arXiv subjects

Peikai Qi

Publications and source records attributed to Peikai Qi.

5 recordsLinked to original sources

arXiv2026

Pseudonullity for fine Selmer groups over multiple $\mathbb{Z}_p^{d}$-extensions

In this article, we develop vertical control theorems for fine Selmer groups associated with Galois representations and their deformations in $p$-adic families. We apply them to provide new evidence for Conjectures A and B of Coates--Sujatha and to obtain pseudonullity of the fine Selmer groups for cyclotomic characters, elliptic curves, classical cuspidal newforms, and Hida families of $p$-ordinary cuspidal newforms.

math.NT↗

arXiv2024

On the Non p-Rationality and Iwasawa Invariants of Certain Real Quadratic Fields

Let $p$ be an odd prime, and $m,r \in \mathbb{Z}^+$ with $m$ coprime to $p$. In this paper we investigate the real quadratic fields $K = \mathbb{Q}(\sqrt{m^2p^{2r} + 1})$. We first show that for $m < C$, where constant $C$ depends on $p$, the fundamental unit $\varepsilon$ of $K$ satisfies the congruence $\varepsilon^{p-1} \equiv 1 \mod{p^2}$, which implies that $K$ is a non $p$-rational field. Varying $r$ then gives an infinite family of non $p$-rational fields. When $m = 1$ and $p$ is a non-Wieferich prime, we use a criterion of Fukuda and Komatsu to show that if $p$ does not divide the class number of $K$, then the Iwasawa invariants for cyclotomic $\mathbb{Z}_p$-extension of $K$ vanish. We conjecture that there are infinitely many $r$ such that $p$ does not divide the class number of $K$.

math.NT↗

arXiv2024

Iwasawa $λ$ invariant and Massey product

We compute Iwasawa $λ$ invariant in terms of Massey products in Galois cohomology with restricted ramification. When applied to imaginary quadratic fields and cyclotomic fields, we obtain a new proof and generalization of results of Gold and McCallum-Sharifi. The main tool is the generalized Bockstein map introduced by Lam-Liu-Sharifi-Wake-Wang.

math.NT↗

arXiv2023

Multivariate Fibonacci-like Polynomials and their Applications

The Fibonacci polynomials are defined recursively as $f_{n}(x)=xf_{n-1}(x)+f_{n-2}(x)$, where $f_0(x) = 0$ and $f_1(x)= 1$. We generalize these polynomials to an arbitrary number of variables with the $r$-Fibonacci polynomial. We extend several well-known results such as the explicit Binet formula and a Cassini-like identity, and use these to prove that the $r$-Fibonacci polynomials are irreducible over $\mathbb{C}$ for $n \geq r \geq 3$. Additionally, we derive an explicit sum formula and a generalized generating function. Using these results, we establish connections to ordinary Bell polynomials, exponential Bell polynomials, Fubini numbers, and integer and set partitions.

math.CO↗

arXiv2018

Universally uniformly continuous metric spaces

We answer the question: "on which metric spaces $(M,d)$ are all continuous functions uniformly continuous?" Our characterization theorem improves and generalizes a previous result due to Levine and Saunders, and in particular is applicable to metric spaces which are "infinite dimensional."

math.GN↗