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  • Satisfiability Algorithm for Syntactic Read- k -times Branching Programs
    Theory Comput. Syst. (IF 0.497) Pub Date : 2020-07-27
    Atsuki Nagao, Kazuhisa Seto, Junichi Teruyama

    The satisfiability of a given branching program is to determine whether there exists a consistent path from the root to 1-sink. In a syntactic read-k-times branching program, each variable appears at most k times in any path from the root to a sink. In a preliminary version of this paper, we provide a satisfiability algorithm for syntactic read-k-times branching programs with n variables and m edges

    更新日期:2020-07-27
  • Space Lower Bounds for the Signal Detection Problem
    Theory Comput. Syst. (IF 0.497) Pub Date : 2020-07-20
    Faith Ellen, Rati Gelashvili, Philipp Woelfel, Leqi Zhu

    Many shared memory algorithms have to deal with the problem of determining whether the value of a shared object has changed in between two successive accesses of that object by a process when the responses from both are the same. Motivated by this problem, we define the signal detection problem, which can be studied on a purely combinatorial level. Consider a system with n + 1 processes consisting

    更新日期:2020-07-20
  • Complexity and Algorithms for Semipaired Domination in Graphs
    Theory Comput. Syst. (IF 0.497) Pub Date : 2020-06-06
    Michael A. Henning, Arti Pandey, Vikash Tripathi

    For a graph G = (V, E) with no isolated vertices, a set \(D\subseteq V\) is called a semipaired dominating set of G if (i)D is a dominating set of G, and (ii)D can be partitioned into two element subsets such that the vertices in each two element set are at distance at most two. The minimum cardinality of a semipaired dominating set of G is called the semipaired domination number of G, and is denoted

    更新日期:2020-07-14
  • On the Average Case of MergeInsertion
    Theory Comput. Syst. (IF 0.497) Pub Date : 2020-06-30
    Florian Stober, Armin Weiß

    MergeInsertion, also known as the Ford-Johnson algorithm, is a sorting algorithm which, up to today, for many input sizes achieves the best known upper bound on the number of comparisons. Indeed, it gets extremely close to the information-theoretic lower bound. While the worst-case behavior is well understood, only little is known about the average case. This work takes a closer look at the average

    更新日期:2020-06-30
  • Consistent Query Answering for Primary Keys in Datalog
    Theory Comput. Syst. (IF 0.497) Pub Date : 2020-06-30
    Paraschos Koutris, Jef Wijsen

    We study the complexity of consistent query answering on databases that may violate primary key constraints. A repair of such a database is any consistent database that can be obtained by deleting a minimal set of tuples. For every Boolean query q, CERTAINTY(q) is the problem that takes a database as input and asks whether q evaluates to true on every repair. In Koutris and Wijsen (ACM Trans. Database

    更新日期:2020-06-30
  • Belga B-Trees
    Theory Comput. Syst. (IF 0.497) Pub Date : 2020-06-27
    Erik D. Demaine, John Iacono, Grigorios Koumoutsos, Stefan Langerman

    We revisitself-adjustingexternal memory tree data structures, which combine the optimal (and practical) worst-case I/O performances of B-trees, while adapting to the online distribution of queries. Our approach is analogous to undergoing efforts in the BST model, where Tango Trees (Demaine et al., SIAM J. Comput. 37(1), 240–251, 2007) were shown to be \(O(\log \log N)\)-competitive with the runtime

    更新日期:2020-06-27
  • Forward Looking Huffman Coding
    Theory Comput. Syst. (IF 0.497) Pub Date : 2020-06-25
    Shmuel T. Klein, Shoham Saadia, Dana Shapira

    Huffman coding is known to be optimal, yet its dynamic version may yield smaller compressed files. The best known bound is that the number of bits used by dynamic Huffman coding in order to encode a message of n characters is at most larger by n bits than the size of the file required by static Huffman coding. In particular, dynamic Huffman coding can also generate a larger encoded file than the static

    更新日期:2020-06-25
  • Dichotomy for Holant ∗ Problems on the Boolean Domain
    Theory Comput. Syst. (IF 0.497) Pub Date : 2020-06-22
    Jin-Yi Cai, Pinyan Lu, Mingji Xia

