Genus 9 and 11 minimal stretch factor conjecture for nonorientable surfaces

Let NgN_g be the closed nonorientable surface of genus gg, and let δ+(Ng)\delta^+(N_g) be the minimal stretch factor among pseudo-Anosov homeomorphisms of NgN_g with an orientable invariant foliation. The singularity type records the prong numbers of the singularities of a minimizing pseudo-Anosov map.

Genus 9 and 11 minimal stretch factor conjecture. The minimal stretch factors and minimal polynomials are predicted to be

gδ+(Ng)Minimal polynomial of δ+(Ng)singularity type91.35680x8x5x4x31(16)111.22262x12x7x6x51x2+x+1(8,8,8)\begin{array}{c|c|c|c} g & \delta^+(N_g)\approx & \text{Minimal polynomial of }\delta^+(N_g) & \text{singularity type}\\ \hline 9 & 1.35680 & x^8-x^5-x^4-x^3-1 & (16)\\ 11 & 1.22262 & \dfrac{x^{12}-x^7-x^6-x^5-1}{x^2+x+1} & (8,8,8) \end{array}

These predictions concern the cases not settled by the paper's elimination tests: the authors state that the remaining candidate polynomials should be eliminable and that their constructed examples should be minimal. The conjecture is open in the source.

Sources & referencesView supporting material

Primary source

Livio Liechti and Balázs Strenner, “Minimal pseudo-Anosov stretch factors on nonoriented surfaces”, arXiv:1806.00033 (2020).

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