MIHAI TALMACIU Department of Mathematics, Informatics and Education Sciences, Faculty of Sciences, "Vasile Alecsandri" University of Bacău, 157 Calea Mărăşeşti, 600115 Bacău, ROMANIA,
e-mail: mtalmaciu@ub.ro, mihaitalmaciu@yahoo.com
In this article we give a characterization of Pâ‚„-tidy graphs. We also give recognition algorithm for Pâ‚„-tidy graphs, comparable to existent ones as execution time. Finally, we determine the combinatorial optimization number in efficient time for Pâ‚„-tidy graphs. We show that for P4-tidy graphs clique problem is polynomial time.