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  • A Framework For Designing Space-Efficient Dictionaries for Parameterized and Order-Preserving Matching
    Theor. Comput. Sci. (IF 0.747) Pub Date : 2020-11-20
    Arnab Ganguly; Wing-Kai Hon; Kunihiko Sadakane; Rahul Shah; Sharma V. Thankachan; Yilin Yang

    Let P be a collection of d patterns {P1,P2,…,Pd} of total length n characters, which are chosen from an alphabet Σ of size σ. Given a text T (over Σ), the dictionary indexing problem is to create a data structure using which we can report all positions j (called occurrences) where at least one of the patterns Pi∈P is a match with the same-length substring of T that starts at j. We consider this problem

    更新日期:2020-11-21
  • Computing a Longest Common Almost-Increasing Subsequence of Two Sequences
    Theor. Comput. Sci. (IF 0.747) Pub Date : 2020-11-20
    Toan Thang Ta; Yi-Kung Shieh; Chin Lung Lu

    Given a positive constant c, a sequence S=〈s1,s2,…,sk〉 of k numbers is said to be almost increasing if and only if si>max1≤j

    更新日期:2020-11-21
  • On the area requirements of planar straight-line orthogonal drawings of ternary trees
    Theor. Comput. Sci. (IF 0.747) Pub Date : 2020-11-20
    Barbara Covella; Fabrizio Frati; Maurizio Patrignani

    In this paper, we study the area requirements of planar straight-line orthogonal drawings of ternary trees. We prove that every ternary tree admits such a drawing in sub-quadratic area. Further, we present upper bounds, the outcomes of an experimental evaluation, and a conjecture on the area requirements of planar straight-line orthogonal drawings of complete ternary trees. Finally, we present a polynomial

    更新日期:2020-11-21
  • On bounded linear codes and the commutative equivalence
    Theor. Comput. Sci. (IF 0.747) Pub Date : 2020-11-20
    Arturo Carpi; Flavio D'Alessandro

    The problem of the commutative equivalence of semigroups generated by semi-linear languages is studied. In particular conditions ensuring that the Kleene closure of a bounded semi-linear code is commutatively equivalent to a regular language are investigated.

    更新日期:2020-11-21
  • Influence Maximization in the Presence of Vulnerable Nodes: A Ratio Perspective
    Theor. Comput. Sci. (IF 0.747) Pub Date : 2020-11-20
    Huiping Chen; Grigorios Loukides; Solon P. Pissis; Hau Chan

    Influence maximization is a key problem seeking to identify users who will diffuse information to influence the largest number of other users in a social network. A drawback of the influence maximization problem is that it could be socially irresponsible to influence users many of whom would be harmed, due to their demographics, health conditions, or socioeconomic characteristics (e.g., predominantly

    更新日期:2020-11-21
  • Tight Upper and Lower Bounds on Suffix Tree Breadth
    Theor. Comput. Sci. (IF 0.747) Pub Date : 2020-11-20
    Golnaz Badkobeh; Paweł Gawrychowski; Juha Kärkkäinen; Simon J. Puglisi; Bella Zhukova

    The suffix tree — the compacted trie of all the suffixes of a string — is the most important and widely-used data structure in string processing. We consider a natural combinatorial question about suffix trees: for a string S of length n, how many nodes νS(d) can there be at (string) depth d in its suffix tree? We prove ν(n,d)=maxS∈Σn⁡νS(d) is O((n/d)log⁡(n/d)), and show that this bound is asymptotically

    更新日期:2020-11-21
  • Optimal skeleton and reduced Huffman trees
    Theor. Comput. Sci. (IF 0.747) Pub Date : 2020-11-20
    Shmuel T. Klein; Jakub Radoszewski; Tamar C. Serebro; Dana Shapira

    A skeleton Huffman tree is a Huffman tree from which all full subtrees of depth h≥1 have been pruned. Skeleton Huffman trees are used to save storage and enhance processing time in several applications such as decoding, compressed pattern matching and wavelet trees for random access. A reduced skeleton tree prunes the skeleton Huffman tree further to an even smaller tree. The resulting more compact

    更新日期:2020-11-21
  • Maximal Unbordered Factors of Random Strings
    Theor. Comput. Sci. (IF 0.747) Pub Date : 2020-11-19
    Patrick Hagge Cording; Travis Gagie; Mathias Bæk Tejs Knudsen; Tomasz Kociumaka

