In this paper, we investigate the parameterized complexity of model checking for Dependence and Independence logic, which are well studied logics in the area of Team Semantics. We start with a list of nine immediate p...
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In this paper, we investigate the parameterized complexity of model checking for Dependence and Independence logic, which are well studied logics in the area of Team Semantics. We start with a list of nine immediate parameterizations for this problem, namely the number of disjunctions (i.e. splits)/(free) variables/universal quantifiers, formula-size, the tree-width of the Gaifman graph of the input structure, the size of the universe/team and the arity of dependence atoms. We present a comprehensive picture of the parameterized complexity of model checking and obtain a division of the problem into tractable and various intractable degrees. Furthermore, we also consider the complexity of the most important variants (data and expression complexity) of the model checking problem by fixing parts of the input.
We study the complexity of graph modification problems with respect to homomorphism-based colouring properties of edge-coloured graphs. A homomorphism from an edge-coloured graph G to an edge-coloured graph H is a ver...
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We study the complexity of graph modification problems with respect to homomorphism-based colouring properties of edge-coloured graphs. A homomorphism from an edge-coloured graph G to an edge-coloured graph H is a vertex-mapping from G to H that preserves adjacencies and edge-colours. We consider the property of having a homomorphism to a fixed edge-coloured graph H, which generalises the classic vertex-colourability property. The question we are interested in is the following: given an edge-coloured graph G, can we perform k graph operations so that the resulting graph admits a homomorphism to H? The operations we consider are vertex-deletion, edge-deletion and switching (an operation that permutes the colours of the edges incident to a given vertex). Switching plays an important role in the theory of signed graphs, that are 2-edge-coloured graphs whose colours are the signs + and -. We denote the corresponding problems (parameterized by k) by VD-H- COLOURING, ED-H-COLOURING and SW-H-COLOURING. These problems generalise the extensively studied H-COLOURING problem (where one has to decide if an input graph admits a homomorphism to a fixed target H). For 2-edge-coloured H, it is known that H-COLOURING already captures the complexity of all fixed-target Constraint Satisfaction Problems. Our main focus is on the case where H is an edge-coloured graph with at most two vertices, a case that is already interesting since it includes standard problems such as VERTEX COVER, ODD CYCLE TRANSVERSAL and EDGE BIPARTIZATION. For such a graph H, we give a P/NP-complete complexity dichotomy for all three VD-H-COLOURING, ED-H-COLOURING and SW-H-COLOURING problems. Then, we address their parameterized complexity. We show that all VD-H-COLOURING and ED-H-COLOURING problems for such H are FPT. This is in contrast with the fact that already for some H of order 3, unless P = NP, none of the three considered problems is in XP, since 3- COLOURING is NP-complete. We show that the situation i
The traveling purchaser problem (TPP), a generalization of the traveling salesman problem, is to determine a tour of suppliers and purchase needed products from suppliers while minimizing the traveling and purchasing ...
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The traveling purchaser problem (TPP), a generalization of the traveling salesman problem, is to determine a tour of suppliers and purchase needed products from suppliers while minimizing the traveling and purchasing cost. This problem finds applications in the routing and scheduling contexts and its variants with different constraints have been widely studied. Motivated by the phenomenon that most real-world instances of TPP have a small parameter (such as the number of suppliers, the number of products to purchase, and others), we study TPP and its variants from the view of parameterized complexity. We show that TPP and some variants are fixed-parameter tractable by taking the numberkof products or the numbermof suppliers as the parameter, and W[2]-hard by taking the numberqof visited suppliers as the parameter. Furthermore, we implement some of our fixed-parameter tractable algorithms to show that they are practically effective when the parameters are not very large.
In this paper, we investigate the parameterized complexity of d-restricted tau-synthesis (dR tau S) parameterized by d for a range of Boolean types of nets tau. We show that dR tau S is W[1]-hard for 64 of 128 possibl...
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ISBN:
(纸本)9783030592660;9783030592677
In this paper, we investigate the parameterized complexity of d-restricted tau-synthesis (dR tau S) parameterized by d for a range of Boolean types of nets tau. We show that dR tau S is W[1]-hard for 64 of 128 possible Boolean types that allow places and transitions to be independent.
We study the winner determination problem for three prevalent committee election rules: Chamberlin-Courant Approval Voting (CCA), Proportional Approval Voting (PAV), and Satisfaction Approval Voting (SAV). Axiomatic a...
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ISBN:
(纸本)9781450363099
We study the winner determination problem for three prevalent committee election rules: Chamberlin-Courant Approval Voting (CCA), Proportional Approval Voting (PAV), and Satisfaction Approval Voting (SAV). Axiomatic and algorithmic studies of elections under these rules have been conducted recently. It is known that the winner determination problem is NP-hard for CCA and PAV and polynomial-time solvable for SAV, if the input votes are dichotomous. Moreover, parameterized complexity of the two NP-hard cases has been examined with respect to some natural parameters such as the number of candidates or the number of votes. In this paper, we extend the above studies to committee elections with trichotomous votes and identify cases, where trichotomous votes lead to an increase of parameterized complexity. We also consider the maximin (or egalitarian) variations of the rules, where the minimum satisfaction of the voters is maximized.
