Graphs with chromatic number close to maximum degree
نویسندگان
چکیده
Let G be a color-critical graph with χ(G) ≥ Δ(G) = 2t + 1 ≥ 5 such that the subgraph of G induced by the vertices of degree 2t+1 has clique number at most t−1. We prove that then either t ≥ 3 and G = K2t+2 or t = 2 and G ∈ {K6, O5}, where O5 is a special graph with χ(O5) = 5 and |O5| = 9. This result for t ≥ 3 improves a case of a theorem by Rabern [9] and for t = 2 answers a question raised by Kierstead and Kostochka in [6]. AMS Subject Classification: 05C15
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ورودعنوان ژورنال:
- Discrete Mathematics
دوره 312 شماره
صفحات -
تاریخ انتشار 2012