PeriodicalId":56290,"journal":{"name":"Information Processing Letters","volume":"186 ","pages":"Article 106485"},"PeriodicalIF":0.5,"publicationDate":"2024-02-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140042109","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"The group factorization problem in finite groups of Lie type","authors":"Haibo Hong, Shi Bai, Fenghao Liu","doi":"10.1016/j.ipl.2024.106484","DOIUrl":"https://doi.org/10.1016/j.ipl.2024.106484","url":null,"abstract":"<div><p>With the development of Lie theory, Lie groups have profound significance in many branches of mathematics and physics. In Lie theory, matrix exponential plays a crucial role between Lie groups and Lie algebras. Meanwhile, as finite analogues of Lie groups, finite groups of Lie type also have wide application scenarios in mathematics and physics owning to their unique mathematical structures. In this context, it is meaningful to explore the potential applications of finite groups of Lie type in cryptography. In this paper, we firstly built the relationship between matrix exponential and discrete logarithmic problem (DLP) in finite groups of Lie type. Afterwards, we proved that the complexity of solving non-abelian factorization (NAF) problem is polynomial with the rank <em>n</em> of the finite group of Lie type. Furthermore, combining with the Algebraic Span, we proposed an efficient algorithm for solving group factorization problem (GFP) in finite groups of Lie type. Therefore, it's still an open problem to devise secure cryptosystems based on Lie theory.</p></div>","PeriodicalId":56290,"journal":{"name":"Information Processing Letters","volume":"186 ","pages":"Article 106484"},"PeriodicalIF":0.5,"publicationDate":"2024-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140014410","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Regular resolution effectively simulates resolution","authors":"Sam Buss , Emre Yolcu","doi":"10.1016/j.ipl.2024.106489","DOIUrl":"https://doi.org/10.1016/j.ipl.2024.106489","url":null,"abstract":"<div><p>Regular resolution is a refinement of the resolution proof system requiring that no variable be resolved on more than once along any path in the proof. It is known that there exist sequences of formulas that require exponential-size proofs in regular resolution while admitting polynomial-size proofs in resolution. Thus, with respect to the usual notion of simulation, regular resolution is separated from resolution. An alternative, and weaker, notion for comparing proof systems is that of an “effective simulation,” which allows the translation of the formula along with the proof when moving between proof systems. We prove that regular resolution is equivalent to resolution under effective simulations. As a corollary, we recover in a black-box fashion a recent result on the hardness of automating regular resolution.</p></div>","PeriodicalId":56290,"journal":{"name":"Information Processing Letters","volume":"186 ","pages":"Article 106489"},"PeriodicalIF":0.5,"publicationDate":"2024-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S002001902400019X/pdfft?md5=1f40e48e2aad478df5d57137e39d2869&pid=1-s2.0-S002001902400019X-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140030944","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Learning-augmented maximum flow","authors":"Adam Polak , Maksym Zub","doi":"10.1016/j.ipl.2024.106487","DOIUrl":"https://doi.org/10.1016/j.ipl.2024.106487","url":null,"abstract":"<div><p>We propose a framework for speeding up maximum flow computation by using predictions. A prediction is a flow, i.e., an assignment of non-negative flow values to edges, which satisfies the flow conservation property, but does not necessarily respect the edge capacities of the actual instance (since these were unknown at the time of learning). We present an algorithm that, given an <em>m</em>-edge flow network and a predicted flow, computes a maximum flow in <span><math><mi>O</mi><mo>(</mo><mi>m</mi><mi>η</mi><mo>)</mo></math></span> time, where <em>η</em> is the <span><math><msub><mrow><mi>ℓ</mi></mrow><mrow><mn>1</mn></mrow></msub></math></span> error of the prediction, i.e., the sum over the edges of the absolute difference between the predicted and optimal flow values. Moreover, we prove that, given an oracle access to a distribution over flow networks, it is possible to efficiently PAC-learn a prediction minimizing the expected <span><math><msub><mrow><mi>ℓ</mi></mrow><mrow><mn>1</mn></mrow></msub></math></span> error over that distribution. Our results fit into the recent line of research on learning-augmented algorithms, which aims to improve over worst-case bounds of classical algorithms by using predictions, e.g., machine-learned from previous similar instances. So far, the main focus in this area was on improving competitive ratios for online problems. Following Dinitz et al. (2021) <span>[6]</span>, our results are among the firsts to improve the running time of an offline problem.