19th Annual IEEE Symposium on Logic in Computer Science (LICS'04)
First-Order Definable Retraction Problems for Posets and Reflexive Graphs
Turku, Finland
July 13-July 17
ISBN: 0-7695-2192-4
A retraction from a structure P to its substructure Q is a homomorphism from P onto Q that is the identity on Q. We present an algebraic condition which completely characterises all posets and all reflexive graphs Q with the following property: the class of all posets or reflexive graphs, respectively, that admit a retraction onto Q is first-order definable.
Citation:
V?ctor Dalmau, Andrei Krokhin, Benoit Larose, "First-Order Definable Retraction Problems for Posets and Reflexive Graphs," lics, pp.232-241, 19th Annual IEEE Symposium on Logic in Computer Science (LICS'04), 2004