    Holant problems are a general framework to study counting problems. Both counting constraint satisfaction problems (#CSP) and graph homomorphisms are special cases. We prove a complexity dichotomy theorem for \(\text {Holant}^{*}(\mathcal {F})\), where \({\mathcal {F}}\) is a set of constraint functions on Boolean variables and taking complex values. The constraint functions need not be symmetric functions

    更新日期:2020-06-23
  • On Envy-Free Revenue Approximation for Combinatorial Buyers with Budgets
    Theory Comput. Syst. (IF 0.497) Pub Date : 2020-06-09
    Evangelos Markakis, Apostolos Ntokos, Orestis Telelis

    We study the computation of revenue-maximizing envy-free outcomes, in a monopoly market with budgeted buyers. Departing from previous works, we focus on buyers with combinatorial valuation functions, that are defined over subsets of distinct goods. Our results concern several classes of valuation functions. For single-minded budgeted buyers, we show a best possible polynomial-time approximation of

    更新日期:2020-06-09
  • Parameterized Complexity of Min-Power Asymmetric Connectivity
    Theory Comput. Syst. (IF 0.497) Pub Date : 2020-05-23
    Matthias Bentert, Roman Haag, Christian Hofer, Tomohiro Koana, André Nichterlein

    We investigate parameterized algorithms for the NP-hard problem Min-Power Asymmetric Connectivity (MinPAC) that has applications in wireless sensor networks. Given a directed arc-weighted graph, MinPAC asks for a strongly connected spanning subgraph minimizing the summed vertex costs. Here, the cost of each vertex is the weight of its heaviest outgoing arc in the chosen subgraph. We present linear-time

    更新日期:2020-05-23
  • Multiplication Algorithm Based on Collatz Function
    Theory Comput. Syst. (IF 0.497) Pub Date : 2020-05-15
    David Barina

    This article presents a new multiplication algorithm based on the Collatz function. Assuming the validity of the Collatz conjecture, the time complexity of multiplying two n-digit numbers is O(kn), where the k is the number of odd steps in the Collatz trajectory of the first multiplicand. Most likely, the algorithm is only of theoretical interest.

    更新日期:2020-05-15
  • Fast Algorithms for the Shortest Unique Palindromic Substring Problem on Run-Length Encoded Strings
    Theory Comput. Syst. (IF 0.497) Pub Date : 2020-05-09
    Kiichi Watanabe, Yuto Nakashima, Shunsuke Inenaga, Hideo Bannai, Masayuki Takeda

    For a string S, a palindromic substring S[i..j] is said to be a shortest unique palindromic substring (SUPS) for an interval [s,t] in S, if S[i..j] occurs exactly once in S, the interval [i,j] contains [s,t], and every palindromic substring containing [s,t] which is shorter than S[i..j] occurs at least twice in S. In this paper, we study the problem of answering SUPS queries on run-length encoded strings

    更新日期:2020-05-09
  • Unpopularity Factor in the Marriage and Roommates Problems
    Theory Comput. Syst. (IF 0.497) Pub Date : 2020-04-28
    Suthee Ruangwises, Toshiya Itoh

    Given a set A of n people, with each person having a preference list that ranks a subset of A as his/her acceptable partners in order of preference, we consider the Roommates Problem (rp) and the Marriage Problem (mp) of matching people with their partners. In rp there is no further restriction, while in mp only people of opposite genders can be acceptable partners. For a pair of matchings X and Y

    更新日期:2020-04-28
  • An Improved FPT Algorithm for Independent Feedback Vertex Set
    Theory Comput. Syst. (IF 0.497) Pub Date : 2020-04-25
    Shaohua Li, Marcin Pilipczuk

    We study the Independent Feedback Vertex Set problem — a variant of the classic Feedback Vertex Set problem where, given a graph G and an integer k, the problem is to decide whether there exists a vertex set \(S\subseteq V(G)\) such that G ∖ S is a forest and S is an independent set of size at most k. We present an \(\mathcal {O}^{\ast }((1+\varphi ^{2})^{k})\)-time FPT algorithm for this problem,

