Length minimization of filling pairs on hyperbolic surfaces

Ni An; Bhola Nath Saha; Bidyut Sanki

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arXiv · 2601.15524

Length minimization of filling pairs on hyperbolic surfaces

Ni An·Bhola Nath Saha·Bidyut Sanki

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Abstract

A filling pair $(\alpha, \beta)$ of a surface $S_g$ is a pair of simple closed curves in minimal position such that the complement of $\alpha\cup\beta$ in $S_g$ is a disjoint union of topological disks. A filling pair is said to be minimally intersecting if the number of intersections between them, or equivalently, the number of complementary disks, is minimal among all filling pairs of $S_g$. For surfaces of genus $g \geq 3$, minimal filling pairs are well understood, whereas in genus two, such a pair divides the surface into exactly two disks. In this paper, we classify all minimal filling pairs up to the action of the mapping class group in genus two and determine the length of the shortest minimal filling pair.

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Ni An, Bhola Nath Saha, Bidyut Sanki. 2026-01-21. Length minimization of filling pairs on hyperbolic surfaces. https://arxiv.org/abs/2601.15524

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