This is a book about graph homomorphisms. Graph theory is now an established discipline
but the study of graph homomorphisms has only recently begun to gain wide acceptance …

Polymorphisms, and How to Use Them Page 1 Polymorphisms, and How to Use Them Libor Barto
∗1, Andrei Krokhin2, and Ross Willard †3 1 Department of Algebra, Faculty of Mathematics and …

Constraint satisfaction problems have enjoyed much attention since the early seventies, and
in the last decade have become also a focus of attention amongst theoreticians. Graph …

G, H, and lists, a list homomorphism of G to H with respect to the lists L is a map**, such
that for all, and for all. The list homomorphism problem for a fixed graph H asks whether or …

In a constraint satisfaction problem (CSP), the aim is to find an assignment of values to a
given set of variables, subject to specified constraints. The CSP is known to be NP-complete …

In a constraint satisfaction problem (CSP), the aim is to find an assignment of values to a
given set of variables, subject to specified constraints. The CSP is known to be NP-complete …

Given graphs G, H, and lists L (v)⊆ V (H), v ε V (G), a list homomorphism of G to H with
respect to the lists L is a map** f: V (G)→ V (H) such that uv ε E (G) implies f (u) f (v) ε E …

List partitions generalize list colorings and list homomorphisms.(We argue that they may be
called list" semihomomorphisms.") Each symmetric matrix M over 0, 1,* defines a list partition …

In recent years there has been an increased interest in algorithms that can perform frequent
pattern discovery in large databases of graph structured objects. While the frequent …

We prove that the complements of interval bigraphs are precisely those circular arc graphs
of clique covering number two, which admit a representation without two arcs covering the …