    更新日期:2020-04-25
  • Santha-Vazirani sources, deterministic condensers and very strong extractors
    Theory Comput. Syst. (IF 0.497) Pub Date : 2020-04-23
    Dmitry Gavinsky, Pavel Pudlák

    The notion of semi-random sources, also known as Santha-Vazirani (SV) sources, stands for a sequence of n bits, where the dependence of the i’th bit on the previousi − 1 bits is limited for every i ∈ [n]. If the dependence of the i’th bit on the remainingn − 1 bits is limited, then this is a strongSV-source. Even the strong SV -sources are known not to admit (universal) deterministic extractors, but

    更新日期:2020-04-23
  • Transition Property for Cube-Free Words
    Theory Comput. Syst. (IF 0.497) Pub Date : 2020-04-21
    Elena A. Petrova, Arseny M. Shur

    We study cube-free words over arbitrary non-unary finite alphabets and prove the following structural property: for every pair (u, v) of d-ary cube-free words, if u can be infinitely extended to the right and v can be infinitely extended to the left respecting the cube-freeness property, then there exists a “transition” word w over the same alphabet such that uwv is cube free. The crucial case is the

    更新日期:2020-04-21
  • Effective Categoricity of Automatic Equivalence and Nested Equivalence Structures
    Theory Comput. Syst. (IF 0.497) Pub Date : 2020-04-08
    Jacob Carson, Douglas Cenzer, Jeffrey B. Remmel

    We study automatic equivalence and nested equivalence structures. The goal is to compare and contrast these automatic structures with computable equivalence and nested equivalence structures. Equivalence structures \(\mathcal {A}\) may be characterized by their characters \(\chi ({\mathcal {A}})\) which encodes the number of equivalence classes of any given size. The characters of computably categorical

    更新日期:2020-04-08
  • Complexity of Fall Coloring for Restricted Graph Classes
    Theory Comput. Syst. (IF 0.497) Pub Date : 2020-04-08
    Juho Lauri, Christodoulos Mitillos

    We strengthen a result by Laskar and Lyle (Discrete Appl. Math. 157, 330–338 2009) by proving that it is NP-complete to decide whether a bipartite planar graph can be partitioned into three independent dominating sets. In contrast, we show that this is always possible for every maximal outerplanar graph with at least three vertices. Moreover, we extend their previous result by proving that deciding

    更新日期:2020-04-08
  • On the Fixed-Parameter Tractability of the Maximum Connectivity Improvement Problem
    Theory Comput. Syst. (IF 0.497) Pub Date : 2020-04-07
    Federico Corò, Gianlorenzo D’Angelo, Vahan Mkrtchyan

    In the Maximum Connectivity Improvement (MCI) problem, we are given a directed graph G = (V,E) and an integer B and we are asked to find B new edges to be added to G in order to maximize the number of connected pairs of vertices in the resulting graph. The MCI problem has been studied from the approximation point of view. In this paper, we approach it from the parameterized complexity perspective in

    更新日期:2020-04-07
  • First-Order Orbit Queries
    Theory Comput. Syst. (IF 0.497) Pub Date : 2020-04-04
    Shaull Almagor, Joël Ouaknine, James Worrell

    Orbit Problems are a class of fundamental reachability questions that arise in the analysis of discrete-time linear dynamical systems such as automata, Markov chains, recurrence sequences, and linear while loops. Instances of the problem comprise a dimension \(d\in \mathbb {N}\), a square matrix \(A\in \mathbb {Q}^{d\times d}\), and a query regarding the behaviour of some sets under repeated applications

    更新日期:2020-04-04
  • Conflict Free Version of Covering Problems on Graphs: Classical and Parameterized
    Theory Comput. Syst. (IF 0.497) Pub Date : 2020-02-28
    Pallavi Jain, Lawqueen Kanesh, Pranabendu Misra

    Let π be a family of graphs. In the classical π-Vertex Deletion problem, given a graph G and a positive integer k, the objective is to check whether there exists a subset S of at most k vertices such that G − S is in π. In this paper, we introduce the conflict free version of this classical problem, namely Conflict Free π-Vertex Deletion (CF-π-VD), and study this problem from the viewpoint of classical

    更新日期:2020-02-28
  • Correction to: Special Issue on Approximation and Online Algorithms
    Theory Comput. Syst. (IF 0.497) Pub Date : 2020-02-28
    Leah Epstein, Thomas Erlebach

    The original version of the article was inadvertently published with misinterpretations on author’s proof corrections on mathematical expressions.

