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We introduce the notion of an arithmetical type of combinatorial family of reals, which serves to generalize different types of families such as mad families, maximal cofinitary groups, ultrafilter bases, splitting families and other…

Logic · Mathematics 2023-12-18 Vera Fischer , Lukas Schembecker

We study two different types of (maximal) almost disjoint families: very mad families and (maximal) cofinitary groups. For the very mad families we prove the basic existence results. We prove that MA implies there exist many pairwise…

Logic · Mathematics 2009-10-05 Bart Kastermans

Using countable support iteration of $S$-proper posets, for some appropriate stationary set $S$, we obtain a generic extension of the constructible universe, in which $\mathfrak{b}=\mathfrak{c}=\aleph_2$ and there is a maximal cofinitary…

Logic · Mathematics 2016-03-10 Vera Fischer , Sy David Friedman , Asger Törnquist

We construct a Borel maximal eventually different family.

Logic · Mathematics 2016-05-24 Haim Horowitz , Saharon Shelah

We show that there is an effectively closed maximal eventually different family of functions in spaces of the form $\prod_n F(n)$ for $F\colon \mathbb{N} \to \mathbb{N}\cup\{\mathbb{N}\}$ and give an exact criterion for when there exists an…

Logic · Mathematics 2022-10-11 David Schrittesser

Let $\RR_S$ denote the expansion of the real ordered field by a family of real-valued functions $S$, where each function in $S$ is defined on a compact box and is a member of some quasianalytic class which is closed under the operations of…

Logic · Mathematics 2010-08-17 Daniel J. Miller

We study ultrafilters on countable sets and reaping families which are indestructible by Sacks forcing. We deal with the combinatorial characterization of such families and we prove that every reaping family of size smaller than the…

Logic · Mathematics 2021-10-18 David Chodounský , Osvaldo Guzmán , Michael Hrušák

We give a combinatorial characterization of when a maximal almost disjoint family of a weakly compact cardinal $\kappa$ is indestructible by the higher random forcing $\mathbb Q_\kappa$. We then use this characterisation to show that…

Logic · Mathematics 2019-04-10 Thomas Baumhauer

Given an initial family of sets, we may take unions, intersections and complements of the sets contained in this family in order to form a new collection of sets; our construction process is done recursively until we obtain the last family.…

Combinatorics · Mathematics 2024-09-11 Jorge Garcia , Rosemarie Bongers , Jonathan Detgen , Walter Morales

We prove that the spectrum of Van Douwen families is closed under singular limits. For any maximal eventually different family Raghavan defined in an associated ideal which measures how far the family is from being Van Douwen. Under CH we…

Logic · Mathematics 2026-02-25 Lukas Schembecker

For Van Douwen families, maximal families of eventually different permutations and maximal ideal independent families we show that the existence of a $\Sigma^1_2$ family implies the existence of a $\Pi^1_1$ family of the same size. We also…

Logic · Mathematics 2026-02-27 Julia Millhouse , Lukas Schembecker

Assuming that every set is constructible, we find a $\Pi^1_1$ maximal cofinitary group of permutations of $\mathbb N$ which is indestructible by Cohen forcing. Thus we show that the existence of such groups is consistent with arbitrarily…

Logic · Mathematics 2022-11-09 Vera Fischer , David Schrittesser , Asger Törnquist

The notion of constructible functions in the setting of tame real geometry has been introduced by Cluckers and Dan Miller in their work on parametric integration of globally subanalytic functions. A function on a globally subanalytic set is…

Logic · Mathematics 2026-04-28 Tobias Kaiser

Let $A\subset \mathbb{N}^{n}$ be an $r$-wise $s$-union family, that is, a family of sequences with $n$ components of non-negative integers such that for any $r$ sequences in $A$ the total sum of the maximum of each component in those…

Combinatorics · Mathematics 2016-06-03 Peter Frankl , Masashi Shinohara , Norihide Tokushige

Near-vector spaces extend linear algebra tools to non-linear algebraic structures, enabling the study of non-linear problems. However, explicit constructions remain rare. This paper introduces a broad computable family of near-vector…

Rings and Algebras · Mathematics 2025-04-07 L. Boonzaaier , S. Marques , D. Moore

We study the join-semilattice of constructibility real degrees in the side-by-side Sacks model, the model of set theory obtained by forcing with a countable-support product of infinitely many Sacks forcings over the constructible universe.…

Logic · Mathematics 2026-02-09 Lorenzo Notaro

Factoring out the spin $1$ subalgebra of a $ W $ algebra leads to a new $ W $ structure which can be seen either as a rational finitely generated $ W $ algebra or as a polynomial non-linear $ W_\infty$ realization.

High Energy Physics - Theory · Physics 2009-10-22 F. Delduc , L. Frappat , P. Sorba , F. Toppan , E. Ragoucy

We prove that the generic maximal independent family obtained by iteratively forcing with the Mathias forcing relative to diagonalization filters is densely maximal. Moreover, by choosing the filters with some care one can ensure the family…

Logic · Mathematics 2023-06-19 Vera Fischer , Corey Bacal Switzer

We call an $\alpha \in \mathbb{R}$ regainingly approximable if there exists a computable nondecreasing sequence $(a_n)_n$ of rational numbers converging to $\alpha$ with $\alpha - a_n < 2^{-n}$ for infinitely many $n \in \mathbb{N}$. We…

Logic · Mathematics 2026-02-11 Peter Hertling , Rupert Hölzl , Philip Janicki

It is shown the construction of a module structure [2] with universe over a set of a particular kind of mathematical proofs, the base ring of this module will be built on a maximal consistent extension of a set of propositions, this…

Logic · Mathematics 2013-07-25 Kevin Davila Castellar , Ismael Gutierrez Garcia
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