    A border of a string is a non-empty prefix of the string that is also a suffix of the string, and a string is unbordered if it has no border other than itself. Loptev, Kucherov, and Starikovskaya [CPM'15] conjectured the following: If we pick a string of length n from a fixed non-unary alphabet uniformly at random, then the expected maximum length of its unbordered factors is n−O(1). We confirm this

    更新日期:2020-11-19
  • Proof of a conjecture on 2-isometric words
    Theor. Comput. Sci. (IF 0.747) Pub Date : 2020-11-19
    Jianxin Wei

    Let Fk be the family of the binary words containing exactly k 0s. Ilić, Klavžar and Rho constructed an infinite subfamily of 2-isometric but not 3-isometric words among F2. Wei, Yang and Wang further found there are 2-isometric but not 3-isometric words among Fk for all k∈{2,5,6} and k≥8, and they conjectured that F1, F3, F4 and F7 are the only families in which there are not 2-isometric but not 3-isometric

    更新日期:2020-11-19
  • A Simplified Run Time Analysis of the Univariate Marginal Distribution Algorithm on LeadingOnes
    Theor. Comput. Sci. (IF 0.747) Pub Date : 2020-11-19
    Benjamin Doerr; Martin S. Krejca

    With elementary means, we prove a stronger run time guarantee for the univariate marginal distribution algorithm (UMDA) optimizing the LeadingOnes benchmark function in the desirable regime with low genetic drift. If the population size is at least quasilinear, then, with high probability, the UMDA samples the optimum in a number of iterations that is linear in the problem size divided by the logarithm

    更新日期:2020-11-19
  • Revisiting the Prefer-same and Prefer-opposite de Bruijn sequence constructions
    Theor. Comput. Sci. (IF 0.747) Pub Date : 2020-11-19
    Abbas Alhakim; Evan Sala; Joe Sawada

    We present a simple greedy algorithm to construct the prefer-same de Bruijn sequence and prove that it is equivalent to the more complex algorithm first stated by Eldert et al. without proof [AIEE Transactions 77 (1958)], and later by Fredricksen [SIAM Review 24 (1982)]. Then we prove that the resulting sequence has the lexicographically largest run-length representation among all de Bruijn sequences

    更新日期:2020-11-19
  • Space-efficient construction of compressed suffix trees
    Theor. Comput. Sci. (IF 0.747) Pub Date : 2020-11-19
    Nicola Prezza; Giovanna Rosone

    We show how to build several data structures of central importance to string processing by taking as input the Burrows-Wheeler transform (BWT) and using small extra working space. Let n be the text length and σ be the alphabet size. We first provide two algorithms that enumerate all LCP values and suffix tree intervals in O(nlog⁡σ) time using just o(nlog⁡σ) bits of working space on top of the input

    更新日期:2020-11-19
  • The Maximum Colorful Arborescence problem: How (computationally) hard can it be?
    Theor. Comput. Sci. (IF 0.747) Pub Date : 2020-11-19
    Guillaume Fertin; Julien Fradin; Géraldine Jean

    Given a vertex-colored arc-weighted directed acyclic graph G, the Maximum Colorful Subtree problem (or MCS) aims at finding an arborescence of maximum weight in G, in which no color appears more than once. The problem was originally introduced in [1] in the context of de novo identification of metabolites by tandem mass spectrometry. However, a thorough analysis of the initial motivation shows that

    更新日期:2020-11-19
  • A fixed point theorem in rough semi-linear uniform spaces
    Theor. Comput. Sci. (IF 0.747) Pub Date : 2020-11-19
    Pankaj Kumar Singh; Surabhi Tiwari

    The fixed point theory has applications in various fields of science and engineering. In this paper, we introduce the concept of fixed points in the framework of rough set theory and discuss its application in the contraction of digital images. We scrutinize a rough semi-linear uniform space and prove a fixed point theorem for a rough semi-linear uniform space.

