Rudolph's characterization conjecture for quasipositive ribbons

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Let D4(r)={(z,w)∈C2:(∣z∣2+∣w∣2)1/2≤r}D^4(r)=\{(z,w)\in\mathbb{C}^2:(|z|^2+|w|^2)^{1/2}\leq r\}. A smoothly embedded surface S⊂D4(r)S\subset D^4(r) is ribbon-embedded if ∂S=S∩∂D4(r)\partial S=S\cap\partial D^4(r) and the restriction of (∣z∣2+∣w∣2)(|z|^2+|w|^2) to SS is a Morse function with no local maxima on Int⁡S\operatorname{Int}S. If r′r' is a regular value with 0<r′<r0<r'<r, set S′=S∩D4(r′)S'=S\cap D^4(r'); a pair (S,S′)(S,S') obtained this way is a ribbon-embedded pair. A surface ambient isotopic to a ribbon-embedded surface is a ribbon, and a subsurface S′⊂SS'\subset S of a ribbon is a subribbon if (S,S′)(S,S') is ambient isotopic to a ribbon-embedded pair. For sufficiently small ε≠0\varepsilon\neq0, let T~n,n\widetilde T_{n,n} be any one of the mutually isotopic ribbon-embedded surfaces Γn(ε)∩D4(1)\Gamma_n(\varepsilon)\cap D^4(1), where

Γn(ε)={(z,w)∈C2:zn+wn=ε}.\Gamma_n(\varepsilon)=\{(z,w)\in\mathbb{C}^2:z^n+w^n=\varepsilon\}.

Rudolph's characterization conjecture. A ribbon is quasipositive if and only if, for some nn, it is ambient isotopic to a subribbon of T~n,n\widetilde T_{n,n}. This would characterize quasipositive ribbons through the standard complex plane-curve surfaces T~n,n\widetilde T_{n,n}; the source presents it as a conjectural generalization, and no resolution is supplied here.

References

Primary source

Lee Rudolph, “A characterization of quasipositive Seifert surfaces (Constructions of quasipositive knots and links, III)”, arXiv:math/0411320 (2004).

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