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A closure system with the anti-exchange axiom is called a convex geometry. One geometry is called a sub-geometry of the other if its closed sets form a sublattice in the lattice of closed sets of the other. We prove that convex geometries…

Combinatorics · Mathematics 2014-01-29 Kira Adaricheva

A convex geometry is a closure system satisfying the anti-exchange property. This paper, following the work of K. Adaricheva and M. Bolat (2016) and the Polymath REU 2020 team, continues to investigate representations of convex geometries…

Combinatorics · Mathematics 2022-06-14 Kira Adaricheva , Evan Daisy , Ayush Garg , Zachary King , Grace Ma , Michelle Olson , Cat Raanes , James Thompson

Building sets were introduced in the study of wonderful compactifications of hyperplane arrangement complements and were later generalized to finite meet-semilattices. Convex geometries, the duals of antimatroids, offer a robust…

Combinatorics · Mathematics 2025-11-12 Spencer Backman , Richard Danner

A convex geometry is a closure system satisfying the anti-exchange property. In this work we document all convex geometries on 4- and 5-element base sets with respect to their representation by circles on the plane. All 34 non-isomorphic…

We propose an abstract definition of convex spaces as sets where one can take convex combinations in a consistent way. A priori, a convex space is an algebra over a finitary version of the Giry monad. We identify the corresponding Lawvere…

Metric Geometry · Mathematics 2015-10-20 Tobias Fritz

Various characterizations of finite convex geometries are well known. This note provides similar characterizations for possibly infinite convex geometries whose lattice of closed sets is strongly coatomic and lower continuous. Some classes…

Combinatorics · Mathematics 2017-01-27 Kira Adaricheva , J. B. Nation

Convex geometries are closure systems satisfying the anti-exchange axiom. Every finite convex geometry can be embedded into a convex geometry of finitely many points in an n-dimensional space equipped with a convex hull operator, by the…

Combinatorics · Mathematics 2016-09-02 Kira Adaricheva , Madina Bolat

The following article treats about convex geometries which are lower semi-modular and join semi-distributive lattices. Firstly, it is shown that there is a class $K$ of infinite convex geometries which can be build out of finite ones by…

Logic · Mathematics 2025-09-10 Adam Mata

Convex semilattices are algebras that are at the same time a convex algebra and a semilattice, together with a distributivity axiom. These algebras have attracted some attention in the last years as suitable algebras for probability and…

Logic in Computer Science · Computer Science 2025-07-16 Ana Sokolova , Harald Woracek

We develop the fundamentals of a new theory of convex geometry -- which we call "broken line convex geometry". This is a theory of convexity where the ambient space is the rational tropicalization of a cluster variety, as opposed to an…

Algebraic Geometry · Mathematics 2026-01-19 Juan Bosco Frías-Medina , Timothy Magee

Let F be a finite set of circles in the plane. We point out that the usual convex closure restricted to F yields a convex geometry, that is, a combinatorial structure introduced by P. H Edelman in 1980 under the name "anti-exchange closure…

Rings and Algebras · Mathematics 2013-05-22 Gábor Czédli

Convex geometry is a closure space $(G,\phi)$ with the anti-exchange property. A classical result of Edelman and Jamison (1985) claims that every finite convex geometry is a join of several linear sub-geometries, and the smallest number of…

Combinatorics · Mathematics 2018-08-09 Kira Adaricheva , Gent Gjonbalaj

A convex geometry is finite zero-closed closure system that satisfies the anti-exchange property. Complexity results are given for two open problems related to representations of convex geometries using implication bases. In particular, the…

Computational Complexity · Computer Science 2022-11-17 Todd Bichoupan

In the paper we consider convex cones in infinite-dimensional real vector spaces which are endowed with no topology. The main purpose is to study an internal geometric structure of convex cones and to obtain an analytical description of…

Optimization and Control · Mathematics 2024-11-26 Valentin V. Gorokhovik

A closure endomorphism of a Hilbert algebra A is a mapping that is simultaneously an endomorphism of and a closure operator on A. It is known that the set CE of all closure endomorphisms of A is a distributive lattice where the meet of two…

Rings and Algebras · Mathematics 2022-11-03 Jānis Cīrulis

Problems related to projections on closed convex cones are frequently encountered in optimization theory and related fields. To study these problems, various unifying ideas have been introduced, including asymmetric vector-valued norms and…

Optimization and Control · Mathematics 2022-04-11 Jani Jokela

A mixed lattice is a lattice-type structure consisting of a set with two partial orderings, and generalizing the notion of a lattice. Mixed lattice theory has previously been studied in various algebraic structures, such as groups and…

Combinatorics · Mathematics 2024-04-10 Jani Jokela

Let $X$ be an ordered vector space. The net $\{x_\alpha\}\subseteq X$ is semi unbounded order convergent to $x$ (in symbol $x_\alpha\xrightarrow{suo}x$), if there is a net $\{y_\beta\}$, possibly over a different index set, such that…

Functional Analysis · Mathematics 2022-01-03 Masoumeh Ebrahimzadeh , Kazem Haghnejad Azar

Let V be a finite set and M a collection of subsets of V. Then M is an alignment of V if and only if M is closed under taking intersections and contains both V and the empty set. If M is an alignment of V, then the elements of M are called…

Combinatorics · Mathematics 2011-07-07 J. Cáceres , O. R. Oellermann , M. L. Puertas

Graph convexity has been used as an important tool to better understand the structure of classes of graphs. Many studies are devoted to determine if a graph equipped with a convexity is a {\em convex geometry}. In this work we survey…

Discrete Mathematics · Computer Science 2024-09-05 Mitre C. Dourado , Marisa Gutierrez , Fábio Protti , Rudini Sampaio , Silvia Tondato
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