    更新日期:2020-11-19
  • On the Computing Powers of L-reductions of Insertion Languages
    Theor. Comput. Sci. (IF 0.747) Pub Date : 2020-11-19
    Fumiya Okubo; Takashi Yokomori

    We investigate the computing power of the following language operation %: Given two languages L1 over Σ and L2 over Γ with Γ⊂Σ, we consider the language operation L1%L2={u0u1⋯un|∃u=u0v1u1⋯vnun∈L1 and ∃vi∈L2(1≤∀i≤n)}. In this case we say that L(=L1%L2) is the L2-reduction of L1. This is extended to the language families as follows: L1%L2={L1%L2|L1∈L1,L2∈L2}. Among many works concerning Dyck-reductions

    更新日期:2020-11-19
  • Towards a real time algorithm for parameterized longest common prefix computation
    Theor. Comput. Sci. (IF 0.747) Pub Date : 2020-11-19
    Amihood Amir; Eitan Kondratovsky

    Parameterized matching has proven to be an efficient and useful tool for detecting code duplications. This paper presents a technique for calculating parameterized Longest Common Prefix (plcp) in constant time based on the knowledge about the plcp of the following suffixes. Using this technique, online p-suffix tree construction can be done in worst case time O(log⁡n) per input symbol. Searching for

    更新日期:2020-11-19
  • The vertex-pancyclicity of data center networks
    Theor. Comput. Sci. (IF 0.747) Pub Date : 2020-11-19
    Rong-Xia Hao; Zengxian Tian

    The k-dimensional data center network with n-port switches, denoted by Dk,n, has been proposed for data centers as a server centric network structure. Wang et al. had proved that Dk,n is Hamiltonian-connected for k≥0 and n≥2 except for (k,n)=(1,2). In this paper, we prove that for any edge (u,v) in a complete subgraph Kn of Dk,n, there is a cycle of every length from 3 to |V(Dk,n)| passing through

    更新日期:2020-11-19
  • Automedian sets of permutations: direct sum and shuffle
    Theor. Comput. Sci. (IF 0.747) Pub Date : 2020-11-19
    Charles Desharnais; Sylvie Hamel

    Given a set A⊆Sn of m permutations of {1,2,…,n} and a distance function d, the median problem consists in finding the set M(A) of all the permutations that are the “closest” of this set A. In this article we study the automedian case of the problem, i.e. when A=M(A), under the Kendall-τ distance. We show that automedian sets of permutations are closed under the direct sum operation and also, when some

    更新日期:2020-11-19
  • Stability of termination and sufficient-completeness under pushouts via amalgamation
    Theor. Comput. Sci. (IF 0.747) Pub Date : 2020-09-15
    Daniel Găină; Masaki Nakamura; Kazuhiro Ogata; Kokichi Futatsugi

    In the present study, we provide conditions for the existence of pushouts of signature morphisms in constructor-based order-sorted algebra, and then we prove that reducibility and termination of term rewriting systems are closed under pushouts. Under the termination assumption, reducibility is equivalent to sufficient-completeness, which is crucial for proving several important properties in computing

    更新日期:2020-11-16
  • Parallel rewriting of attributed graphs
    Theor. Comput. Sci. (IF 0.747) Pub Date : 2020-09-15
    Thierry Boy de la Tour; Rachid Echahed

    Some computations can be elegantly presented as the parallel or simultaneous application of rules. This is the case of cellular automata and of simultaneous assignments in Python. In both cases the expected result cannot be obtained by a sequential application of rules. A general framework of attributed graph transformations is proposed where such computations can be expressed and analyzed. Determinism

    更新日期:2020-11-16
  • Anti-unification and the theory of semirings
    Theor. Comput. Sci. (IF 0.747) Pub Date : 2020-10-22
    David M. Cerna

    It was recently shown that anti-unification over an equational theory consisting of only unit equations (more than one) is nullary. Such pure theories are artificial and are of little effect on practical aspects of anti-unification. In this work, we extend these nullarity results to the theory of semirings, a heavily studied theory with many practical applications. Furthermore, our argument holds over

    更新日期:2020-11-16
  • Treasure evacuation with one robot on a disk
    Theor. Comput. Sci. (IF 0.747) Pub Date : 2020-11-16
    Konstantinos Georgiou; George Karakostas; Evangelos Kranakis

    A robot is located at a point in the plane. A treasure and an exit, both stationary, are located at unknown (to the robot) positions both at distance one from the robot. Starting from its initial position, the robot aims to fetch the treasure to the exit. At any time the robot can move anywhere on the disk with constant speed. The robot detects an interesting point (treasure or exit) only if it passes

    更新日期:2020-11-16
  • Time-energy tradeoffs for evacuation by two robots in the wireless model
    Theor. Comput. Sci. (IF 0.747) Pub Date : 2020-11-13
    Jurek Czyzowicz; Konstantinos Georgiou; Ryan Killick; Evangelos Kranakis; Danny Krizanc; Manuel Lafond; Lata Narayanan; Jaroslav Opatrny; Sunil Shende

