The sharp writhe conjecture for smoothly hard max-tb Legendrian unknots

From papers

Let minwrR2\mathrm{minwr}_{\mathbb{R}^2} and minwrS2\mathrm{minwr}_{S^2} denote the minimum writhe of a max-tb Legendrian unknot front projection that is smoothly hard on the plane and sphere, respectively. Sharp writhe conjecture. For smoothed max-tb Legendrian unknots,

minwrR2=3,minwrS2=4.\mathrm{minwr}_{\mathbb{R}^2}=3,\qquad \mathrm{minwr}_{S^2}=4.

This conjecture sharpens the bounds established in the paper, namely 2minwrR232\leq \mathrm{minwr}_{\mathbb{R}^2}\leq 3 and 2minwrS242\leq \mathrm{minwr}_{S^2}\leq 4, and would give a sharp writhe obstruction for smoothly spherically hard max-tb unknot fronts.

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Sources & referencesView supporting material

Primary source

Joseph Breen, Austin Christian and Angela Wu, “Hard Legendrian unknots”, arXiv:2604.27213 (2026).

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