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We show that the universal homogeneous partial order has finite big Ramsey degrees and discuss several corollaries. Our proof relies on parameter spaces and the Carlson-Simpson theorem rather than on (a strengthening of) the…

Combinatorics · Mathematics 2025-06-09 Jan Hubička

We define and study expansion problems on countable structures in the setting of descriptive combinatorics. We consider both expansions on countable Borel equivalence relations and on countable groups, in the Borel, measure and category…

Logic · Mathematics 2025-05-13 Michael Wolman

We investigate various homotopy invariant formulations of commutative algebra in the context of rational homotopy theory. The main subject is the complete intersection condition, where we show that a growth condition implies a structure…

Algebraic Topology · Mathematics 2010-06-11 J. P. C. Greenlees , K. Hess , S. Shamir

We prove that the cyclic homology of a saturated $A_\infty$ category admits the structure of a `polarized variation of Hodge structures', building heavily on the work of many authors: the main point of the paper is to present complete…

K-Theory and Homology · Mathematics 2019-12-11 Nick Sheridan

We prove a general structure theorem for finitely presented torsion modules over a class of commutative rings that need not be Noetherian. As a first application, we then use this result to study the Weil- \'etale cohomology groups of…

Number Theory · Mathematics 2024-01-08 David Burns , Alexandre Daoud , Dingli Liang

We prove two theorems on cohomologically complete complexes. These theorems are inspired by, and yield an alternative proof of, a recent theorem of P. Schenzel on complete modules.

Commutative Algebra · Mathematics 2014-04-30 Amnon Yekutieli

Canonical extension of finitary ordered structures such as lattices, posets, proximity lattices, etc., is a certain completion which entirely describes the topological dual of the ordered structure and it does so in a purely algebraic and…

Category Theory · Mathematics 2022-05-12 Tomáš Jakl

Suppose given a commutative quadrangle in a Verdier triangulated category such that there exists an induced isomorphism on the horizontally taken cones. Suppose that the endomorphism ring of the initial or the terminal corner object of this…

K-Theory and Homology · Mathematics 2007-09-03 Alberto Canonaco , Matthias Kuenzer

We characterize the corings whose category of comodules has a generating set of small projective comodules in terms of the (non commutative) descent theory. In order to extricate the structure of these corings, we give a generalization of…

Rings and Algebras · Mathematics 2007-05-23 L. El Kaoutit , J. Gomez-Torrecillas

Answering some of the main questions from [MR13], we show that whenever $\kappa$ is a cardinal satisfying $\kappa^{< \kappa} = \kappa > \omega$, then the embeddability relation between $\kappa$-sized structures is strongly invariantly…

Logic · Mathematics 2021-02-18 Filippo Calderoni , Heike Mildenberger , Luca Motto Ros

We prove that each \omega-categorical, generically stable group is solvable-by-finite.

Logic · Mathematics 2023-11-14 Jan Dobrowolski , Krzysztof Krupinski

An almost para-CR structure on a manifold $M$ is given by a distribution $HM \subset TM$ together with a field $K \in \Gamma({\rm End}(HM))$ of involutive endomorphisms of $HM$. If $K$ satisfies an integrability condition, then $(HM,K)$ is…

Differential Geometry · Mathematics 2008-08-05 Dmitri V. Alekseevsky , Costantino Medori , Adriano Tomassini

We classify primitive, rank 1, omega-categorical structures having polynomially many types over finite sets. For a fixed number of 4-types, we show that there are only finitely many such structures and that all are built out of finitely…

Logic · Mathematics 2022-08-02 Pierre Simon

We prove that every \omega-categorical, generically stable group is nilpotent-by-finite and that every \omega-categorical, generically stable ring is nilpotent-by-finite.

Logic · Mathematics 2023-11-14 Jan Dobrowolski , Krzysztof Krupinski

In [CPPP] it was shown that Engel structures satisfy an existence $h$-principle, and the question of whether a full $h$-principle holds was left open. In this note we address the classification problem, up to Engel deformation, of Cartan…

Symplectic Geometry · Mathematics 2017-08-02 Álvaro del Pino

Homotopy connectedness theorems for complex submanifolds of homogeneous spaces (sometimes referred to as theorems of Barth-Lefshetz type) have been established by a number of authors. Morse Theory on the space of paths lead to an elegant…

Differential Geometry · Mathematics 2014-09-12 Chaitanya Senapathi

In \cite{To} S. Todorcevic introduced the notion of a topological Ramsey space and a list of axioms required to be satisfied by any such a space. Here we show that any topological Ramsey space that satisfies a strengthened version of one of…

Logic · Mathematics 2017-03-20 Dimitris Vlitas

We show that semi-infinite cohomology of a finite dimensional graded algebra (satisfying some additional requirements) are a particular case of a general categorical construction. The motivating example is provided by small quantum groups…

Representation Theory · Mathematics 2007-05-23 Roman Bezrukavnikov

Ramsey algebras is an attempt to investigate Ramsey spaces generated by algebras in a purely combinatorial fashion. Previous studies have focused on the basic properties of Ramsey algebras and the study of a few specific examples. In this…

Logic · Mathematics 2020-04-23 Zu Yao Teoh

We prove that for any choice of parameters $k,t,\lambda$ the class of all finite ordered designs with parameters $k,t,\lambda$ is a Ramsey class.

Combinatorics · Mathematics 2017-05-09 Jan Hubička , Jaroslav Nešetřil