Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
6424422 | European Journal of Combinatorics | 2011 | 7 Pages |
Abstract
The k-independence number of G, denoted as αk(G), is the size of a largest k-colorable subgraph of G. The direct product of graphs G and H, denoted as GÃH, is the graph with vertex set V(G)ÃV(H), where two vertices (x1,y1) and (x2,y2) are adjacent in GÃH, if x1 is adjacent to x2 in G and y1 is adjacent to y2 in H. We conjecture that for any graphs G and H, αk(GÃH)â¤Î±k(G)|V(H)|+αk(H)|V(G)|âαk(G)αk(H). The conjecture is stronger than Hedetniemi's conjecture. We prove the conjecture for k=1,2 and prove that αk(GÃH)â¤Î±k(G)|V(H)|+αk(H)|V(G)|âαk(G)α(H) holds for any k.
Related Topics
Physical Sciences and Engineering
Mathematics
Discrete Mathematics and Combinatorics
Authors
Simon Å pacapan,