List homomorphisms and circular arc graphs
The list homomorphism problem for a graph \(H\) has as input a graph \(G\) and lists \(L(v)\subseteq V(H)\) for the vertices \(v\in V(G)\). The output is a homomorphism \(f:G\to H\) with \(f(v)\in L(v)\) for every \(v\in V(G)\). It is shown that if \(H\) is loopless then this problem is polynomially solvable if \(\overline{H}\) is a circular arc graph of clique covering number 2, otherwise it is NP-complete. A new characterization is given for the former case.
scientific article; zbMATH DE number 1446786