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A lattice L is slim if it is finite and the set of its join-irreducible elements contains no three-element antichain. Slim, semimodular lattices were previously characterized by G. Cz\'edli and E.T. Schmidt as the duals of the lattices…

Rings and Algebras · Mathematics 2012-08-31 Gábor Czédli , Tamás Dékány , László Ozsvárt , Nóra Szakács , Balázs Udvari

We characterize commutative idempotent involutive residuated lattices as disjoint unions of Boolean algebras arranged over a distributive lattice. We use this description to introduce a new construction, called gluing, that allows us to…

Logic · Mathematics 2021-08-27 Peter Jipsen , Olim Tuyt , Diego Valota

We classify the homogeneous finite-dimensional permutation structures, i.e., homogeneous structures in a language of finitely many linear orders, giving a nearly complete answer to a question of Cameron, and confirming the classification…

Logic · Mathematics 2020-02-26 Samuel Braunfeld , Pierre Simon

A countable structure is said to be extendible if it has the same Scott sentence as some uncountable structure. Rigid structures are not extendible. We give an example of an extendible model with a rigid elementary extension.

Logic · Mathematics 2017-11-29 Paul B. Larson , Saharon Shelah

In this paper, we present a simple lattice-theoretic characterization for affine buildings of type A. We introduce a class of modular lattices, called uniform modular lattices, and show that uniform modular lattices and affine buildings of…

Combinatorics · Mathematics 2019-09-20 Hiroshi Hirai

We outline the theory of sets with distributive operations: multishelves and multispindles, with examples provided by semi-lattices, lattices and skew lattices. For every such a structure we define multi-term distributive homology and show…

Geometric Topology · Mathematics 2013-12-17 Jozef H. Przytycki , Krzysztof K. Putyra

Let $\mathcal W$ be a nontrivial variety of lattices, and let $L$ be a finite lattice in $\mathcal W$. The congruence density of $L$ with respect to $\mathcal W$ is the number of congruences of $L$ divided by the maximum number of…

Rings and Algebras · Mathematics 2026-03-13 Gábor Czédli

We investigate the complexity of the lattice of local clones over a countably infinite base set. In particular, we prove that this lattice contains all algebraic lattices with at most countably many compact elements as complete sublattices,…

Rings and Algebras · Mathematics 2008-01-17 Michael Pinsker

We present distributions of countable models and correspondent structural characteristics of complete theories with continuum many types: for prime models over finite sets relative to Rudin-Keisler preorders, for limit models over types and…

Logic · Mathematics 2012-10-16 Roman A. Popkov , Sergey V. Sudoplatov

We show that all sufficiently nice $\lambda$-sets are countable dense homogeneous ($\mathsf{CDH}$). From this fact we conclude that for every uncountable cardinal $\kappa \le \mathfrak{b}$ there is a countable dense homogeneous metric space…

General Topology · Mathematics 2018-09-19 Rodrigo Hernández-Gutiérrez , Michael Hrušák , Jan van Mill

We obtain several results concerning the concept of isotypic structures. Namely we prove that any field of finite transcendence degree over a prime subfield is defined by types; then we construct isotypic but not isomorphic structures with…

Logic · Mathematics 2025-06-18 Pavel Gvozdevsky

It is well known that knots are countable in ordinary knot theory. Recently, knots {\it with intersections} have raised a certain interest, and have been found to have physical applications. We point out that such knots --equivalence…

General Relativity and Quantum Cosmology · Physics 2009-10-28 Norbert Grot , Carlo Rovelli

In [BGLM] and [GLNP] it was conjectured that if $H$ is a simple Lie group of real rank at least 2, then the number of conjugacy classes of (arithmetic) lattices in $H$ of covolume at most $x$ is $x^{(\gamma(H)+o(1))\log x/\log\log x}$ where…

Group Theory · Mathematics 2018-04-03 Mikhail Belolipetsky , Alex Lubotzky

In this paper, we introduce a class of hypercompositional structures called dualizable L-mosaics. We prove that their category is equivalent to that formed by ortholattices and we formulate an algebraic property characterizing…

Category Theory · Mathematics 2025-12-17 Nicolò Cangiotti , Alessandro Linzi , Enrico Talotti

We show that Morley's theorem on the number of countable models of a countable first-order theory becomes an undecidable statement when extended to second-order logic. More generally, we calculate the number of equivalence classes of…

Logic · Mathematics 2023-07-06 Christopher J. Eagle , Clovis Hamel , Sandra Müller , Franklin D. Tall

In this article we introduce the study of the number of pairs of non-comparable elements in a distributive lattice $\L$. We give several tight lower and upper bounds for the number and give as an application the lattices precisely for which…

Combinatorics · Mathematics 2014-05-06 Himadri Mukherjee

We prove that every orientable infinite type surface without boundary and finite genus has a Riemann surface structure such that its modular group of quasiconformal homeomorphisms is countable.

Geometric Topology · Mathematics 2024-08-26 Rogelio Niño Hernández

This work proves that the process of gluing finite lattices to form a larger lattice is bijective, that is each lattice is the glued sum of a unique system of finite lattices, provided the class of lattices is constrained to modular,…

Combinatorics · Mathematics 2025-03-19 Dale R. Worley

In this article we construct uncountably many new homogeneous locally finite Steiner triple systems of countably infinite order as Fra\"{\i}ss\'{e} limits of classes of finite Steiner triple systems avoiding certain subsystems. The…

Combinatorics · Mathematics 2021-03-10 Daniel Horsley , Bridget S. Webb

Unitally nondistributive quantales are unital quantales such that the unit is approximable by the totally below relation and does not meet-distribute over arbitrary joins. It is shown that the underlying nondistributive complete lattice…

General Topology · Mathematics 2024-12-02 Javier Gutiérrez García , Ulrich Höhle