    更新日期:2020-02-28
  • Longest Increasing Subsequence under Persistent Comparison Errors
    Theory Comput. Syst. (IF 0.497) Pub Date : 2020-02-20
    Barbara Geissmann

    We study the problem of computing a longest increasing subsequence in a sequence S of n distinct elements in the presence of persistent comparison errors. In this model, Braverman and Mossel (Noisy sorting without resampling, SODA 2008, pages 268–276, 2008) every comparison between two elements can return the wrong result with some fixed (small) probability p, and comparisons cannot be repeated. Computing

    更新日期:2020-02-20
  • Approximating Node-Weighted k -MST on Planar Graphs
    Theory Comput. Syst. (IF 0.497) Pub Date : 2020-02-03
    Jarosław Byrka, Mateusz Lewandowski, Joachim Spoerhase

    We study the problem of finding a minimum weight connected subgraph spanning at least k vertices on planar, node-weighted graphs. We give a (4 + ε)-approximation algorithm for this problem. We achieve this by utilizing the recent Lagrangian-multiplier preserving (LMP) primal-dual 3-approximation for the node-weighted prize-collecting Steiner tree problem by Byrka et al. (SWAT’16) and adopting an approach

    更新日期:2020-02-03
  • Correction to: Connecting Knowledge Compilation Classes and Width Parameters
    Theory Comput. Syst. (IF 0.497) Pub Date : 2020-01-25
    Antoine Amarilli, Florent Capelli, Mikaël Monet, Pierre Senellart

    The article title in the original publication contains an error. The correct title is presented in this Erratum. The online version of the original article can be found at: https://doi.org/10.1007/s00224-019-09930-2

    更新日期:2020-01-25
  • Deterministic Min-Cost Matching with Delays
    Theory Comput. Syst. (IF 0.497) Pub Date : 2020-01-06
    Yossi Azar, Amit Jacob Fanani

    We consider the online Minimum-Cost Perfect Matching with Delays (MPMD) problem introduced by Emek et al. (STOC 2016), in which a general metric space is given, and requests for points in space are submitted in different times in this space by an adversary. The goal is to match requests, while minimizing the sum of distances between matched pairs in addition to the time intervals passed from the moment

    更新日期:2020-01-06
  • Countable Sofic Shifts with a Periodic Direction
    Theory Comput. Syst. (IF 0.497) Pub Date : 2019-12-27
    Ilkka Törmä

    As a variant of the equal entropy cover problem, we ask whether all multidimensional sofic shifts with countably many configurations have SFT covers with countably many configurations. We answer this question in the negative by presenting explicit counterexamples. We formulate necessary conditions for a vertically periodic shift space to have a countable SFT cover, and prove that they are sufficient

    更新日期:2019-12-27
  • Generalized Graph k -Coloring Games
    Theory Comput. Syst. (IF 0.497) Pub Date : 2019-12-20
    Raffaello Carosi, Gianpiero Monaco

    We investigate pure Nash equilibria in generalized graphk-coloring games where we are given an edge-weighted undirected graph together with a set of k colors. Nodes represent players and edges capture their mutual interests. The strategy set of each player consists of k colors. The utility of a player v in a given state or coloring is given by the sum of the weights of edges {v, u} incident to v such

    更新日期:2019-12-20
  • Optimizing Social Welfare for Network Bargaining Games in the Face of Instability, Greed and Idealism
    Theory Comput. Syst. (IF 0.497) Pub Date : 2019-12-04
    T.-H. Hubert Chan, Fei Chen, Li Ning

    Stable and balanced outcomes of network bargaining games have been investigated recently, but the existence of such outcomes requires that the linear program relaxation of a certain maximum matching problem have integral optimal solution. We propose an alternative model for network bargaining games in which each edge acts as a player, who proposes how to split the weight of the edge among the two incident

    更新日期:2019-12-04
  • On Normality in Shifts of Finite Type
    Theory Comput. Syst. (IF 0.497) Pub Date : 2019-12-04
    Nicolás Álvarez, Olivier Carton

    In this paper we consider the notion of normality of sequences in shifts of finite type. A sequence is normal if the frequency of each block exists and is equal to the Parry measure of the block. We give a characterization of normality in terms of incompressibility by lossless transducers. The result was already known in the case of the full shift.

