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arXiv · 2609.21968

Improved bounds for universal convex covers of unit arcs

Ethan Keller
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Abstract

Moser's worm problem asks for a planar region of least area containing a congruent copy of every unit arc. We show that the infimum area $α$ among convex universal covers satisfies $0.239\leα\le0.24633\ldots$, reducing the gap between the previous refereed bounds by over $75\%$. For the lower bound, we choose four unit polygonal arcs and prove by finite subdivision that, however they are placed, their convex hull has area at least $0.239$. For the upper bound, we construct a quadrilateral of area $0.24633\ldots$ and prove cover universality by showing that its support inequalities force uncovered arcs to have length greater than one. The full proof is formalized in Lean 4 and verified by the Lean kernel. Code and certificates are available at https://github.com/ethan-keller/moser-worm-improved-bounds.

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Ethan Keller. 2026-09-18. Improved bounds for universal convex covers of unit arcs. https://arxiv.org/abs/2609.21968

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