Additivity of Heegaard genera under annulus sum
UDC 515.162 Let $M$ be a compact 3-manifold containing an essential annulus $A$ separating $M$ into two manifolds $M_1$ and $M_2.$ We prove that if, for each $i=1,2,$ $g(M_i) \geq 2$ and $M_i$ admits a Heegaard splitting with Heegaard distance not smaller than $2\bigl(g(M_1) + g(M_2)\bigr) - 1,$ t...
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| Дата: | 2026 |
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| Автори: | , , |
| Формат: | Стаття |
| Мова: | Англійська |
| Опубліковано: |
Institute of Mathematics, NAS of Ukraine
2026
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| Онлайн доступ: | https://umj.imath.kiev.ua/index.php/umj/article/view/9572 |
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| Назва журналу: | Ukrains’kyi Matematychnyi Zhurnal |
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Ukrains’kyi Matematychnyi Zhurnal| Резюме: | UDC 515.162
Let $M$ be a compact 3-manifold containing an essential annulus $A$ separating $M$ into two manifolds $M_1$ and $M_2.$ We prove that if, for each $i=1,2,$ $g(M_i) \geq 2$ and $M_i$ admits a Heegaard splitting with Heegaard distance not smaller than $2\bigl(g(M_1) + g(M_2)\bigr) - 1,$ then $g(M) = g(M_1) + g(M_2).$ As a corollary, we present a sufficient condition for the superadditivity of the tunnel number of knots under connected sum. |
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| DOI: | 10.3842/umzh.v78i7-8.9572 |