Free Meixner states

The Non-Commutative Cycle Lemma

We present a non-commutative version of the cycle lemma of Dvoretsky and Motzkin that applies to free groups and use this result to solve a number of problems involving cyclic reduction in the free group. We also describe an application to random matrices, in particular the fluctuations of Kesten's Law.

Product formulas on posets, Wick products, and a correction for the $q$-Poisson process

We give an example showing that the product and linearization formulas for the Wick product versions of the $q$-Charlier polynomials in (Anshelevich 2004) are incorrect. Next, we observe that the relation between monomials and several families of Wick polynomials is governed by "incomplete" versions of familiar posets. We compute Möbius functions for these posets, and prove a general poset product formula. These provide new proofs and new inversion and product formulas for Wick product versions of Hermite, Chebyshev, Charlier, free Charlier, and Laguerre polynomials. By different methods, we p…

Almost Commutative Probability Theory

We solve two longstanding major problems in Free Probability. This is achieved by generalising the theory to one with values in arbitrary commutative algebras. We prove the existence of the multi-variable $S$-transform, and show that it is naturally realised as a faithful linear representation. Further, we prove that in dimension one, the analog of the classical relation between addition and multiplication of independent random variables holds for free random variables, if the co-domain is an algebra over the rationals. In this case the multiplicative problem can be reduced to the additive one…

Commutative Moufang loops and alternative algebras

We compute the orders of free commutative Moufand loops of exponent 3 with $n\leq 7$ free generators and find embeddings of such loops into a loop of invertible elements of the free commutative alternative algebra with identity $x^3=0$.

Relations between infinitesimal non-commutative cumulants

Boolean, free and monotone cumulants as well as relations among them, have proven to be important in the study of non-commutative probability theory. Quite notably, Boolean cumulants were successfully used to study free infinite divisibility via the Boolean Bercovici--Pata bijection. On the other hand, in recent years the concept of infinitesimal non-commutative probability has been developed, together with the notion of infinitesimal cumulants which can be useful in the context of combinatorial questions. In this paper, we show that the known relations among free, Boolean and monotone cumulan…

The Hopf algebras of symmetric functions and quasisymmetric functions in non-commutative variables are free and cofree

We uncover the structure of the space of symmetric functions in non-commutative variables by showing that the underlined Hopf algebra is both free and co-free. We also introduce the Hopf algebra of quasi-symmetric functions in non-commutative variables and define the product and coproduct on the monomial basis of this space and show that this Hopf algebra is free and cofree. In the process of looking for bases which generate the space we define orders on the set partitions and set compositions which allow us to define bases which have simple and natural rules for the product of basis elements.

Transitive factorizations of free partially commutative monoids and Lie algebras

Let $\M(A,θ)$ be a free partially commutative monoid. We give here a necessary and sufficient condition on a subalphabet $B\subset A$ such that the right factor of a bisection $\M(A,θ)=\M(B,θ\_B).T$ be also partially commutative free. This extends strictly the (classical) elimination theory on partial commutations and allows to construct new factorizations of $\M(A,θ)$ and associated bases of $L\_K(A,θ)$.

Structure theorems of mixable shuffle algebras and free commutative Rota-Baxter algebras

We study the ring theoretical structures of mixable shuffle algebras and their associated free commutative Rota-Baxter algebras. For this study we utilize the connection of the mixable shuffle algebras with the overlapping shuffle algebra of Hazewinkel, quasi-shuffle algebras of Hoffman and quasi-symmetric functions. This connection allows us to apply methods and results on shuffle products and Lyndon words on ordered sets. As a result, we obtain structure theorems for a large class of mixable shuffle algebras and free commutative Rota-Baxter algebras with various coefficient rings.

同伦类型论中的自由交换幺半群

Free Commutative Monoids in Homotopy Type Theory

本文在同伦类型论中构造性地研究有限多重集，将其定义为自由交换幺半群，证明其两种代数表示的泛性质，并应用于经典线性逻辑的关系模型，最终给出相等类型刻画和列表商的新表示。

自由交换幺半群的理想扩张

Ideal extensions of free commutative monoids

本文引入间隙吸收幺半群，证明其链次度至多四且长度集为区间，并给出理想扩张的ω-素性界及有限间隙的等价条件。

Cumulants, free cumulants and half-shuffles

Free cumulants were introduced as the proper analog of classical cumulants in the theory of free probability. There is a mix of similarities and differences, when one considers the two families of cumulants. Whereas the combinatorics of classical cumulants is well expressed in terms of set partitions, the one of free cumulants is described, and often introduced in terms of non-crossing set partitions. The formal series approach to classical and free cumulants also largely differ. It is the purpose of the present article to put forward a different approach to these phenomena. Namely, we show th…

关于正算元上的自由交换幺半群

On the free commutative monoid over a positive operad

在向量物种框架下，研究由正算元生成的自由交换扭代数结构，提出$μ$-兼容算元概念，引入全新的嵌套pre-Lie算元（NPL-operads）并给出其构造及代数定义。

Schröder树、对映体公式与非交换概率

Schröder trees, antipode formulas and non-commutative probability

本文提出双张量Hopf代数中对映体的Schröder树无消去公式，应用于非交换概率，恢复累积量-矩公式并给出自由Wick多项式新表达。

Generalized shuffles related to Nijenhuis and TD-algebras

Shuffle and quasi-shuffle products are well-known in the mathematics literature. They are intimately related to Loday's dendriform algebras, and were extensively used to give explicit constructions of free commutative Rota-Baxter algebras. In the literature there exist at least two other Rota-Baxter type algebras, namely, the Nijenhuis algebra and the so-called TD-algebra. The explicit construction of the free unital commutative Nijenhuis algebra uses a modified quasi-shuffle product, called the right-shift shuffle. We show that another modification of the quasi-shuffle product, the so-called …