Four new upper bounds for the stability number of a graph
نویسنده
چکیده
In 1979, L. Lovász defined the theta number, a spectral/semidefinite upper bound on the stability number of a graph, which has several remarkable properties (for example, it is exact for perfect graphs). A variant, the inverse theta number, defined recently by the author in a previous work, also constitutes an upper bound on the stability number. In the paper we will describe counterparts of theorems due to Wilf and Hoffman, four spectral upper bounds on the stability number, which differ from both the theta and the inverse theta numbers.
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