    Two robots stand at the origin of the infinite line and are tasked with searching collaboratively for an exit at an unknown location on the line. They can travel at maximum speed b and can change speed or direction at any time. The two robots can communicate with each other at any distance and at any time. The task is completed when the last robot arrives at the exit and evacuates. We study time-energy

    更新日期:2020-11-13
  • On the price of stability of some simple graph-based hedonic games
    Theor. Comput. Sci. (IF 0.747) Pub Date : 2020-11-13
    Christos Kaklamanis; Panagiotis Kanellopoulos; Konstantinos Papaioannou; Dimitris Patouchas

    We consider graph-based hedonic games such as simple symmetric fractional hedonic games and social distance games, where a group of utility maximizing players have hedonic preferences over the players' set, and wish to be partitioned into clusters so that they are grouped together with players they prefer. The players are nodes in a connected graph and their preferences are defined so that shorter

    更新日期:2020-11-13
  • Bounding Game Temperature using Confusion Intervals
    Theor. Comput. Sci. (IF 0.747) Pub Date : 2020-11-13
    Svenja Huntemann; Richard J. Nowakowski; Carlos Pereira dos Santos

    We consider bounds for the temperatures of combinatorial games. Our first result gives an upper bound on the temperatures of the positions of a ruleset in terms of the lengths of the confusion intervals of these positions. We give an example to show that this bound is tight. Our second main result is a method to find a bound for the lengths of the confusion intervals. This pair of results constitutes

    更新日期:2020-11-13
  • On the trace subshifts of fractional multiplication automata
    Theor. Comput. Sci. (IF 0.747) Pub Date : 2020-11-12
    Johan Kopra

    We address the dynamics of the cellular automaton (CA) that multiplies by p/q in base pq (for coprime p>q>1) by studying its trace subshift. We present a conjugacy of the trace to a previously studied base-p/q numeration system. We also show that the trace subshift is not synchronizing and in particular not sofic. As a byproduct we compute its complexity function and we conclude by presenting an example

    更新日期:2020-11-12
  • Being a permutation is also orthogonal to one-wayness in quantum world: Impossibilities of quantum one-way permutations from one-wayness primitives
    Theor. Comput. Sci. (IF 0.747) Pub Date : 2020-11-12
    Shujiao Cao; Rui Xue

    In this paper, three impossible results for one-way permutations in the quantum world are obtained. The first one is the impossibility of fully black-box reduction from one-way permutations to one-way functions in a quantum setting. The two-oracle method is the main technique adopted in our proof that was originally proposed by Hsiao and Reyzin, and extended later to a quantum setting by Hosoyamada

    更新日期:2020-11-12
  • Equitable list tree-coloring of bounded treewidth graphs
    Theor. Comput. Sci. (IF 0.747) Pub Date : 2020-11-12
    Yan Li; Xin Zhang

    The equitable list tree-coloring model is an useful tool to formulate a structure decomposition problem on the complex network with some security considerations. In this paper, it is proved that the equitable list vertex arboricity of every graph with treewidth ω is at most ⌈Δ(G)/2⌉+ω−2 whenever Δ(G)≥4ω−1, and moreover, if such a graph does not contain K3,3 as a topological minor, then its equitable

    更新日期:2020-11-12
  • A continuous strategy for collisionless gathering
    Theor. Comput. Sci. (IF 0.747) Pub Date : 2020-11-12
    Shouwei Li; Christine Markarian; Friedhelm Meyer auf der Heide; Pavel Podlipyan

    Over the past decades, the Gathering problem, which asks to gather a group of robots in finite time given some restrictions, has been intensively studied. In this paper, we are given a group of n autonomous, dimensionless, deterministic, and anonymous robots, with bounded viewing range. Assuming a continuous time model, the goal is to gather these robots into one point in finite time. We introduce

    更新日期:2020-11-12
  • Beyond Pointwise Submodularity: Non-Monotone Adaptive Submodular Maximization in Linear Time
    Theor. Comput. Sci. (IF 0.747) Pub Date : 2020-11-11
    Shaojie Tang

    In this paper, we study the non-monotone adaptive submodular maximization problem subject to a cardinality constraint. We first revisit the adaptive random greedy algorithm proposed in [13], where they show that this algorithm achieves a 1/e approximation ratio if the objective function is adaptive submodular and pointwise submodular. It is not clear whether the same guarantee holds under adaptive

