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prime-degree-plane

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Revision 276 · 2026-09-30 05:09 UTC
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“Written for the atlas by Claude Opus 5.5 at the direction of Danielle Fong (content/wiki/Statement__prime-degree-plane.md).”

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+---
+title: No plane Keller map has prime field degree
+short: [ℂ(x,y) : ℂ(p,q)] is never prime for a Keller map (unrefereed)
+kind: theorem
+status: proved
+tier: V4
+year: 2024
+authors: Vered Moskowicz
+statement: If $p,q\in\mathbb C[x,y]$ have constant nonzero Jacobian, then $[\mathbb C(x,y):\mathbb C(p,q)]$ is not a prime number.
+---
+Moskowicz's preprint proves that [[special-case-of::Statement:jc-plane|the plane conjecture holds for every Keller map whose field extension has prime degree]].<ref>V. Moskowicz, [There are no Keller maps having prime degree field extensions](https://arxiv.org/abs/2407.13795), arXiv:2407.13795 (16 July 2024; one version, eight pages, no journal reference).</ref> The proof splits on whether $xy$ lies in $\mathbb C(p,q)$. In one case every monomial generates the extension, which forces degree 2. In the other, restriction to a line gives injectivity. The argument ends by forcing degree 1 or 2. It then applies [[uses::Statement:keller-birational|Keller's birational theorem, which closes degree 1]]. For degree 2 it uses [[uses::Statement:campbell-galois|the Galois criterion, which closes degree 2 because a quadratic extension is Galois]], invoked through Bass–Connell–Wright's Theorem 2.12.
 
+The atlas marks this V4, as a claim. It is one unrefereed preprint, and the research found no independent check or published critique. The refereed record in the plane excludes degrees 3 and 4 (Orevkov; Domrina), and every degree up to 5 (Żołądek).
+ 
+In three dimensions the obstruction fails: [[Statement:gallagher-families|Gallagher's family]] realizes every prime from 3. This result bounds the field degree, which is a different quantity from the component degrees in the [[Statement:plane-gcd-bounds|gcd constraints]].
+ 
+<references />
+ 

Revision 276 as rendered

Moskowicz's preprint proves that the plane conjecture holds for every Keller map whose field extension has prime degree.[1] The proof splits on whether xyxy lies in C(p,q)\mathbb C(p,q). In one case every monomial generates the extension, which forces degree 2. In the other, restriction to a line gives injectivity. The argument ends by forcing degree 1 or 2. It then applies Keller's birational theorem, which closes degree 1. For degree 2 it uses the Galois criterion, which closes degree 2 because a quadratic extension is Galois, invoked through Bass–Connell–Wright's Theorem 2.12.

The atlas marks this V4, as a claim. It is one unrefereed preprint, and the research found no independent check or published critique. The refereed record in the plane excludes degrees 3 and 4 (Orevkov; Domrina), and every degree up to 5 (Żołądek).

In three dimensions the obstruction fails: Gallagher's family realizes every prime from 3. This result bounds the field degree, which is a different quantity from the component degrees in the gcd constraints.

  1. ↑ V. Moskowicz, There are no Keller maps having prime degree field extensions, arXiv:2407.13795 (16 July 2024; one version, eight pages, no journal reference).