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We introduce a new definition of topological degree for a meaningful class of operators which need not be continuous. Subsequently, we derive a number of fixed point theorems for such operators. As an application, we deduce a new existence…

Classical Analysis and ODEs · Mathematics 2017-01-10 Rubén Figueroa , Rodrigo López Pouso , Jorge Rodríguez López

We prove that continuous reducibility is a well-quasi-order on the class of continuous functions between separable metrizable spaces with analytic zero-dimensional domain. To achieve this, we define scattered functions, which generalize…

Logic · Mathematics 2024-10-18 Raphaël Carroy , Yann Pequignot

Given a subshift over an arbitrary alphabet, we construct a representation of the associated unital algebra. We describe a criteria for the faithfulness of this representation in terms of the existence of cycles with no exits. Subsequently,…

Rings and Algebras · Mathematics 2023-06-29 Daniel Gonçalves , Danilo Royer

Submodular set functions are undoubtedly among the most important building blocks of combinatorial optimization. Somewhat surprisingly, continuous counterparts of such functions have also appeared in an analytic line of research where they…

Combinatorics · Mathematics 2024-06-10 Kristóf Bérczi , Boglárka Gehér , András Imolay , László Lovász , Tamás Schwarcz

We give simple characterizations of the category PAsm(A) of partitioned assemblies, and of the realizability topos RT(A) over a partial combinatory algebra A. This answers the question for an 'extensional characterization' of realizability…

Category Theory · Mathematics 2018-08-06 Jonas Frey

Using the closure operator that defines a subtractive ideal of a semiring $S$, in this note we introduce a topology on the set of all ideals of $S$ induced by that operator. We show that the corresponding subtractive space is $T_0$ and…

Rings and Algebras · Mathematics 2023-03-28 Amartya Goswami

We study the non-uniqueness of factorizations of non zero-divisors into atoms (irreducibles) in noncommutative rings. To do so, we extend concepts from the commutative theory of non-unique factorizations to a noncommutative setting. Several…

Rings and Algebras · Mathematics 2015-09-03 Nicholas R. Baeth , Daniel Smertnig

The Arthur-Nimue-Merlin degrees are a generalization of the Turing degrees introduced by Kihara as a tangible description of the partially ordered set of Lawvere-Tierney topologies on the effective topos (equivalently, subtoposes of the…

Logic · Mathematics 2026-03-23 Jean Abou Samra , David Alexander Madore

The basic notions of quantum mechanics are formulated in terms of separable infinite dimensional Hilbert space $\mathcal{H}$. In terms of the Hilbert lattice $\mathcal{L}$ of closed linear subspaces of $\mathcal{H}$ the notions of state and…

Logic in Computer Science · Computer Science 2023-06-22 Eike Neumann , Martin Pape , Thomas Streicher

In this paper the concept of $\mathbb{F}$-functorial of a finite group was introduced. These functorials have many properties of the Fitting subgroup of a soluble group and the generalized Fitting subgroup of a finite group. It was shown…

Group Theory · Mathematics 2021-03-25 Viachaslau I. Murashka , Alexander F. Vasil'ev

We study multidimensional minimal and quasiperiodic shifts of finite type. We prove for these classes several results that were previously known for the shifts of finite type in general, without restriction. We show that some quasiperiodic…

Discrete Mathematics · Computer Science 2021-07-01 Bruno Durand , Andrei Romashchenko

Irreducible representations (irreps) of $\mathbb{Z}_2^2$-graded supersymmetry algebra of ${\cal N}=2$ are obtained by the method of induced representation and they are used to derive $\mathbb{Z}_2^2$-graded supersymmetric classical actions.…

Mathematical Physics · Physics 2022-09-13 N. Aizawa , S. Doi

In this paper we study the embedded topology of reducible plane curves having a smooth irreducible component. In previous studies, the relation between the topology and certain torsion classes in the Picard group of degree zero of the…

Algebraic Geometry · Mathematics 2022-06-01 E. Artal Bartolo , S. Bannai , T. Shirane , H. Tokunaga

Selman's Theorem in classical Computability Theory gives a characterization of the enumeration reducibility for arbitrary sets in terms of the enumeration reducibility on the total sets: $A \le_e B \iff \forall X [X \equiv_{e} X \oplus…

Logic · Mathematics 2019-02-13 Dávid Natingga

We introduce the notion of directed diagrammatic reducibility which is a relative version of diagrammatic reducibility. Directed diagrammatic reducibility has strong group theoretic and topological consequences. A multi-relator version of…

Geometric Topology · Mathematics 2021-01-19 Jens Harlander , Stephan Rosebrock

Given a countable structure $\mathcal{A}$, the degree spectrum of $\mathcal{A}$ is the set of all Turing degrees which can compute an isomorphic copy of $\mathcal{A}$. One of the major programs in computable structure theory is to determine…

Logic · Mathematics 2025-11-07 Matthew Harrison-Trainor

We present a local and constructive differential geometric description of finite-dimensional solvable and transitive Lie algebras of vector fields. We show that it implies a Lie's conjecture for such Lie algebras. Also infinite-dimensional…

Differential Geometry · Mathematics 2020-07-13 Katarzyna Grabowska , Janusz Grabowski

In the current paper we attempt to transfer the notion of the projectional entropy, originally defined for multidimensional subshifts, to the case of actions of amenable groups. The main theorem states that if a system is strongly…

Dynamical Systems · Mathematics 2024-03-05 Michał Prusik

Represented spaces form the general setting for the study of computability derived from Turing machines. As such, they are the basic entities for endeavors such as computable analysis or computable measure theory. The theory of represented…

Logic · Mathematics 2015-03-04 Arno Pauly

We construct a class of lattices in three and higher dimensions for which the number of dimer coverings can be determined exactly using elementary arguments. These lattices are a generalization of the two-dimensional kagome lattice, and the…

Statistical Mechanics · Physics 2009-11-13 Deepak Dhar , Samarth Chandra