    更新日期:2020-11-12
  • A combinatorial view on string attractors
    Theor. Comput. Sci. (IF 0.747) Pub Date : 2020-11-10
    Sabrina Mantaci; Antonio Restivo; Giuseppe Romana; Giovanna Rosone; Marinella Sciortino

    The notion of string attractor has recently been introduced in [Prezza, 2017] and studied in [Kempa and Prezza, 2018] to provide a unifying framework for known dictionary-based compressors. A string attractor for a word w=w1w2⋯wn is a subset Γ of the positions {1,…,n}, such that all distinct factors of w have an occurrence crossing at least one of the elements of Γ. In this paper we explore the notion

    更新日期:2020-11-12
  • Finding maximum sum segments in sequences with uncertainty
    Theor. Comput. Sci. (IF 0.747) Pub Date : 2020-11-10
    Hung-I Yu; Tien-Ching Lin; D.T. Lee

    Given a sequence of n numbers and two positive integers L and U with L≤U, the maximum sum segment problem is to find a segment of the sequence with length between L and U such that the sum of numbers in this segment is maximized. In this paper, we introduce the concept of uncertainty into the maximum sum segment problem, where each of the n numbers of the sequence is not given as an exact value but

    更新日期:2020-11-12
  • Exploration of Dynamic Tori by Multiple Agents
    Theor. Comput. Sci. (IF 0.747) Pub Date : 2020-11-10
    Tsuyoshi Gotoh; Yuichi Sudo; Fukuhito Ooshita; Hirotsugu Kakugawa; Toshimitsu Masuzawa

    Mobile agents (agents) are objects which can migrate autonomously in a distributed system and execute actions at visited nodes. One of the most fundamental problems of agents is exploration, which requires that each node should be visited by at least one agent. For a long time, researchers focus on exploration of static networks while exploration of dynamic networks has been studied recently. In this

    更新日期:2020-11-12
  • A compositional view of derivations as interactive processes with applications to regulated and distributed rewriting
    Theor. Comput. Sci. (IF 0.747) Pub Date : 2020-11-09
    Paolo Bottoni; Anna Labella

    The derivation process in rewriting systems, especially in Chomskyan grammars, can be seen as consisting of four stages: (1) selection of the production to apply from a supply of productions available at that step, (2) check of applicability of the production, possibly on different matches, (3) selection of the match at which to apply the production, (4) actual application. In this paper, we explore

    更新日期:2020-11-09
  • Optimal run problem for weighted register automata
    Theor. Comput. Sci. (IF 0.747) Pub Date : 2020-11-06
    Hiroyuki Seki; Reo Yoshimura; Yoshiaki Takata

    Register automata (RA) are a computational model that can handle data values by adding registers to finite automata. Recently, weighted register automata (WRA) were proposed by extending RA so that weights can be specified for transitions. In this paper, we first investigate decidability and complexity of decision problems on the weights of runs in WRA. We then propose an algorithm for the optimal

    更新日期:2020-11-06
  • Computational complexity of the 2-connected Steiner network problem in the ℓp plane
    Theor. Comput. Sci. (IF 0.747) Pub Date : 2020-11-06
    C.J. Ras; M. Brazil; D.A. Thomas

    The geometric 2-connected Steiner network problem asks for a shortest bridgeless network spanning a given set of terminals in the plane such that the total length of all edges of the network, as measured in the ℓp metric, is a minimum. Using reduction from the problem of deciding the Hamiltonicity of planar cubic bipartite graphs we show that this problem is NP-hard (and NP-complete when discretised)

    更新日期:2020-11-06
  • The linear time-branching time spectrum of equivalences for stochastic systems with non-determinism
    Theor. Comput. Sci. (IF 0.747) Pub Date : 2020-11-06
    Arpit Sharma

    This paper studies the linear time-branching time spectrum of equivalences for a subclass of interactive Markov chains (IMCs) that are not subject to any further synchronization. This subclass of IMCs is known as closed IMCs. We define several variants of trace equivalence by performing button pushing experiments on stochastic trace machines. We establish the relation between these equivalences and

    更新日期:2020-11-06
  • Conditional diagnosability of Cayley graphs generated by wheel graphs under the PMC model
    Theor. Comput. Sci. (IF 0.747) Pub Date : 2020-11-05
    Yulong Wei; Min Xu