    更新日期:2019-12-04
  • Distribution Policies for Datalog
    Theory Comput. Syst. (IF 0.497) Pub Date : 2019-12-04
    Bas Ketsman, Aws Albarghouthi, Paraschos Koutris

    Modern data management systems extensively use parallelism to speed up query processing over massive volumes of data. This trend has inspired a rich line of research on how to formally reason about the parallel complexity of join computation. In this paper, we go beyond joins and study the parallel evaluation of recursive queries. We introduce a novel framework to reason about multi-round evaluation

    更新日期:2019-12-04
  • On Limitations of Structured (Deterministic) DNNFs
    Theory Comput. Syst. (IF 0.497) Pub Date : 2019-12-04
    Beate Bollig, Matthias Buttkus

    The study of representations for propositional theories has been a central subject in knowledge compilation. Many known representations of propositional knowledge bases are restricted negation normal form circuits (NNFs) or binary decision diagrams. Sentential decision diagrams (SDDs) are one of them, by definition they are restricted structured deterministic DNNFs and more general than ordered binary

    更新日期:2019-12-04
  • Optimal Dislocation with Persistent Errors in Subquadratic Time
    Theory Comput. Syst. (IF 0.497) Pub Date : 2019-12-03
    Barbara Geissmann, Stefano Leucci, Chih-Hung Liu, Paolo Penna

    We study the problem of sorting N elements in the presence of persistent errors in comparisons: In this classical model, each comparison between two elements is wrong independently with some probability up to p, but repeating the same comparison gives always the same result. In this model, it is impossible to reliably compute a perfectly sorted permutation of the input elements. Rather, the quality

    更新日期:2019-12-03
  • Scheduling MapReduce Jobs on Identical and Unrelated Processors
    Theory Comput. Syst. (IF 0.497) Pub Date : 2019-11-29
    Dimitris Fotakis, Ioannis Milis, Orestis Papadigenopoulos, Vasilis Vassalos, Georgios Zois

    We consider non-preemptive scheduling of MapReduce jobs consisting of multiple map-reduce rounds so as to minimize their average weighted completion time on identical or unrelated processor environments. For identical processors, we present LP-based O(1)-approximation algorithms, while for unrelated processors the approximation ratio naturally depends on the maximum number of rounds of any job (which

    更新日期:2019-11-29
  • Advice Complexity of Priority Algorithms
    Theory Comput. Syst. (IF 0.497) Pub Date : 2019-11-13
    Allan Borodin, Joan Boyar, Kim S. Larsen, Denis Pankratov

    The priority model of “greedy-like” algorithms was introduced by Borodin, Nielsen, and Rackoff in 2002. We augment this model by allowing priority algorithms to have access to advice, i.e., side information precomputed by an all-powerful oracle. Obtaining lower bounds in the priority model without advice can be challenging and may involve intricate adversary arguments. Since the priority model with

    更新日期:2019-11-13
  • Extension Complexity of Formal Languages
    Theory Comput. Syst. (IF 0.497) Pub Date : 2019-11-06
    Hans Raj Tiwary

    In this article we undertake a study of extension complexity from the perspective of formal languages. We define a natural way to associate a family of polytopes with binary languages. This allows us to define the notion of extension complexity of formal languages. We prove several closure properties of languages admitting compact extended formulations. Furthermore, we give a sufficient machine characterization

    更新日期:2019-11-06
  • Sitting Closer to Friends than Enemies, Revisited.
    Theory Comput. Syst. (IF 0.497) Pub Date : 2015-08-25
    Marek Cygan,Marcin Pilipczuk,Michał Pilipczuk,Jakub Onufry Wojtaszczyk

