Knot exteriors with additive Heegaard genus and Morimoto's Conjecture

Tsuyoshi Kobayashi; Yo'av Rieck

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arXiv · math/0701765

Knot exteriors with additive Heegaard genus and Morimoto's Conjecture

Tsuyoshi Kobayashi·Yo'av Rieck

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Abstract

Given integers g_i > 1 (i=1,...,n) we prove that there exist infinitely may knots K_i in S^3 so that g(E(K_i)) = g_i and the Heegaard genus of the exterior of the connected sum of K_1,...,K_n is the sum the Heegaard genera of K_1,...,K_n, that is: g(E(K_1#...#K_n)) = g(E(K_1)) +...+ g(E(K_n)). (Here, E() denotes the exterior and g() the Heegaard genus.) Together with Theorem 1.5 of [1], this proves the existence of counterexamples to Morimoto's Conjecture (Conjecture 1.5 of [2]). [1] Tsuyoshi Kobayashi and Yo'av Rieck. On the growth rate of the tunnel number of knots. J. Reine Angew. Math., 592:63--78, 2006. [2] Kanji Morimoto. On the super additivity of tunnel number of knots.Math. Ann., 317(3):489--508, 2000.

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Tsuyoshi Kobayashi, Yo'av Rieck. 2007-01-28. Knot exteriors with additive Heegaard genus and Morimoto's Conjecture. https://arxiv.org/abs/math/0701765

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