    Fault diagnosis of systems is an important area of study in the design and maintenance of multiprocessor systems. In 2005, Lai et al. [12] introduced conditional diagnosability under the assumption that all the neighbors of any processor in a multiprocessor system cannot be faulty at the same time. In this paper, we completely determine the conditional diagnosability of Cayley graphs generated by wheel

    更新日期:2020-11-06
  • Note on Rg-conditional diagnosability of hypercube
    Theor. Comput. Sci. (IF 0.747) Pub Date : 2020-11-05
    Yihong Wang; Cheng-Kuan Lin; Shuming Zhou

    The g-good-neighbor conditional diagnosability, which specifies at least g fault-free neighbors for each fault-free node, is a very important metric in system-level diagnosis. Recently, the g-good-neighbor conditional diagnosabilities of many networks have been investigated. To enhance the g-good-neighbor conditional diagnosability, the Rg-conditional diagnosability, which requires at least g fault-free

    更新日期:2020-11-06
  • Characterization of the lengths of binary circular words containing no squares other than 00, 11, and 0101
    Theor. Comput. Sci. (IF 0.747) Pub Date : 2020-11-05
    James D. Currie; Jesse T. Johnson

    We characterize exactly the lengths of binary circular words containing no squares other than 00, 11, and 0101.

    更新日期:2020-11-06
  • The h-restricted connectivity of the generalized hypercubes
    Theor. Comput. Sci. (IF 0.747) Pub Date : 2020-11-05
    Xiaowang Li; Shuming Zhou; Xia Guo; Tianlong Ma

    Connectivity is an important index in evaluating the reliability and fault tolerant ability of interconnection network. However the traditional connectivity is inappropriate for large scale multiprocessor systems. The h-restricted connectivity, as a generalization of traditional connectivity, was proposed to estimate the reliability of interconnection networks more accurately. For an interconnection

    更新日期:2020-11-06
  • Fixed-parameter tractable algorithms for Tracking Shortest Paths
    Theor. Comput. Sci. (IF 0.747) Pub Date : 2020-09-11
    Aritra Banik; Pratibha Choudhary; Venkatesh Raman; Saket Saurabh

    We consider the parameterized complexity of the problem of tracking shortest s-t paths in graphs, motivated by applications in security and wireless networks. Given an undirected and unweighted graph with a source s and a destination t, Tracking Shortest Paths asks if there exists a k-sized subset of vertices (referred to as tracking set) that intersects each shortest s-t path in a distinct set of

    更新日期:2020-10-30
  • Maximum independent sets in subcubic graphs: New results
    Theor. Comput. Sci. (IF 0.747) Pub Date : 2020-09-11
    A. Harutyunyan; M. Lampis; V. Lozin; J. Monnot

    The maximum independent set problem is known to be NP-hard in the class of subcubic graphs, i.e. graphs of vertex degree at most 3. We study complexity of the problem on hereditary subclasses of subcubic graphs. Each such subclass can be described by means of forbidden induced subgraphs. In case of finitely many forbidden induced subgraphs a necessary condition for polynomial-time solvability of the

    更新日期:2020-10-30
  • Simple and local independent set approximation
    Theor. Comput. Sci. (IF 0.747) Pub Date : 2020-09-14
    Ravi B. Boppana; Magnús M. Halldórsson; Dror Rawitz

    We study the worst-case behavior of Turán-like bounds for unweighted and weighted independent sets in bounded-degree graphs. In particular, we revisit a randomized approach of Boppana that forms a simple 1-round distributed algorithm, as well as a streaming algorithm and a preemptive online algorithm. We show that it gives a tight (Δ+1)/2-approximation in unweighted graphs of maximum degree Δ, which

    更新日期:2020-10-30
  • Fast two-robot disk evacuation with wireless communication
    Theor. Comput. Sci. (IF 0.747) Pub Date : 2020-09-14
    Ioannis Lamprou; Russell Martin; Sven Schewe

    In the fast evacuation problem, we study the path planning problem for two robots who want to minimize the worst-case evacuation time on the unit disk, that is, the time till both of them evacuate. The robots are initially placed at the center of the disk. In order to evacuate, they need to reach an unknown point, the exit, on the boundary of the disk. Once one of the robots finds the exit, it will

    更新日期:2020-10-30
  • A distributed algorithm for finding Hamiltonian cycles in random graphs in O(log⁡n) time
    Theor. Comput. Sci. (IF 0.747) Pub Date : 2020-09-14
    Volker Turau

