For a fixed pattern graph H, let H-CONTRACTIBILITY denote the problem of decidingwhether a given input graph is contractible to H. We continue a line of research that wasstarted in 1987 by Brouwer & Veldman, and we determine the computational complexity ofH-CONTRACTIBILITY for certain classes of pattern graphs. In particular, we pin-pointthe complexity for all graphs H with five...

Information technology enabled exchanges in electronic markets have significant implications for buyer–supplier relaVivek Choudhury was the accepting senior editor for this paper. tionships. Building on studies that emphasize the role of intangible assets in interorganizational relationships, this study argues that buyers are less likely to use reverse auctions for supplier relationships involv...

The Induced Minor Containment problem takes as input two graphs G and H, and asks whether G has H as an induced minor. We show that this problem is fixed parameter tractable in |VH | if G belongs to any nontrivial minor-closed graph class and H is a planar graph. For a fixed graph H, the H-Contractibility problem is to decide whether a graph can be contracted to H. The computational complexity ...

For a fixed graph H, let H-CON denote the problem of determining whether a given graph is contractible to H. The complexity of H-CON is studied for H belonging to certain classes of graphs, together covering all connected graphs of order at most 4. In particular, H-CON is NP-complete if H is a connected triangle-free graph other than a star. For each connected graph H of order a t most 4 other ...