Convolution, cumulants and infinitesimal generators in the formal power series ring

Fuente: arXiv
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Main Authors: Tsujie, Shuhei, Ueda, Yuki
Format: Preprint
Published: 2026
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author Tsujie, Shuhei
Ueda, Yuki
author_facet Tsujie, Shuhei
Ueda, Yuki
contents We extend the notions of finite free convolution and finite free cumulants to the setting of formal power series by introducing their natural analogues, namely $t$-deformed convolution and $t$-deformed cumulants. In this framework, we establish $t$-deformed analogues of the law of large numbers and the central limit theorem, revealing structural parallels with classical, free, and finite free probability theories. We show that the case $t=-1$ recovers classical convolution at the level of moment generating functions, thereby connecting the theory directly to classical probability. We further investigate the infinitesimal generators associated with $\boxplus^t$-continuous semigroups, deriving explicit representation formulas that clarify how these generators describe the infinitesimal evolution of the semigroup. In the case $t = d$, our results yield explicit formulas for finite free infinitesimal generators. In the case $t = -1$, we relate these generators to those of one-dimensional Lévy processes by identifying the corresponding terms in their representations. This establishes a direct connection between $\boxplus^t$-convolution semigroups and classical Lévy-Khintchine-type generators.
format Preprint
id arxiv_https___arxiv_org_abs_2604_13819
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Convolution, cumulants and infinitesimal generators in the formal power series ring
Tsujie, Shuhei
Ueda, Yuki
Probability
Combinatorics
Operator Algebras
46L54, 13F25, 33C20, 47B48, 47D03, 60F05
We extend the notions of finite free convolution and finite free cumulants to the setting of formal power series by introducing their natural analogues, namely $t$-deformed convolution and $t$-deformed cumulants. In this framework, we establish $t$-deformed analogues of the law of large numbers and the central limit theorem, revealing structural parallels with classical, free, and finite free probability theories. We show that the case $t=-1$ recovers classical convolution at the level of moment generating functions, thereby connecting the theory directly to classical probability. We further investigate the infinitesimal generators associated with $\boxplus^t$-continuous semigroups, deriving explicit representation formulas that clarify how these generators describe the infinitesimal evolution of the semigroup. In the case $t = d$, our results yield explicit formulas for finite free infinitesimal generators. In the case $t = -1$, we relate these generators to those of one-dimensional Lévy processes by identifying the corresponding terms in their representations. This establishes a direct connection between $\boxplus^t$-convolution semigroups and classical Lévy-Khintchine-type generators.
title Convolution, cumulants and infinitesimal generators in the formal power series ring
topic Probability
Combinatorics
Operator Algebras
46L54, 13F25, 33C20, 47B48, 47D03, 60F05
url https://arxiv.org/abs/2604.13819