We study a generalization of the constraint satisfaction problem (CSP), the periodic constraint satisfaction problem. An input instance of the periodic CSP is a finite set of "generating" constraints over a ...
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We study a generalization of the constraint satisfaction problem (CSP), the periodic constraint satisfaction problem. An input instance of the periodic CSP is a finite set of "generating" constraints over a structured variable set that implicitly specifies a larger, possibly infinite set of constraints;the problem is to decide whether or not the larger set of constraints has a satisfying assignment. This model is natural for studying constraint networks consisting of constraints obeying a high degree of regularity or symmetry. Our main contribution is the identification of two broad polynomial-time tractable subclasses of the periodic CSP.
We initiate the study of external manipulations in STABLE MARRIAGE by considering several manipulative actions as well as several "desirable" manipulation goals. For instance, one goal is to make sure that a...
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ISBN:
(纸本)9783030579807;9783030579791
We initiate the study of external manipulations in STABLE MARRIAGE by considering several manipulative actions as well as several "desirable" manipulation goals. For instance, one goal is to make sure that a given pair of agents is matched in a stable solution, and this may be achieved by the manipulative action of reordering some agents' preference lists. We present a comprehensive study of the computational complexity of all problems arising in this way. We find several polynomial-time solvable cases as well as NP-hard ones. For the NP-hard cases, focusing on the natural parameter "budget" (that is, the number of manipulative actions), we also perform a parameterized complexity analysis and encounter parameterized hardness results.
We obtain a polynomial-time algorithm that, given input (A, b), where A = (B | N) ∈ ℤm ×n, m m ×m and b ∈ ℤm, finds a nonnegative integer solution to the system Ax = b or determines that no such solution e...
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作者:
Hamada, KokiMiyazaki, ShuichiOkamoto, KazuyaNTT Corp
3-9-11 Midori Cho Musashino Tokyo 1808585 Japan Kyoto Univ
Grad Sch Informat Sakyo Ku Yoshida Honmachi Kyoto 6068501 Japan Kyoto Univ
Acad Ctr Comp & Media Studies Sakyo Ku Yoshida Honmachi Kyoto 6068501 Japan Kyoto Univ Hosp
Div Med Informat Technol & Adm Planning Sakyo Ku 54 Kawaharacho Kyoto 6068507 Japan
In IWOCA 2019, Ruangwises and Itoh introduced stable noncrossing matchings, where participants of each side are aligned on each of two parallel lines, and no two matching edges are allowed to cross each other. They de...
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ISBN:
(纸本)9783030489656;9783030489663
In IWOCA 2019, Ruangwises and Itoh introduced stable noncrossing matchings, where participants of each side are aligned on each of two parallel lines, and no two matching edges are allowed to cross each other. They defined two stability notions, strongly stable noncrossing matching (SSNM) and weakly stable noncrossing matching (WSNM), depending on the strength of blocking pairs. They proved that a WSNM always exists and presented an O(n(2))-time algorithm to find one for an instance with n men and n women. They also posed open questions of the complexities of determining existence of an SSNM and finding a largest WSNM. In this paper, we show that both problems are solvable in polynomialtime. Our algorithms are applicable to extensions where preference lists may include ties, except for one case which we show to be NP-complete.
The goal of this thesis to contribute towards a computational complexity theory of statistical inference problems. In recent years, researchers have built evidence in favor of an emerging hypothesis that the class of ...
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The goal of this thesis to contribute towards a computational complexity theory of statistical inference problems. In recent years, researchers have built evidence in favor of an emerging hypothesis that the class of semi-definite programming (SDP) algorithms is optimal among for computationally efficient algorithms for a certain family of estimation problems. In this thesis, we present four main research efforts that refine this hypothesis and initiate preliminary efforts to go beyond it: • Optimal algorithms for private and robust estimation: We give the first polynomial-time algorithms for privately and robustly estimating a Gaussian distribution with optimal dependence on the dimension in the sample complexity. This adds the fundamental problem of private statistical estimation to a growing list of problems for which SDPs are optimal among polynomial-time algorithms. • Limitations of SDPs: Given independent standard Gaussian points in dimension d, for what values of (n, d) does there exist with high probability an origin-symmetric ellipsoid that simultaneously passes through all of the points? Based on strong numerical evidence, it was conjectured that the ellipsoid fitting problem transitions from feasible to infeasible as the number of points n increases, with a sharp threshold at n ∼ d 2/4; we resolve this conjecture up to logarithmic factors. A corollary of this result is that a canonical SDP-based algorithm fails to successfully solve inference problems involving low-rank matrix decompositions, independent component analysis, and principal component analysis. • New algorithms for discrepancy certification: We initiate the study of the algorithmic problem of certifying lower bounds on the discrepancy of random matrices, which has connections to conjecturally-hard average-case problems such as negatively-spiked PCA, the number-balancing problem and refuting random constraint satisfaction problems. We give the first polynomial-time algorithms with non-trivial
Background: Orthologs inference is the starting point of most comparative genomics studies, and a plethora of methods have been designed in the last decade to address this challenging task. In this paper we focus on t...