</p></div>","PeriodicalId":56290,"journal":{"name":"Information Processing Letters","volume":"186 ","pages":"Article 106487"},"PeriodicalIF":0.5,"publicationDate":"2024-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140030945","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Prenex universal first-order safety properties","authors":"Besik Dundua , Ioane Kapanadze , Helmut Seidl","doi":"10.1016/j.ipl.2024.106488","DOIUrl":"https://doi.org/10.1016/j.ipl.2024.106488","url":null,"abstract":"<div><p>We show that every prenex universal syntactic first-order safety property can be compiled into a universal invariant of a first-order transition system using quantifier-free substitutions only. We apply this insight to prove that every such safety property is decidable for first-order transition systems with stratified guarded updates only.</p></div>","PeriodicalId":56290,"journal":{"name":"Information Processing Letters","volume":"186 ","pages":"Article 106488"},"PeriodicalIF":0.5,"publicationDate":"2024-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0020019024000188/pdfft?md5=4b718d782f26b6bc7eb47445f9e59272&pid=1-s2.0-S0020019024000188-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140024064","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Tight inapproximability of Nash equilibria in public goods games","authors":"Jérémi Do Dinh , Alexandros Hollender","doi":"10.1016/j.ipl.2024.106486","DOIUrl":"https://doi.org/10.1016/j.ipl.2024.106486","url":null,"abstract":"<div><p>We study public goods games, a type of game where every player has to decide whether or not to produce a good which is <em>public</em>, i.e., neighboring players can also benefit from it. Specifically, we consider a setting where the good is indivisible and where the neighborhood structure is represented by a directed graph, with the players being the nodes. Papadimitriou and Peng (2023) recently showed that in this setting computing mixed Nash equilibria is <span>PPAD</span>-hard, and that this remains the case even for <em>ε</em>-well-supported approximate equilibria for some sufficiently small constant <em>ε</em>. In this work, we strengthen this inapproximability result by showing that the problem remains <span>PPAD</span>-hard for any non-trivial approximation parameter <em>ε</em>.</p></div>","PeriodicalId":56290,"journal":{"name":"Information Processing Letters","volume":"186 ","pages":"Article 106486"},"PeriodicalIF":0.5,"publicationDate":"2024-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0020019024000164/pdfft?md5=4401d2c9ad85ff27d95ed156a73d6f7a&pid=1-s2.0-S0020019024000164-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139993181","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Recognizing LBFS trees of bipartite graphs","authors":"Robert Scheffler","doi":"10.1016/j.ipl.2024.106483","DOIUrl":"https://doi.org/10.1016/j.ipl.2024.106483","url":null,"abstract":"<div><p>The graph searches Breadth First Search (BFS) and Depth First Search (DFS) and the spanning trees constructed by them are some of the most basic concepts in algorithmic graph theory. BFS trees are first-in trees, i.e., every vertex is connected to its first visited neighbor. DFS trees are last-in trees, i.e., every vertex is connected to the last visited neighbor before it. The problem whether a given spanning tree can be the first-in tree or last-in tree of a graph search ordering was introduced in the 1980s and has been studied for several graph searches and graph classes. Here, we consider the problem of deciding whether a given spanning tree of a bipartite graph can be a first-in tree or a last-in tree of the Lexicographic Breadth First Search (LBFS), a special variant of BFS that is commonly used in graph algorithms. We show that the recognition of both first-in trees and last-in trees of LBFS is <span><math><mi>NP</mi></math></span>-hard even if the start vertex of the search ordering is fixed and the height of the tree is four. We prove that the bound on the height is tight (unless <span><math><mi>P</mi><mo>=</mo><mrow><mi>NP</mi></mrow></math></span>) by showing that for all spanning trees of bipartite graphs with height smaller than four we can solve both search tree recognition problems of LBFS in polynomial time. Finally, we give a linear-time algorithm that solves both problems for chordal bipartite graphs and fixed start vertices.