The two Igusa zeta function conjectures for degree five

Let KK be a local field of residue characteristic not dividing 5!5!. Let qq be the size of its residue field, set t=qst=q^{-s} and (a)=1qa(a)=1-q^{-a}, and define

I5(s)=1(1)(2)2(3)2(4)2(5)V5(OK)Δ5(v)s1dμV5(v).I_5(s)=\frac{1}{(1)(2)^2(3)^2(4)^2(5)}\int_{V_5(\mathcal{O}_K)}|\Delta_5(v)|^{s-1}d\mu_{V_5}(v).

The degree-five Igusa zeta function conjectures. The following two assertions are conjectured, with (b) stronger than (a): (a) I5(s)I_5(s) is a power series in qq and tt with positive integer coefficients independent of KK, and every nonzero term qatbq^at^b with b2b\geq2 satisfies a+1<ba+1<b; (b) I5(s)I_5(s) is a power series in qq and tt with positive integer coefficients independent of KK, and every nonzero term qatbq^at^b with b2b\geq2 satisfies 2a+1<b2a+1<b.

These properties would provide the Igusa zeta function input needed to extend the paper's density and smallness results to d=5d=5, and the first would imply smoothability results for reduced proper curves admitting degree-five maps to smooth curves. The relevant rationality question remains open in positive characteristic, so the conjectures are not established here.

Sources & referencesView supporting material

Primary source

Kevin Chang, “Hurwitz spaces, Nichols algebras, and Igusa zeta functions”, arXiv:2306.10446 (2024).

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