Publications

Abstract : Abstract: In a digraph $ D=(X, mathcal {U}) $, not necessarily finite, an arc $(x, y) in mathcal {U} $ is reachable from a vertex $ u $ if there exists a directed walk $ W $ that originates from $ u $ and contains $(x, y) $. A subset $ S subseteq X $ is an arc-reaching set of $ D $ if for every arc $(x, y) $ there exists a diwalk $ W $ originating at a vertex $ u in S $ and containing $(x, y) $. A minimal arc-reaching set is an arc-basis. $ S $ is a point-reaching set if for every vertex $ v $ there exists a diwalk $ W $ to $ v $ riginating at a vertex $ u in S $