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Background: Orthologs inference is the starting point of most comparative genomics studies, and a plethora of methods have been designed in the last decade to address this challenging task. In this paper we focus on the problems of deciding consistency with a species tree (known or not) of a partial set of orthology/paralogy relationships C on a collection of n genes. Results: We give the first polynomial algorithm - more precisely a O(n(3)) time algorithm - to decide whether C is consistent, even when the species tree is unknown. We also investigate a biologically meaningful optimization version of these problems, in which we wish to minimize the number of duplication events;unfortunately, we show that all these optimization problems are NP-hard and are unlikely to have good polynomialtime approximation algorithms. Conclusions: Our polynomial algorithm for checking consistency has been implemented in Python and is available at https://***/UdeM-LBIT/OrthoPara-ConstraintChecker.
A vertex subset I of a graph G is called a k-path vertex cover if every path on k vertices in G contains at least one vertex from I. The k-P ath V ertex C over R econfiguration (k-PVCR) problem asks if one can transfo...
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A vertex subset I of a graph G is called a k-path vertex cover if every path on k vertices in G contains at least one vertex from I. The k-P ath V ertex C over R econfiguration (k-PVCR) problem asks if one can transform one k-path vertex cover into another via a sequence of kpath vertex covers where each intermediate member is obtained from its predecessor by applying a given reconfiguration rule exactly once. We investigate the computational complexity of k-PVCR from the viewpoint of graph classes under the well-known reconfiguration rules: TS, TJ, and TAR. The problem for k = 2, known as the Vertex Cover Reconfiguration (VCR) problem, has been well-studied in the literature. We show that certain known hardness results for VCR on different graph classes can be extended for k-PVCR. In particular, we prove a complexity dichotomy for k-PVCR on general graphs: on those whose maximum degree is three (and even planar), the problem is PSPACE-complete, while on those whose maximum degree is two (i.e., paths and cycles), the problem can be solved in polynomialtime. Additionally, we also design polynomial-time algorithms for k-PVCR on trees under each of TJ and TAR. Moreover, on paths, cycles, and trees, we describe how one can construct a reconfiguration sequence between two given k-path vertex covers in a yes-instance. In particular, on paths, our constructed reconfiguration sequence is shortest.
There has been a lot of research on dynamic lot sizing problems with different nonlinear cost structures due to capacitated production, minimum order quantity requirements, availability of quantity discounts, etc. Dev...
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There has been a lot of research on dynamic lot sizing problems with different nonlinear cost structures due to capacitated production, minimum order quantity requirements, availability of quantity discounts, etc. Developing optimal solutions efficiently for dynamic lot sizing models with nonlinear cost functions is a challenging topic. In this paper, we present a set of sufficient conditions such that if a single-item dynamic lot sizing problem satisfies these conditions, then the existence of a polynomial-time solution method for the problem is guaranteed. Several examples are presented to demonstrate the use of these sufficient conditions.
The main result of this paper is an 0([V] x [E]) time algorithm for deciding whether a given graph is a circle graph, that is, the intersection graph of a set of chords on a circle. The algorithm utilizes two new grap...
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The main result of this paper is an 0([V] x [E]) time algorithm for deciding whether a given graph is a circle graph, that is, the intersection graph of a set of chords on a circle. The algorithm utilizes two new graph-theoretic results, regarding necessary induced subgraphs of graphs having neither articulation points nor similar pairs of vertices. Furthermore, as a substep of the algorithm, it is shown how to find in 0([V] x [E]) time a decomposition of a graph into prime graphs, thereby improving on a result of Cunningham.
The classicalStable Roommatesproblem is to decide whether there exists a matching of an even number of agents such that no two agents which are not matched to each other would prefer to be with each other rather than ...
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The classicalStable Roommatesproblem is to decide whether there exists a matching of an even number of agents such that no two agents which are not matched to each other would prefer to be with each other rather than with their respectively assigned partners. We investigateStable Roommateswith complete (i.e., every agent can be matched with any other agent) or incomplete preferences, with ties (i.e., two agents are considered of equal value to some agent) or without ties. It is known that in general allowing ties makes the problem NP-complete. We provide algorithms forStable Roommatesthat are, compared to those in the literature, more efficient when the input preferences are complete and have some structural property, such as being narcissistic, single-peaked, and single-crossing. However, when the preferences are incomplete and have ties, we show that being single-peaked and single-crossing does not reduce the computational complexity-Stable Roommatesremains NP-complete.
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