2013/05/07 by Jim Geelen, Geelen, Jim, Tony Huynh +3 · 1 citation
Computer Science · Mathematics · #Advanced Graph Theory Research #Complexity and Algorithms in Graphs #Computational Geometry and Mesh Generation #math.CO #msc:05C83
paper · pdf · doi:10.48550/arxiv.1305.1451
24 pages, 0 figures
arxiv created 2016/05/02 · arxiv updated 2016/05/03
Let Σ be a surface with boundary b(Σ), L be a collection of k disjoint b(Σ)-paths in Σ, and P be a non-separating b(Σ)-path in Σ. We prove that there is a homeomorphism ϕ: Σ→ Σ that fixes each point of b(Σ) and such that ϕ(L) meets P at most 2k times. With this theorem, we derive explicit constants in the graph minor algorithms of Robertson and Seymour. We reprove a result concerning redundant vertices for graphs on surfaces, but with explicit bounds. That is, we prove that there exists a computable integer t:=t(Σ,k) such that if v is a 't-protected' vertex in a surface Σ, then v is redundant with respect to any k-linkage.