STAMM@DBNINF5.BITNET (Hermann Stamm) (09/27/90)
I am interested in the following problem, whose complexity I am not able to determine ( is it in P or is it NP-hard ? ) : NEGATIVE-DIRECTED-SIMPLE-PATH (NDSP) Instance: Digraph D=(V,A) with arc-weights w:A-->{-1,0,+1} , vertices s,t \in V . Question: Exists a simple directed path from s leading to t with negative total weight ? Remarks: 1) Negative directed cycles in D are allowed ! 2) The path need not to be the most negative one ! ( Otherwise DHP \alpha NDSP ) 3) If arc-weights are w:{-1,0,1,2,...,|V|}, then DHP \alpha NDSP ! ( w(a):=|V|-2 iff a=(s,v) \in A and v \in V ) ( w(a):=-1 otherwise ) Thanks in advance , Hermann Stamm Universitaet Bonn STAMM@DBNINF5.BITNET