    Signed graphs, i.e., undirected graphs with edges labelled with a plus or minus sign, are commonly used to model relationships in social networks. Recently, Kermarrec and Thraves (2011) initiated the study of the problem of appropriately visualising the network: They asked whether any signed graph can be embedded into the metric space [Formula: see text] in such a manner that every vertex is closer

    更新日期:2019-11-01
  • [Formula: see text]-Approximation for Graphic TSP.
    Theory Comput. Syst. (IF 0.497) Pub Date : 2014-01-01
    Marcin Mucha

    The Travelling Salesman Problem is one of the fundamental and intensively studied problems in approximation algorithms. For more than 30 years, the best algorithm known for general metrics has been Christofides's algorithm with an approximation factor of [Formula: see text], even though the so-called Held-Karp LP relaxation of the problem is conjectured to have the integrality gap of only [Formula:

    更新日期:2019-11-01
  • Improved Distance Queries and Cycle Counting by Frobenius Normal Form.
    Theory Comput. Syst. (IF 0.497) Pub Date : null
    Piotr Sankowski,Karol Węgrzycki

    Consider an unweighted, directed graph G with the diameter D. In this paper, we introduce the framework for counting cycles and walks of given length in matrix multiplication time O ~ ( n ω ) . The framework is based on the fast decomposition into Frobenius normal form and the Hankel matrix-vector multiplication. It allows us to solve the All-Nodes Shortest Cycles, All-Pairs All Walks problems efficiently

    更新日期:2019-11-01
  • Limits of Schema Mappings.
    Theory Comput. Syst. (IF 0.497) Pub Date : null
    Phokion G Kolaitis,Reinhard Pichler,Emanuel Sallinger,Vadim Savenkov

    Schema mappings have been extensively studied in the context of data exchange and data integration, where they have turned out to be the right level of abstraction for formalizing data inter-operability tasks. Up to now and for the most part, schema mappings have been studied as static objects, in the sense that each time the focus has been on a single schema mapping of interest or, in the case of

    更新日期:2019-11-01
  • Complexity and Expressive Power of Weakly Well-Designed SPARQL.
    Theory Comput. Syst. (IF 0.497) Pub Date : null
    Mark Kaminski,Egor V Kostylev

    SPARQL is the standard query language for RDF data. The distinctive feature of SPARQL is the OPTIONAL operator, which allows for partial answers when complete answers are not available due to lack of information. However, optional matching is computationally expensive-query answering is PSPACE-complete. The well-designed fragment of SPARQL achieves much better computational properties by restricting

    更新日期:2019-11-01
  • Motivating Time-Inconsistent Agents: A Computational Approach.
    Theory Comput. Syst. (IF 0.497) Pub Date : null
    Susanne Albers,Dennis Kraft

    We study the complexity of motivating time-inconsistent agents to complete long term projects in a graph-based planning model proposed by Kleinberg and Oren (2014). Given a task graph G with n nodes, our objective is to guide an agent towards a target node t under certain budget constraints. The crux is that the agent may change its strategy over time due to its present-bias. We consider two strategies

    更新日期:2019-11-01
  • Finding Cactus Roots in Polynomial Time.
    Theory Comput. Syst. (IF 0.497) Pub Date : null
    Petr A Golovach,Dieter Kratsch,Daniël Paulusma,Anthony Stewart

    A graph H is a square root of a graph G, or equivalently, G is the square of H, if G can be obtained from H by adding an edge between any two vertices in H that are of distance 2. The Square Root problem is that of deciding whether a given graph admits a square root. The problem of testing whether a graph admits a square root which belongs to some specified graph class ℋ is called the ℋ -Square Root

    更新日期:2019-11-01
  • Designing Cost-Sharing Methods for Bayesian Games.
    Theory Comput. Syst. (IF 0.497) Pub Date : null
    George Christodoulou,Stefano Leonardi,Alkmini Sgouritsa

    We study the design of cost-sharing protocols for two fundamental resource allocation problems, the Set Cover and the Steiner Tree Problem, under environments of incomplete information (Bayesian model). Our objective is to design protocols where the worst-case Bayesian Nash equilibria have low cost, i.e. the Bayesian Price of Anarchy (PoA) is minimized. Although budget balance is a very natural requirement