    It is known for some time that a random graph G(n,p) contains w.h.p. a Hamiltonian cycle if p is larger than the critical value pcrit=(log⁡n+log⁡log⁡n+ωn)/n. The determination of a concrete Hamiltonian cycle for G(n,p) is a nontrivial task, even when p is much larger than pcrit. In this paper we consider random graphs G(n,p) with p in Ω˜(1/n), where Ω˜ hides poly-logarithmic factors in n. For this

    更新日期:2020-10-30
  • Fractional matching preclusion of product networks
    Theor. Comput. Sci. (IF 0.747) Pub Date : 2020-09-14
    Jinling Wang

    The matching preclusion number of a graph, introduced in [2] as a fault analysis, is the minimum number of edges whose deletion leaves a resulting graph that has neither perfect matchings nor almost perfect matchings. As a generalization, Liu and Liu [14] recently introduced the concept of fractional matching preclusion number. The fractional matching preclusion number of graph is the minimum number

    更新日期:2020-10-30
  • On caterpillar factors in graphs
    Theor. Comput. Sci. (IF 0.747) Pub Date : 2020-09-14
    Csilla Bujtás; Stanislav Jendroľ; Zsolt Tuza

    A caterpillar is either a K2 or a tree on at least 3 vertices such that deleting its leaves we obtain a path of order at least 1. Given a simple undirected graph G=(V,E), a caterpillar factor of G is a set of caterpillar subgraphs of G such that each vertex v∈V belongs to exactly one of them. A caterpillar factor F is internally even if every vertex of degree degF(v)≥2 has an even degree; F is odd

    更新日期:2020-10-30
  • Priority evacuation from a disk: The case of n ≥ 4
    Theor. Comput. Sci. (IF 0.747) Pub Date : 2020-09-15
    J. Czyzowicz; K. Georgiou; R. Killick; E. Kranakis; D. Krizanc; L. Narayanan; J. Opatrny; S. Shende

    We introduce and study a new search-type problem with (n+1)-robots on a disk. The searchers (robots) all start from the center of the disk, have unit speed, and can communicate wirelessly. The goal is for a distinguished robot (the queen) to reach and evacuate from an exit that is hidden on the perimeter of the disk in as little time as possible. The remaining n robots (servants) are there to facilitate

    更新日期:2020-10-30
  • Parameterized algorithms and kernels for almost induced matching
    Theor. Comput. Sci. (IF 0.747) Pub Date : 2020-09-15
    Mingyu Xiao; Shaowei Kou

    The Almost Induced Matching problem asks whether we can delete at most k vertices from the input graph such that each vertex in the remaining graph has a degree exactly one. This paper studies parameterized algorithms for this problem by taking the size k of the deletion set as the parameter. We give a 7k-vertex kernel and an O⁎(1.7485k)-time and polynomial-space algorithm, both of which are the best-known

    更新日期:2020-10-30
  • On the curve complexity of 3-colored point-set embeddings
    Theor. Comput. Sci. (IF 0.747) Pub Date : 2020-09-17
    Emilio Di Giacomo; Leszek Gąsieniec; Giuseppe Liotta; Alfredo Navarra

    We establish new results on the curve complexity of k-colored point-set embeddings when k=3. We show that there exist 3-colored caterpillars with only three independent edges whose 3-colored point-set embeddings may require Ω(n13) bends on Ω(n23) edges. This settles an open problem by Badent et al. [5] about the curve complexity of point set embeddings of k-colored trees and it extends a lower bound

    更新日期:2020-10-30
  • The untyped computational λ-calculus and its intersection type discipline
    Theor. Comput. Sci. (IF 0.747) Pub Date : 2020-09-17
    Ugo de'Liguoro; Riccardo Treglia

    We study a Curry style type assignment system for untyped λ-calculi with effects, based on Moggi's monadic approach. Moving from the abstract definition of monads, we introduce a version of the call-by-value computational λ-calculus based on Wadler's variant, without let, and with unit and bind operators. We define a notion of reduction for the calculus and prove it confluent. We then introduce an

    更新日期:2020-10-30
  • Prior-free multi-unit auctions with ordered bidders
    Theor. Comput. Sci. (IF 0.747) Pub Date : 2020-09-24
    Sayan Bhattacharya; Elias Koutsoupias; Janardhan Kulkarni; Stefano Leonardi; Tim Roughgarden; Xiaoming Xu

