Comb inequalities for typical Euclidean TSP instances
We prove that even in average case, the Euclidean Traveling Salesman Problem exhibits an integrality gap of (1+ϵ) for ϵ>0 when the Held-Karp Linear Programming relaxation is augmented by all comb inequalities of bounded size. This implies that large classes of branch-and-cut algorithms take exponential time for the Euclidean TSP, even on random inputs.
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