Minimum Cost Homomorphisms to Locally Semicomplete and Quasi-Transitive Digraphs

Arvind Gupta Gregory Gutin Mehdi Karimi Eun Jung Kim Arash Rafiey Minimum Cost Homomorphisms to Locally Semicomplete and Quasi-Transitive Digraphs http://arxiv.org/abs/0712.0804 2007 CoRR abs/0712.0804 db/journals/corr/corr0712.html#abs-0712-0804 informal publication