摘要
A defensive (offensive) k-alliance in F = (V, E) is a set S C V such that every v in S (in the boundary of S) has at least k more neighbors in S than it has in V / S. A set X C_ V is defensive (offensive) k-alliance free, if for all defensive (offensive) k-alliance S, S/ X ≠ 0, i.e., X does not contain any defensive (offensive) k-alliance as a subset. A set Y C V is a defensive (offensive) k-alliance cover, if for all defensive (offensive) k-alliance S, S ∩ Y ≠ 0, i.e., Y contains at least one vertex from each defensive (offensive) k-alliance of F. In this paper we show several mathematical properties of defensive (offensive) k-alliance free sets and defensive (offensive) k-alliance cover sets, including tight bounds on their cardinality.
A defensive (offensive) k-alliance in F = (V, E) is a set S C V such that every v in S (in the boundary of S) has at least k more neighbors in S than it has in V / S. A set X C_ V is defensive (offensive) k-alliance free, if for all defensive (offensive) k-alliance S, S/ X ≠ 0, i.e., X does not contain any defensive (offensive) k-alliance as a subset. A set Y C V is a defensive (offensive) k-alliance cover, if for all defensive (offensive) k-alliance S, S ∩ Y ≠ 0, i.e., Y contains at least one vertex from each defensive (offensive) k-alliance of F. In this paper we show several mathematical properties of defensive (offensive) k-alliance free sets and defensive (offensive) k-alliance cover sets, including tight bounds on their cardinality.