    Prior-free auctions are robust auctions that assume no distribution over bidders' valuations and provide worst-case (input-by-input) approximation guarantees. In contrast to previous work on this topic, we pursue good prior-free auctions with non-identical bidders. Prior-free auctions can approximate meaningful benchmarks for non-identical bidders only when sufficient qualitative information about

    更新日期:2020-10-30
  • Fault-Tolerant Complete Visibility for Asynchronous Robots with Lights Under One-Axis Agreement
    Theor. Comput. Sci. (IF 0.747) Pub Date : 2020-10-29
    Pavan Poudel; Aisha Aljohani; Gokarna Sharma

    We consider the distributed setting of N autonomous mobile robots that operate in Look-Compute-Move (LCM) cycles and communicate with other robots using colored lights following the robots with lights model. We assume obstructed visibility under which a robot cannot see another robot if a third robot is positioned between them on the straight line connecting them. We study the fundamental Complete

    更新日期:2020-10-30
  • On the longest common prefix of suffixes in an inverse Lyndon factorization and other properties
    Theor. Comput. Sci. (IF 0.747) Pub Date : 2020-10-29
    Paola Bonizzoni; Clelia De Felice; Rocco Zaccagnino; Rosalba Zizza

    The Lyndon factorization of a word has been largely studied and recently variants of it have been introduced and investigated with different motivations. In particular, the canonical inverse Lyndon factorization ICFL(w) of a word w, introduced in [1], maintains the main properties of the Lyndon factorization since it can be computed in linear time and it is uniquely determined. In this paper we investigate

    更新日期:2020-10-30
  • XML navigation and transformation by tree-walking automata and transducers with visible and invisible pebbles
    Theor. Comput. Sci. (IF 0.747) Pub Date : 2020-10-28
    Joost Engelfriet; Hendrik Jan Hoogeboom; Bart Samwel

    The pebble tree automaton and the pebble tree transducer are enhanced by additionally allowing an unbounded number of “invisible” pebbles (as opposed to the usual “visible” ones). The resulting pebble tree automata recognize the regular tree languages (i.e., can validate all generalized DTD's) and hence can find all matches of MSO definable patterns. Moreover, when viewed as a navigational device,

    更新日期:2020-10-30
  • Exploring the topological entropy of formal languages
    Theor. Comput. Sci. (IF 0.747) Pub Date : 2020-10-27
    Florian Starke

    We introduce the notions of topological entropy of a formal language and of a topological automaton. We show that the entropy function is surjective and bound the entropy of languages accepted by deterministic ε-free push-down automata with an arbitrary amount of stacks.

    更新日期:2020-10-30
  • Reliability and hybrid diagnosis of exchanged hypercube
    Theor. Comput. Sci. (IF 0.747) Pub Date : 2020-10-27
    Nianpeng Zhang; Qiang Zhu

    The exchanged hypercube, denoted by EH(s,t) where s,t≥1 are two positive integers, is a variant of hypercube network. The reliability and diagnosis capability of exchanged hypercubes have been investigated in this paper. First, we studied the h-extra connectivity and h-extra edge connectivity of EH(s,t) which can reflect its fault tolerance ability; Second, we studied the h-resticted vertex diagnosability

    更新日期:2020-10-30
  • Approximability of the Independent Feedback Vertex Set Problem for Bipartite Graphs
    Theor. Comput. Sci. (IF 0.747) Pub Date : 2020-10-26
    Yuma Tamura; Takehiro Ito; Xiao Zhou

    Given an undirected graph G with n vertices, the independent feedback vertex set problem is to find a vertex subset F of G with the minimum number of vertices such that F is both an independent set and a feedback vertex set of G, if it exists. This problem is known to be NP-hard for bipartite planar graphs of maximum degree four. In this paper, we study the approximability of the problem. We first

    更新日期:2020-10-30
  • On generalized highly potential words
    Theor. Comput. Sci. (IF 0.747) Pub Date : 2020-10-26
    Kristina Ago; Bojan Bašić; Stefan Hačko; Danijela Mitrović

    The number of palindromic factors of a given finite word is bounded above by its length increased by 1. The difference between this upper bound and the actual number of palindromic factors of a given word is called the palindromic defect (or only defect) of a given word (by definition, the defect is always nonnegative). Though the definition of defect fundamentally relies on finiteness of a given word

    更新日期:2020-10-30
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