We prove a theorem that bounds the Heegaard genus from below under special kinds of toroidal amalgamations of 3–manifolds. As a consequence, we conclude that t(K1 # K2) ≥ max{t(K1),t(K2)} for any pair of knots K1,K2 ⊂ S3, where t(K) denotes the tunnel number of K.
Keywords: tunnel number, knots, Heegaard splittings, connected sum
Schirmer, Trenton  1
@article{10_2140_agt_2016_16_1279,
author = {Schirmer, Trenton},
title = {A lower bound on tunnel number degeneration},
journal = {Algebraic and Geometric Topology},
pages = {1279--1308},
year = {2016},
volume = {16},
number = {3},
doi = {10.2140/agt.2016.16.1279},
url = {http://geodesic.mathdoc.fr/articles/10.2140/agt.2016.16.1279/}
}
Schirmer, Trenton. A lower bound on tunnel number degeneration. Algebraic and Geometric Topology, Tome 16 (2016) no. 3, pp. 1279-1308. doi: 10.2140/agt.2016.16.1279
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