On the complexity of H-coloring
Journal of Combinatorial Theory Series B
List homomorphisms to reflexive graphs
Journal of Combinatorial Theory Series B
Which problems have strongly exponential complexity?
Journal of Computer and System Sciences
Computational Complexity of Compaction to Reflexive Cycles
SIAM Journal on Computing
The Complexity of the Matching-Cut Problem
WG '01 Proceedings of the 27th International Workshop on Graph-Theoretic Concepts in Computer Science
The complexity of satisfiability problems
STOC '78 Proceedings of the tenth annual ACM symposium on Theory of computing
Compaction, Retraction, and Constraint Satisfaction
SIAM Journal on Computing
Journal of Computer and System Sciences
Linear time low tree-width partitions and algorithmic consequences
Proceedings of the thirty-eighth annual ACM symposium on Theory of computing
A complete complexity classification of the role assignment problem
Theoretical Computer Science - Graph colorings
Strong computational lower bounds via parameterized complexity
Journal of Computer and System Sciences
Grad and classes with bounded expansion I. Decompositions
European Journal of Combinatorics
Grad and classes with bounded expansion II. Algorithmic aspects
European Journal of Combinatorics
Grad and classes with bounded expansion III. Restricted graph homomorphism dualities
European Journal of Combinatorics
Bi-arc graphs and the complexity of list homomorphisms
Journal of Graph Theory
Covering graphs with few complete bipartite subgraphs
Theoretical Computer Science
SIAM Journal on Discrete Mathematics
Deciding First-Order Properties for Sparse Graphs
FOCS '10 Proceedings of the 2010 IEEE 51st Annual Symposium on Foundations of Computer Science
Algorithms for partition of some class of graphs under compaction
COCOON'11 Proceedings of the 17th annual international conference on Computing and combinatorics
The computational complexity of disconnected cut and 2K2-partition
CP'11 Proceedings of the 17th international conference on Principles and practice of constraint programming
The complexity of surjective homomorphism problems-a survey
Discrete Applied Mathematics
Locally constrained graph homomorphisms-structure, complexity, and applications
Computer Science Review
2K2-partition of some classes of graphs
Discrete Applied Mathematics
Parameterized Complexity
| Hi-index | 5.23 |
A homomorphism from a graph G to a graph H is a vertex mapping f:V"G-V"H such that f(u) and f(v) form an edge in H whenever u and v form an edge in G. The H-Coloring problem is that of testing whether a graph G allows a homomorphism to a given graph H. A well-known result of Hell and Nesetril determines the computational complexity of this problem for any fixed graph H. We study a natural variant of this problem, namely the SurjectiveH-Coloring problem, which is that of testing whether a graph G allows a homomorphism to a graph H that is (vertex-)surjective. We classify the computational complexity of this problem for when H is any fixed partially reflexive tree. Thus we identify the first class of target graphs H for which the computational complexity of SurjectiveH-Coloring can be determined. For the polynomial-time solvable cases we show a number of parameterized complexity results, including in particular ones on graph classes with (locally) bounded expansion.