On 4 - γt - Critical Graphs of Order 4 + Δ ( G )
نویسندگان
چکیده
A graph G with no isolated vertex is total domination vertex critical if for any vertex v of G that is not adjacent to a vertex of degree one, the total domination number of G− v is less than the total domination number of G. We call these graphs total domination critical or just γt-critical. If such a graph G has total domination number k, we call it k-γt-critical. We study an open problem of k-γt-critical graphs and obtain some results on the characterization of total domination critical graphs of order Δ(G) + 4. Mathematics Subject Classification: 05C69
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