3 papers
math.CO2026
The -Divisor Graph on is Planar and 3-Colorable
Michael D. Walton, Zachary D. Walton
We prove that a divisor graph on an interval of integers is a planar graph whenever the interval satisfies , and that 7 is the greatest such real number for which…
math.LO2026
Examples of non-tame abstract elementary classes of abelian groups
Daniel Herden, Marcos Mazari-Armida, Michael D. Walton
We construct an abstract elementary class of torsion-free abelian groups such that is not -tame but is -tame. This answers a question of [BoVa17]…
math.LO2026
An unstable abstract elementary class of modules: A variation of Paolini-Shelah's example
Daniel Herden, Marcos Mazari-Armida, Michael D. Walton
We construct a class of torsion-free abelian groups such that is an abstract elementary class with $\operatorname{LS}(\hat{\mathbf{K}…