The road coloring problem (RCP) originates in [1 ] and it was stated explicitly in the paper by Adler et al. [2]. It can be formulated as follows: let C be a strongly connected, constant out-degree finite digraph such...
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The road coloring problem (RCP) originates in [1 ] and it was stated explicitly in the paper by Adler et al. [2]. It can be formulated as follows: let C be a strongly connected, constant out-degree finite digraph such that the greatest common divisor (gcd) of the lengths of all cycles in C equals 1. Is there an edge labeling, turning C into a deterministic finite synchronizing automaton? The problem is of great importance in automata theory, because the synchronizing property makes the automaton behavior resistant to errors that could occur in an input word: after the error is detected, the synchronizing word can reset the automaton to its initial state, as if there were no error. In this way we regain the control over automaton action.
We consider the problem of labeling a directed multigraph so that it becomes a synchronized finite automaton, as an ultimate goal to solve the famous roadcoloring Conjecture, cf. [1,2]. We introduce a relabeling meth...
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We consider the problem of labeling a directed multigraph so that it becomes a synchronized finite automaton, as an ultimate goal to solve the famous roadcoloring Conjecture, cf. [1,2]. We introduce a relabeling method which can be used for a large class of automata to improve their 'degree of synchronization'. This allows, for example, to formulate the conjecture in several equivalent ways.
The synchronization problem is investigated for the class of locally strongly transitive automata introduced in Carpi and D'Alessandro (2009) [9]. Some extensions of this problem related to the notions of stable s...
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The synchronization problem is investigated for the class of locally strongly transitive automata introduced in Carpi and D'Alessandro (2009) [9]. Some extensions of this problem related to the notions of stable set and word of minimal rank of an automaton are studied. An application to synchronizing colorings of aperiodic graphs with a Hamiltonian path is also considered. (C) 2012 Elsevier Inc. All rights reserved.
The roadcoloring Theorem states that every aperiodic directed graph with constant outdegree has a synchronized coloring. This theorem had been conjectured during many years as the road coloring problem before being s...
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The roadcoloring Theorem states that every aperiodic directed graph with constant outdegree has a synchronized coloring. This theorem had been conjectured during many years as the road coloring problem before being settled by A. ***'s proof leads to an algorithm that finds a synchronized labeling with a cubic worst-case time complexity. We show a variant of his construction with a worst-case complexity which is quadratic in time and linear in space. We also extend the roadcoloring Theorem to the periodic case. (C) 2013 Elsevier B.V. All rights reserved.
First, we close the multi-parameter analysis of a canonical problem concerning short reset words (SYN) initiated by Fernau et al. (2013). Namely, we prove that the problem, parameterized by the number of states, does ...
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First, we close the multi-parameter analysis of a canonical problem concerning short reset words (SYN) initiated by Fernau et al. (2013). Namely, we prove that the problem, parameterized by the number of states, does not admit a polynomial kernel unless the polynomial hierarchy collapses. Second, we consider a related canonical problem concerning synchronizing roadcolorings (SRCP). Here we give a similar complete multi-parameter analysis. Namely, we show that the problem, parameterized by the number of states, admits a polynomial kernel and we close the previous research of restrictions to particular values of both the alphabet size and the maximum length of a reset word.
The parameterized Synchronizing-road-coloringproblem (in short: SRCPCl) in its decision version can be formulated as follows: given a digraph Gwith constant out-degree l, check if G can be synchronized by some word o...
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The parameterized Synchronizing-road-coloringproblem (in short: SRCPCl) in its decision version can be formulated as follows: given a digraph Gwith constant out-degree l, check if G can be synchronized by some word of length C for some synchronizing labeling. We consider the family {SRCPCl}(C, l) of problems parameterized with constants C and l and try to find for which C and l the problem SRCPCl is NP-complete. It is known that SRCPC3 is NP-complete for C >= 8. We improve this result by showing that it is so for C >= 4and for l >= 3. We also show that SRCPCl is in P for C <= 2and l >= 1. Finally, we solve the problem completely for the non-binary alphabets by showing that SRCP3l is in P for l >= 3. (C) 2015 Elsevier Inc. All rights reserved.
By the roadcoloring Theorem (Trahtman, 2008), the edges of any given aperiodic strongly connected directed multigraph with a constant out-degree can be colored such that the resulting automaton admits a reset word. T...
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By the roadcoloring Theorem (Trahtman, 2008), the edges of any given aperiodic strongly connected directed multigraph with a constant out-degree can be colored such that the resulting automaton admits a reset word. There may also be a need for a particular reset word to be admitted. In this paper we consider the following problem: given a word w and digraph G, is it true that G has a coloring that is synchronized by w? We show that it is NP-complete for certain fixed words. For the binary alphabet we present a classification that separates such words from those that make the problem solvable in polynomial time. The classification differs if we consider only strongly connected multigraphs. In this restricted setting the classification remains incomplete. (C) 2016 Elsevier Inc. All rights reserved.
An ergodic Markov chain is proved to be the realization of a random walk in a directed graph subject to a synchronizing roadcoloring. The result ensures the existence of appropriate random mappings in Propp-Wilson...
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An ergodic Markov chain is proved to be the realization of a random walk in a directed graph subject to a synchronizing roadcoloring. The result ensures the existence of appropriate random mappings in Propp-Wilson's coupling from the past. The proof is based on the roadcoloring theorem. A necessary and sufficient condition for approximate preservation of entropies is also given.
Cerny's conjecture asserts the existence of a synchronizing word of length at most (n - 1)(2) for any synchronized n-state deterministic automaton. We prove a quadratic upper bound on the length of a synchronizing...
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Cerny's conjecture asserts the existence of a synchronizing word of length at most (n - 1)(2) for any synchronized n-state deterministic automaton. We prove a quadratic upper bound on the length of a synchronizing word for any synchronized n-state deterministic automaton satisfying the following additional property: there is a letter a such that for any pair of states p, q, one has p.a(r) = q.a(s) for some integers r, s (for a state p and a word w, we denote by p.w the state reached from p by the path labeled w). As a consequence, we show that for any finite synchronized prefix code with an n-state decoder, there is a synchronizing word of length O(n(2)). This applies in particular to Huffman codes.
The synchronization problem is investigated for a new class of deterministic automata called locally strongly., transitive. An application to synchronizing colorings of aperiodic graphs with a cycle of prime length is...
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ISBN:
(纸本)9783642038150
The synchronization problem is investigated for a new class of deterministic automata called locally strongly., transitive. An application to synchronizing colorings of aperiodic graphs with a cycle of prime length is also considered.
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