    更新日期:2019-11-01
  • On the Stab Number of Rectangle Intersection Graphs
    Theory Comput. Syst. (IF 0.497) Pub Date : 2019-09-14
    Dibyayan Chakraborty, Mathew C. Francis

    We introduce the notion of stab number and exact stab number of rectangle intersection graphs, otherwise known as graphs of boxicity at most 2. A graph G is said to be a k-stabbable rectangle intersection graph, or k-SRIG for short, if it has a rectangle intersection representation in which k horizontal lines can be chosen such that each rectangle is intersected by at least one of them. If there exists

    更新日期:2019-09-14
  • An Optimally-Competitive Algorithm for Maximum Online Perfect Bipartite Matching with i.i.d. Arrivals
    Theory Comput. Syst. (IF 0.497) Pub Date : 2019-09-07
    Minjun Chang, Dorit S. Hochbaum, Quico Spaen, Mark Velednitsky

    We present an optimally-competitive algorithm for the problem of maximum online perfect bipartite matching with i.i.d. arrivals. In this problem, we are given a known set of workers, a distribution over job types, and non-negative utility weights for each pair of worker and job types. At each time step, a job is drawn i.i.d. from the distribution over job types. Upon arrival, the job must be irrevocably

    更新日期:2019-09-07
  • On the Tree Conjecture for the Network Creation Game
    Theory Comput. Syst. (IF 0.497) Pub Date : 2019-08-16
    Davide Bilò, Pascal Lenzner

    Selfish Network Creation focuses on modeling real world networks from a game-theoretic point of view. One of the classic models by Fabrikant et al. (2003) is the network creation game, where agents correspond to nodes in a network which buy incident edges for the price of α per edge to minimize their total distance to all other nodes. The model is well-studied but still has intriguing open problems

    更新日期:2019-08-16
  • Enumeration Complexity of Conjunctive Queries with Functional Dependencies
    Theory Comput. Syst. (IF 0.497) Pub Date : 2019-08-16
    Nofar Carmeli, Markus Kröll

    We study the complexity of enumerating the answers of Conjunctive Queries (CQs) in the presence of Functional Dependencies (FDs). Our focus is on the ability to list output tuples with a constant delay in between, following a linear-time preprocessing. A known dichotomy classifies the acyclic self-join-free CQs into those that admit such enumeration, and those that do not. However, this classification

    更新日期:2019-08-16
  • Connecting Knowledge Compilation Classes Width Parameters
    Theory Comput. Syst. (IF 0.497) Pub Date : 2019-06-10
    Antoine Amarilli, Florent Capelli, Mikaël Monet, Pierre Senellart

    The field of knowledge compilation establishes the tractability of many tasks by studying how to compile them to Boolean circuit classes obeying some requirements such as structuredness, decomposability, and determinism. However, in other settings such as intensional query evaluation on databases, we obtain Boolean circuits that satisfy some width bounds, e.g., they have bounded treewidth or pathwidth

    更新日期:2019-06-10
  • Additive Number Theory via Automata Theory
    Theory Comput. Syst. (IF 0.497) Pub Date : 2019-05-29
    Aayush Rajasekaran, Jeffrey Shallit, Tim Smith

    We show how some problems in additive number theory can be attacked in a novel way, using techniques from the theory of finite automata. We start by recalling the relationship between first-order logic and finite automata, and use this relationship to solve several problems involving sums of numbers defined by their base-2 and Fibonacci representations. Next, we turn to harder results. Recently, Cilleruelo

    更新日期:2019-05-29
  • A More General Theory of Static Approximations for Conjunctive Queries
    Theory Comput. Syst. (IF 0.497) Pub Date : 2019-05-10
    Pablo Barceló, Miguel Romero, Thomas Zeume

    Conjunctive query (CQ) evaluation is NP-complete, but becomes tractable for fragments of bounded hypertreewidth. Approximating a hard CQ by a query from such a fragment can thus allow for an efficient approximate evaluation. While underapproximations (i.e., approximations that return correct answers only) are well-understood, the dual notion of overapproximations (i.e, approximations that return complete

    更新日期:2019-05-10
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