A blocking set in a graph G is a subset of vertices that intersects every maximum independent set of G. Let mmbs(G) be the size of a maximum (inclusion-wise) minimal blocking set of G. This parameter has recently play...
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A blocking set in a graph G is a subset of vertices that intersects every maximum independent set of G. Let mmbs(G) be the size of a maximum (inclusion-wise) minimal blocking set of G. This parameter has recently played an important role in the kernelization of VERTEX COVER with structural parameterizations. We provide a panorama of the complexity of computing mmbs parameterized by the natural parameter and the independence number of the input graph. We also consider the closely related parameter mmhs, which is the size of a maximum minimal hitting set of a hypergraph. Finally, we consider the problem of computing mmbs parameterized by treewidth, especially relevant in the context of kernelization. Since a blocking set intersects every maximum-sized independent set of a given graph and properties involving counting the sizes of arbitrarily large sets are typically non-expressible in monadic second-order logic, its tractability does not seem to follow from Courcelle's theorem. Our main technical contribution is a fixed-parameter tractable algorithm for this problem.
Hubs are high-degree nodes within a network, ubiquitous in complex networks such as telecommunication, biological, social and semantic networks. Here, we do not seek a hub that is a single node, but a hub consisting o...
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Hubs are high-degree nodes within a network, ubiquitous in complex networks such as telecommunication, biological, social and semantic networks. Here, we do not seek a hub that is a single node, but a hub consisting of k nodes. Formally, given a graph G = (V, E), we a seek a set A subset of V of size k that induces a connected subgraph from which at least p edges emanate. Thus, we identify k nodes which can act as a unit (due to the connectivity constraint) that is a hub (due to the cut constraint). This problem, which we call MULTI-NODE HUB (MNH), is a variant of the classic MAX CUT problem. While it is easy to see that MNH is W[1]-hard with respect to the parameter k, our main contribution is a parameterized algorithm that shows that MNH is FPT with respect to the parameter p. (C) 2022 Elsevier Inc. All rights reserved.
Consider a graph G where each vertex has a threshold. A vertex v in G is activated if the number of active vertices adjacent to v is at least as many as its threshold. A vertex subset A(0) of G is a target set if even...
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ISBN:
(纸本)9789819723393;9789819723409
Consider a graph G where each vertex has a threshold. A vertex v in G is activated if the number of active vertices adjacent to v is at least as many as its threshold. A vertex subset A(0) of G is a target set if eventually all vertices in G are activated by initially activating vertices of A(0). The Target Set Selection problem (TSS) involves finding the smallest target set of G with vertex thresholds. This problem has already been extensively studied and is known to be NP-hard even for very restricted conditions. In this paper, we analyze TSS and its weighted variant, called the Weighted Target Set Selection problem (WTSS) from the perspective of parameterized complexity. Let k be the solution size and l be the maximum threshold. We first show that TSS is W[1]-hard for split graphs when parameterized by k + l, and W[2]-hard for cographs when parameterized by k. We also prove that WTSS is W[2]-hard for trivially perfect graphs when parameterized by k. On the other hand, we show that WTSS can be solved in O(n log n) time for complete graphs. Additionally, we design FPT algorithms for WTSS when parameterized by nd + l, tw + l, ce, and vc, where nd is the neighborhood diversity, tw is the treewidth, ce is the cluster editing number, and VC is the vertex cover number of the input graph.
We initiate the parameterized complexity study of minimum t-spanner problems on directed graphs. For a positive integer t, a multiplicative t-spanner of a (directed) graph G is a spanning subgraph H such that the dist...
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We initiate the parameterized complexity study of minimum t-spanner problems on directed graphs. For a positive integer t, a multiplicative t-spanner of a (directed) graph G is a spanning subgraph H such that the distance between any two vertices in H is at most t times the distance between these vertices in G, that is, H keeps the distances in G up to the distortion (or stretch) factor t. An additive t-spanner is defined as a spanning subgraph that keeps the distances up to the additive distortion parameter t, that is, the distances in H and G differ by at most t. The task of Directed Multiplicative Spanner is, given a directed graph G with m arcs and positive integers t and k, decide whether G has amultiplicative t-spanner with at most m-k arcs. Similarly, Directed Additive Spanner asks whether G has an additive t-spanner with at most m-k arcs. We show that (i) Directed Multiplicative Spanner admits a polynomial kernel of size O(k(4)t(5)) and can be solved in randomized (4t)(k) . n(O(1)) time, (ii) the weighted variant of DIRECTED MULTIPLICATIVE SPANNER can be solved in k(2k) . n(O(1)) time on directed acyclic graphs, (iii) Directed Additive Spanner is W[1]-hard when parameterized by k for every fixed t >= 1 evenwhen the input graphs are restricted to be directed acyclic graphs. The latter claim contrasts with the recent result of Kobayashi from STACS 2020 that the problem for undirected graphs is FPT when parameterized by t and k.
We consider GROUP CONTROL BY ADDING INDIVIDUALS(GCAI)in the setting of group identification for two procedural rules-the consensus-start-respecting rule and the liberal-start-respecting *** is known that GCAI for both...
