English

$p$-adic symplectic geometry of integrable systems and Weierstrass-Williamson theory II

Symplectic Geometry 2026-02-11 v1 Number Theory

Abstract

This paper is a sequel to arXiv:2501.14444, in which we shall give proofs of several results stated in arXiv:2501.14444 (Theorems D--L) which, for brevity and clarity, we postponed to this sequel paper. These results were the following: for any prime number pp, first we show that every 22-by-22 symmetric matrix with coefficients in Qp\mathbb{Q}_p can be reduced to a canonical form, and we give the exact numbers of families of normal forms with one parameter and of isolated normal forms, which depend on pp. Then we make the same analysis for 44-by-44 matrices. We also prove that, for higher size, the number of families of normal forms of matrices, even in the non-degenerate case, grows almost exponentially with the size. The paper can be read independently of arXiv:2501.14444 as we recall the statements of arXiv:2501.14444 that we shall prove here. The statements and proofs of the present paper are of an algebraic and arithmetical nature, and rely mainly on Galois theory of pp-adic extension fields.

Keywords

Cite

@article{arxiv.2602.09898,
  title  = {$p$-adic symplectic geometry of integrable systems and Weierstrass-Williamson theory II},
  author = {Luis Crespo and Álvaro Pelayo},
  journal= {arXiv preprint arXiv:2602.09898},
  year   = {2026}
}

Comments

62 Pages, 9 Figures. This paper is a sequel (part II), to arXiv:2501.14444 (part I). Part I contained classification statements concerning p-adic integrable systems and p-adic matrices. In Part I we gave proofs of all statements concerning p-adic integrable systems. In part II we provide proofs of all statements (which we repeat to be as self contained as possible) concerning p-adic matrices