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The Homomorphism Problem for the Free Monoid
, 2001
"... It is proved to be decidable, for any given nite subset F of X and mapping ' : F ! X , whether or not ' can be extended to an (injective) monoid homomorphism ' : F ! X . As a corollary, the isomorphism problem for the free monoid is also solved: for any given nite subset ..."
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It is proved to be decidable, for any given nite subset F of X and mapping ' : F ! X , whether or not ' can be extended to an (injective) monoid homomorphism ' : F ! X . As a corollary, the isomorphism problem for the free monoid is also solved: for any given nite
Lower Bounds for the Graph Homomorphism Problem?
"... Abstract. The graph homomorphism problem (HOM) asks whether the vertices of a given nvertex graph G can be mapped to the vertices of a given hvertex graph H such that each edge of G is mapped to an edge of H. The problem generalizes the graph coloring problem and at the same time can be viewed as ..."
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Cited by 1 (1 self)
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Abstract. The graph homomorphism problem (HOM) asks whether the vertices of a given nvertex graph G can be mapped to the vertices of a given hvertex graph H such that each edge of G is mapped to an edge of H. The problem generalizes the graph coloring problem and at the same time can be viewed
THE COMPLEXITY OF THE LIST HOMOMORPHISM PROBLEM FOR GRAPHS
, 2010
"... We completely classify the computational complexity of the list Hcolouring problem for graphs (with possible loops) in combinatorial and algebraic terms: for every graph H the problem is either NPcomplete, NLcomplete, Lcomplete or is firstorder definable; descriptive complexity equivalents ar ..."
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Cited by 9 (2 self)
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We completely classify the computational complexity of the list Hcolouring problem for graphs (with possible loops) in combinatorial and algebraic terms: for every graph H the problem is either NPcomplete, NLcomplete, Lcomplete or is firstorder definable; descriptive complexity equivalents
Approximation algorithms for graph homomorphism problems
 In Proceedings of Approximation Algorithms for Combinatorial Optimization (APPROX
, 2006
"... Abstract. We introduce the maximum graph homomorphism (MGH) problem: given a graph G, and a target graph H, find a mapping ϕ: VG ↦ → VH that maximizes the number of edges of G that are mapped to edges of H. This problem encodes various fundamental NPhard problems including Maxcut and Maxkcut. We ..."
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Cited by 7 (0 self)
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Abstract. We introduce the maximum graph homomorphism (MGH) problem: given a graph G, and a target graph H, find a mapping ϕ: VG ↦ → VH that maximizes the number of edges of G that are mapped to edges of H. This problem encodes various fundamental NPhard problems including Maxcut and Maxkcut. We
Extensions of the Minimum Cost Homomorphism Problem
 In Proceedings of the 16th International Computing and Combinatorics Conference (COCOON’10), volume 6196 of Lecture
"... ar ..."
THE COMPLEXITY OF THE LIST HOMOMORPHISM PROBLEM FOR GRAPHS
"... Abstract. We completely classify the computational complexity of the list Hcolouring problem for graphs (with possible loops) in combinatorial and algebraic terms: for every graph H the problem is either NPcomplete, NLcomplete, Lcomplete or is firstorder definable; descriptive complexity equiv ..."
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Abstract. We completely classify the computational complexity of the list Hcolouring problem for graphs (with possible loops) in combinatorial and algebraic terms: for every graph H the problem is either NPcomplete, NLcomplete, Lcomplete or is firstorder definable; descriptive complexity
Approximation Algorithms for Graph Homomorphism Problems
"... 2 + "0 \Delta approximation algorithm, for any constant "0? 0, implies an algorithm for distinguishing between certain averagecase instances of the subgraph isomorphism problem that appear to be hard. Complementing this, we give a \Gamma 1 2 + \Omega ( 1 jHj log jHj) ..."
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2 + "0 \Delta approximation algorithm, for any constant "0? 0, implies an algorithm for distinguishing between certain averagecase instances of the subgraph isomorphism problem that appear to be hard. Complementing this, we give a \Gamma 1 2 + \Omega ( 1 jHj log jHj)
The Complexity of Surjective Homomorphism Problems – a Survey
"... We survey known results about the complexity of surjective homomorphism problems, studied in the context of related problems in the literature such as list homomorphism, retraction and compaction. In comparison with these problems, surjective homomorphism problems seem to be harder to classify an ..."
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We survey known results about the complexity of surjective homomorphism problems, studied in the context of related problems in the literature such as list homomorphism, retraction and compaction. In comparison with these problems, surjective homomorphism problems seem to be harder to classify
On the Complexity of Homomorphism Problems Involving Unary Functions
"... We show that the uniform constraint satisfaction problem where instances consist of pairs of unary functions (and an instance is a yesinstance if there is a homomorphism from the rst function to the second function) can be solved in logspace. We also show that any analogous nonuniform problem is L ..."
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We show that the uniform constraint satisfaction problem where instances consist of pairs of unary functions (and an instance is a yesinstance if there is a homomorphism from the rst function to the second function) can be solved in logspace. We also show that any analogous nonuniform problem
Results 1  10
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