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EJC
2008

Locally constrained graph homomorphisms and equitable partitions

8 years 2 months ago
Locally constrained graph homomorphisms and equitable partitions
We explore the connection between locally constrained graph homomorphisms and degree matrices arising from an equitable partition of a graph. We provide several equivalent characterizations of degree matrices. As a consequence we can efficiently check whether a given matrix M is a degree matrix of some graph and also compute the size of a smallest graph for which it is a degree matrix in polynomial time. We extend the well-known connection between degree refinement matrices of graphs and locally bijective graph homomorphisms to locally injective and locally surjective homomorphisms by showing that also these latter types of homomorphisms impose a quasiorder on degree abstracts of some of the results presented in this paper were presented at international conferences Mathematical Foundations of Computer Science 2005 and Graph-Theoretical Concepts in Computer Science 2005 and appeared in Lecture Notes in Computer Science 3618 (2005), pp. 340
Jirí Fiala, Daniël Paulusma, Jan Arne
Added 10 Dec 2010
Updated 10 Dec 2010
Type Journal
Year 2008
Where EJC
Authors Jirí Fiala, Daniël Paulusma, Jan Arne Telle
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