</p></div>","PeriodicalId":56290,"journal":{"name":"Information Processing Letters","volume":"186 ","pages":"Article 106483"},"PeriodicalIF":0.5,"publicationDate":"2024-02-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0020019024000139/pdfft?md5=0a705320becd861a4100ad392710d19e&pid=1-s2.0-S0020019024000139-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139738315","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Skolem and positivity completeness of ergodic Markov chains","authors":"Mihir Vahanwala","doi":"10.1016/j.ipl.2024.106481","DOIUrl":"https://doi.org/10.1016/j.ipl.2024.106481","url":null,"abstract":"<div><p>We consider the following Markov Reachability decision problems that view Markov Chains as Linear Dynamical Systems: given a finite, rational Markov Chain, source and target states, and a rational threshold, does the probability of reaching the target from the source at the <span><math><msup><mrow><mi>n</mi></mrow><mrow><mi>t</mi><mi>h</mi></mrow></msup></math></span> step: (i) equal the threshold for some <em>n</em>? (ii) cross the threshold for some <em>n</em>? (iii) cross the threshold for infinitely many <em>n</em>? These problems are respectively known to be equivalent to the Skolem, Positivity, and Ultimate Positivity problems for Linear Recurrence Sequences (LRS), number-theoretic problems whose decidability has been open for decades. We present an elementary reduction from LRS Problems to Markov Reachability Problems that improves the state of the art as follows. (a) We map LRS to <em>ergodic</em> (irreducible and aperiodic) Markov Chains that are ubiquitous, not least by virtue of their spectral structure, and (b) our reduction maps LRS of order <em>k</em> to Markov Chains of order <span><math><mi>k</mi><mo>+</mo><mn>1</mn></math></span>: a substantial improvement over the previous reduction that mapped LRS of order <em>k</em> to reducible and periodic Markov chains of order <span><math><mn>4</mn><mi>k</mi><mo>+</mo><mn>5</mn></math></span>. This contribution is significant in view of the fact that the number-theoretic hardness of verifying Linear Dynamical Systems can often be mitigated by spectral assumptions and restrictions on order.</p></div>","PeriodicalId":56290,"journal":{"name":"Information Processing Letters","volume":"186 ","pages":"Article 106481"},"PeriodicalIF":0.5,"publicationDate":"2024-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0020019024000115/pdfft?md5=da39be99a4cd399e31f45e5c0e089132&pid=1-s2.0-S0020019024000115-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139738314","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"On size-independent sample complexity of ReLU networks","authors":"Mark Sellke","doi":"10.1016/j.ipl.2024.106482","DOIUrl":"https://doi.org/10.1016/j.ipl.2024.106482","url":null,"abstract":"<div><p>We study the sample complexity of learning ReLU neural networks from the point of view of generalization. Given norm constraints on the weight matrices, a common approach is to estimate the Rademacher complexity of the associated function class. Previously <span>[9]</span> obtained a bound independent of the network size (scaling with a product of Frobenius norms) except for a factor of the square-root depth. We give a refinement which often has no explicit depth-dependence at all.</p></div>","PeriodicalId":56290,"journal":{"name":"Information Processing Letters","volume":"186 ","pages":"Article 106482"},"PeriodicalIF":0.5,"publicationDate":"2024-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139907353","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Expressive completeness by separation for discrete time interval temporal logic with expanding modalities","authors":"Dimitar P. Guelev , Ben Moszkowski","doi":"10.1016/j.ipl.2024.106480","DOIUrl":"10.1016/j.ipl.2024.106480","url":null,"abstract":"<div><p>Recently we established an analog of Gabbay's separation theorem about linear temporal logic (LTL) for the extension of Moszkowski's discrete time propositional Interval Temporal Logic (ITL) by two sets of expanding modalities, namely the unary neighbourhood modalities and the binary weak inverses of ITL's <em>chop</em> operator. One of the many useful applications of separation in LTL is the concise proof of LTL's expressive completeness wrt the monadic first-order theory of <span><math><mo>〈</mo><mi>ω</mi><mo>,</mo><mo><</mo><mo>〉</mo></math></span> it enables. In this paper we show how our separation theorem about ITL facilitates a similar proof of the expressive completeness of ITL with expanding modalities wrt the monadic first- and second-order theories of <span><math><mo>〈</mo><mi>Z</mi><mo>,</mo><mo><</mo><mo>〉</mo></math></span>.</p></div>","PeriodicalId":56290,"journal":{"name":"Information Processing Letters","volume":"186 ","pages":"Article 106480"},"PeriodicalIF":0.5,"publicationDate":"2024-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0020019024000103/pdfft?md5=587945e657c3449e305fda69d4d98cbd&pid=1-s2.0-S0020019024000103-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139690178","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}