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We prove that certain closable derivations on the GNS Hilbert space associated with a non-tracial weight on a von Neumann algebra give rise to GNS-symmetric semigroups of contractive completely positive maps on the von Neumann algebra.

Operator Algebras · Mathematics 2023-07-11 Melchior Wirth

We construct a measure on omega-one^2 over the ground model in the forcing extension of a measure algebra, and investigate when measure theoretic properties of some measurable colouring of omega-one^2 imply the existence of an uncountable…

Logic · Mathematics 2007-05-23 James Hirschorn

We initiate the study of the spectrum $Vspec(\kappa)$ of sets that can be realized as the vanishing levels $V(T)$ of a normal $\kappa$-tree $T$. The latter is an invariant in the sense that if $T$ and $T'$ are club-isomorphic, then the…

Logic · Mathematics 2023-09-28 Assaf Rinot , Shira Yadai , Zhixing You

Let $\mathcal{T}_n$ be the set of trees with $n$ vertices. Suppose that each tree in $\mathcal{T}_n$ is equally likely. We show that the number of different rooted trees of a tree equals $(\mu_r+o(1))n$ for almost every tree of…

Combinatorics · Mathematics 2013-05-21 Xueliang Li , Yiyang Li , Yongtang Shi

For a noncommutative Orlicz space associated with a semifnite von Neumann algebra, a faithful normal semifnite trace and an Orlicz function satisfying $(\delta_2,\Delta_2)-$condition, an individual ergodic theorem is proved.

Operator Algebras · Mathematics 2016-02-02 Vladimir Chilin , Semyon Litvinov

In this paper, we derive a new monotonicity formula for the plurisuhbarmonic functions on complete K\"ahler manifolds with nonnegative bisectional curvature. As applications we derive the sharp estimates for the dimension of the spaces of…

Differential Geometry · Mathematics 2007-05-23 Lei Ni

We show that many countable support iterations of proper forcings preserve Souslin trees. We establish sufficient conditions in terms of games and we draw connections to other preservation properties. We present a proof of preservation…

Logic · Mathematics 2013-09-03 Heike Mildenberger , Saharon Shelah

We study rings of integral modular forms for congruence subgroups as modules over the ring of integral modular forms for the full modular group. In many cases these modules are free or decompose at least into well-understood pieces. We…

Algebraic Geometry · Mathematics 2023-03-01 Lennart Meier

Let $\overline{\mathfrak{S}}_\infty$ denote the set of all bijections of natural numbers. Consider the action of $\overline{\mathfrak{S}}_\infty$ on a measure space $\left( X,\mathfrak{M},\mu \right)$, where $\mu$ is…

Representation Theory · Mathematics 2019-02-26 Nikolay Nessonov

We introduce two operads which own the set of planar forests as a basis. With its usual product and two other products defined by different types of graftings, the algebra of planar rooted trees H becomes an algebra over these operads. The…

Rings and Algebras · Mathematics 2009-01-16 Loïc Foissy

For a $k$-tree $T$, we prove that the maximum local mean order is attained in a $k$-clique of degree $1$ and that it is not more than twice the global mean order. We also bound the global mean order if $T$ has no $k$-cliques of degree $2$…

Combinatorics · Mathematics 2024-04-09 Stijn Cambie , Bradley McCoy , Stephan Wagner , Corrine Yap

This paper investigates some properties of the number of subtrees of a tree with given degree sequence. These results are used to characterize trees with the given degree sequence that have the largest number of subtrees, which generalizes…

Combinatorics · Mathematics 2012-09-04 Xiu-Mei Zhang , Xiao-Dong Zhang , Daniel Gray , Hua Wang

We prove that the cone over a Dirichlet arrangement is supersolvable if and only if its Orlik-Solomon algebra is Koszul. This was previously shown for four other classes of arrangements. We exhibit an infinite family of cones over Dirichlet…

Combinatorics · Mathematics 2020-09-22 Bob Lutz

We enumerate total cyclic orders on $\left\{1,\ldots,n\right\}$ where we prescribe the relative cyclic order of consecutive triples $(i,{i+1},{i+2})$, these integers being taken modulo $n$. In some cases, the problem reduces to the…

Combinatorics · Mathematics 2020-07-10 Sanjay Ramassamy

Let $\mathfrak{S}_w(x)$ be the Schubert polynomial for a permutation $w$ of $\{1,2,\ldots,n\}$. For any given composition $\mu$, we say that $x^\mu \mathfrak{S}_w(x^{-1})$ is the complement of $\mathfrak{S}_w(x)$ with respect to $\mu$. When…

Combinatorics · Mathematics 2024-03-19 Neil J. Y. Fan , Peter L. Guo , Nicolas Y. Liu

We display the entire structure ${\cal R}_2$ coding $\Sigma_1$- and $\Sigma_2$-elementarity on the ordinals. This will enable the analysis of pure $\Sigma_3$-elementary substructures.

Logic · Mathematics 2021-06-10 Gunnar Wilken

We prove under $V=L$ that the inclusion modulo the non-stationary ideal is a $\Sigma_1^1$-complete quasi-order in the generalized Borel-reducibility hierarchy ($\kappa>\omega$). This improvement to known results in $L$ has many new…

Logic · Mathematics 2019-12-10 Tapani Hyttinen , Vadim Kulikov , Miguel Moreno

Assume GCH and let $\lambda$ denote an uncountable cardinal. We prove that if $\square_\lambda$ holds, then this may be witnessed by a coherent sequence $< C_\alpha | \alpha < \lambda^+ >$ with the following remarkable guessing property:…

Logic · Mathematics 2011-05-17 Assaf Rinot

Two-dimensional version of the classical Mycielski theorem says that for every comeager or conull set $X\subseteq [0,1]^2$ there exists a perfect set $P\subseteq [0,1]$ such that $P\times P\subseteq X\cup \Delta$. We consider…

General Topology · Mathematics 2019-05-23 Marcin Michalski , Robert Rałowski , Szymon Żeberski

Let $\Gamma$ be a finitely generated group, and let $\mu$ be a nondegenerate, finitely supported probability measure on $\Gamma$. We show that every co-compact $\Gamma$ action on a locally compact Hausdorff space admits a nonzero…

Group Theory · Mathematics 2025-09-16 Mohammedsaid Alhalimi , Tom Hutchcroft , Minghao Pan , Omer Tamuz , Tianyi Zheng