Reputation: 1573
This paper solves the optimal path cover problem for block graphs or bipartite permutation graph. In the third line of its introduction it's written that optimal path cover problem is NP-Complete and has given reference to "Computer and intractability: a guide to the theory of NP-completeness by David S. Johnson, Michael R. Garey". But I couldn't find its proof in the book. If anyone knows how to prove NP-Completeness of this problem then share your solution.
Optimal path cover problem:
Given a graph G, find a minimum number of vertex disjoint paths which together cover all the vertices of the graph.
Upvotes: 0
Views: 490
Reputation: 64913
Considering the obvious decision variant (ie given k, is there a cover with k paths)
OPC(k=1) detects Hamiltonian paths, so clearly it's NP-hard.
It's also in NP because given the paths, checking whether they're disjoint and covering is easy.
Upvotes: 2