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We consider GROUP CONTROL BY ADDING INDIVIDUALS(GCAI)in the setting of group identification for two procedural rules-the consensus-start-respecting rule and the liberal-start-respecting *** is known that GCAI for both rules are NP-hard,but whether they are fixed-parameter tractable with respect to the number of distinguished individuals remained *** resolve both open problems in the *** addition,we strengthen the NP-hardness of GCAI by showing that,with respect to the natural parameter the number of added individuals,GCAI for both rules are W[2]-***,the W[2]-hardness for the liberal-startrespecting rule holds even when restricted to a very special case where the qualifications of individuals satisfy the so-called consecutive ones ***,for the consensus-startrespecting rule,the problem becomes polynomial-time solvable in this special *** also study a dual restriction where the disqualifications of individuals fulfill the consecutive ones property,and show that under this restriction GCAI for both rules turn out to be polynomial-time *** reductions for showing W[2]-hardness also imply several algorithmic lowerbounds.
Given an undirected graph G, we study the SATISFACTORY PARTITION problem, where the goal is to decide whether it is possible to partition the vertex set of G into two parts such that each vertex has at least as many n...
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Given an undirected graph G, we study the SATISFACTORY PARTITION problem, where the goal is to decide whether it is possible to partition the vertex set of G into two parts such that each vertex has at least as many neighbours in its own part as in the other part. The BALANCED SATISFACTORY PARTITION problem is a variant of the above problem where the two partite sets are required to have the same cardinality. Both problems are known to be NP-complete. This problem was introduced by Gerber and Kobler (2000) [9] and further studied by other authors, but its parameterized complexity remains open until now. We enhance our understanding of the problem from the viewpoint of parameterized complexity. The main results of the paper are the following: (1) SATISFACTORY PARTITION is polynomial-time solvable for block graphs, (2) SATISFACTORY PARTITION and BALANCED SATISFACTORY PARTITION are fixed parameter tractable (FPT) when parameterized by neighbourhood diversity. (3) SATISFACTORY PARTITION and its balanced version can be solved in polynomial time for graphs of bounded clique-width, and (4) BALANCED SATISFACTORY PARTITION is W[1]-hard when parameterized by treewidth. (C) 2022 Elsevier B.V. All rights reserved.
A 2-interval is the union of two disjoint intervals on the real line. Two 2-intervals D1 and D2 are disjoint if their intersection is empty (i.e., no interval of D1 intersects any interval of D2). There can be three d...
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A 2-interval is the union of two disjoint intervals on the real line. Two 2-intervals D1 and D2 are disjoint if their intersection is empty (i.e., no interval of D1 intersects any interval of D2). There can be three different relations between two disjoint 2-intervals;namely, preceding (<), nested (E) and crossing (0). Two 2-intervals D1 and D2 are called R-comparable for some R is an element of {<, E, 0}, if either D1R D2 or D2R D1. A set D of disjoint 2intervals is R-comparable, for some R subset of {<, E, 0} and R = empty set , if every pair of 2-intervals in D are R-comparable for some R is an element of R. Given a set of 2-intervals and some R subset of {<, E, 0}, the objective of the 2-interval pattern problem is to find a largest subset of 2-intervals that is R-comparable. The 2-interval pattern problem is known to be W[1]-hard when |R| = 3 and NP-hard when |R| = 2 (except for R = {<, E}, which is solvable in quadratic time). In this paper, we fully settle the parameterized complexity of the problem by showing that it is W[1]-hard for both R = {E, 0} and R = {<, 0} (when parameterized by the size of an optimal solution). This answers the open question posed by Vialette ((2008) [22]).
We give a comprehensive account on the parameterized complexity of model checking and satisfiability of propositional inclusion and independence logic. We discover that for most parameterizations the problems are eith...
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ISBN:
(数字)9783031397844
ISBN:
(纸本)9783031397837;9783031397844
We give a comprehensive account on the parameterized complexity of model checking and satisfiability of propositional inclusion and independence logic. We discover that for most parameterizations the problems are either in FPT or paraNP-complete.
GRAPH BURNING asks, given a graph G = (V, E) and an integer k, whether there exists (b(0), ...,b(k-1)) is an element of V-k such that every vertex in G has distance at most i from some b(i). This problem is known to b...
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GRAPH BURNING asks, given a graph G = (V, E) and an integer k, whether there exists (b(0), ...,b(k-1)) is an element of V-k such that every vertex in G has distance at most i from some b(i). This problem is known to be NP-complete even on connected caterpillars of maximum degree 3. We study the parameterized complexity of this problem and answer all questions by Kare and Reddy [IWOCA 2019] about the parameterized complexity of the problem. We show that the problem is W[2]-complete parameterized by k and that it does not admit a polynomial kernel parameterized by vertex cover number unless NP subset of coNP/poly. We also show that the problem is fixed-parameter tractable parameterized by clique-width plus the maximum diameter among all connected components. This implies the fixed-parameter tractability parameterized by modular-width, by treedepth, and by distance to cographs. Using a different technique, we show that parameterization by distance to split graphs is also tractable. We finally show that the problem parameterized by max leaf number is XP.
In the binary networked public goods (BNPG for short) game, every player needs to decide if she participates in a public project whose utility is shared equally by the community. We study the problem of deciding if th...
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In the binary networked public goods (BNPG for short) game, every player needs to decide if she participates in a public project whose utility is shared equally by the community. We study the problem of deciding if there exists a pure strategy Nash equilibrium (PSNE) in such games. The problem is already known to be NP-complete. This casts doubt on predictive power of PSNE in BNPG games. We provide fine-grained analysis of this problem under the lens of parameterized complexity theory. We consider various natural graph parameters and show W[1]-hardness, XP, and FPT results. Hence, our work significantly improves our understanding of BNPG games where PSNE serves as a reliable solution concept. We finally prove that some graph classes, for example path, cycle, bi-clique, and complete graph, always have a PSNE if the utility function of the players are same.
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