We consider the word search problem in the BaumslagsGersten group GB. We show that the parameterized complexity of this problem, where the area of van Kampen diagram serves as a parameter, is polynomial in the length ...
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ISBN:
(纸本)9781450371001
We consider the word search problem in the BaumslagsGersten group GB. We show that the parameterized complexity of this problem, where the area of van Kampen diagram serves as a parameter, is polynomial in the length of the input and the parameter. This contrasts the well-known result that the Dehn function and the time complexity of the word search problem in GB are non-elementary.
In an iterative voting system, candidates are eliminated in consecutive rounds until either the set of remaining candidates does not change or a fixed number of rounds is reached. In this paper, we consider four promi...
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ISBN:
(纸本)9781450375184
In an iterative voting system, candidates are eliminated in consecutive rounds until either the set of remaining candidates does not change or a fixed number of rounds is reached. In this paper, we consider four prominent iterative voting systems, which are all based on positional scoring rules. The Hare and Coombs systems are based on the plurality and veto rules, respectively, while the Baldwin and Nanson systems are based on the Borda rule. We study the resistance of these four systems against shift bribery. Hereby, we consider both constructive and destructive settings. It is known that all four iterative voting systems are resistant to shift bribery, that is, both constructive and destructive shift bribery problems are NP-hard for these voting systems. We complement these NP-hardness results by examining parameterized complexity of the shift bribery problems with respect to some natural parameters. Our results provide further evidence for the observation that shift bribery problems for iterative voting systems are computationally harder than for the corresponding non-iterative cases. In addition, our reductions apply several techniques which might be useful for proving hardness results for other iterative voting systems.
Given a network modeled by a directed graph D = (V, A), it is natural to ask whether we can partition the vertex set of D into two disjoint subsets V-1, V-2 (called a 2-partition), such that the digraphs D[V-1], D[V-2...
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Given a network modeled by a directed graph D = (V, A), it is natural to ask whether we can partition the vertex set of D into two disjoint subsets V-1, V-2 (called a 2-partition), such that the digraphs D[V-1], D[V-2] induced by each of these has one of the two properties of interest. This question gives rise to a rich realm of combinatorial problems. The complexity of many such problems was determined in [2,3]. We analyze a subset of those problems from the viewpoint of parameterized complexity, and present a complete dichotomy of basic, natural properties. More precisely, given a directed graph D = (V, A) and two non-negative integers k(1) and k(2), we seek a 2-partition (V-1, V-2) of the vertex set V such that vertical bar V-1 vertical bar >= k(1), vertical bar V-2 vertical bar >= k(2), and each of the subdigraphs induced by V-1 and V-2 has a structural property as defined by the problem at hand-for example, D[V-1] is acyclic and D[V-2] is strongly connected. Specifically, we consider the following eight structural properties: being strongly connected;being connected;having an out-branching;having an in-branching;having minimum degree at least one;having minimum semi-degree at least one;being acyclic;and being complete. (C) 2019 Elsevier B.V. All rights reserved.
We consider the problem of finding a subcomplex K' of a simplicial complex K such that K' is homeomorphic to the 2-dimensional sphere, S-2. We study two variants of this problem. The first asks if there exists...
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We consider the problem of finding a subcomplex K' of a simplicial complex K such that K' is homeomorphic to the 2-dimensional sphere, S-2. We study two variants of this problem. The first asks if there exists such a K' with at most K triangles, and we show that this variant is W [1]-hard and, assuming the exponential time hypothesis, admits no n(o(root k))-time algorithm. We also give an algorithm that is tight with regard to this lower bound. The second problem is the dual of the first and asks if K' can be found by removing at most k triangles from K. This variant has an immediate O (3(k)poly(vertical bar K vertical bar))-time algorithm, and we show that it admits a polynomial kernelization to O (k(2)) triangles, as well as a polynomial compression to a weighted version with bit-size O (k log k).
Several recent papers obtained complexity results regarding the geodesic hull number hn(gd)(G) of a graph G. In this paper, we prove that determining whether hngd(G) <= k is W[2]-hard parameterized by k in diameter...
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Several recent papers obtained complexity results regarding the geodesic hull number hn(gd)(G) of a graph G. In this paper, we prove that determining whether hngd(G) <= k is W[2]-hard parameterized by k in diameter-two graphs and is W[1] -hard parameterized by tw +4, where tw is the treewidth of G. Despite this, for graphs with bounded treewidth tw, we prove that hngd(G) is computable in polynomial time O ((tw+2)(tw+5)n(2tw+5)). (C) 2019 Elsevier B.V. All rights reserved.
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