D. Herden

collaborators

3 papers

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 $K_{1}$ of torsion-free abelian groups such that $K_{1}$ is not $(< ℵ_{0})$ -tame but is $ℵ_{0}$ -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 $K^$ of torsion-free abelian groups such that $K^= (K^, \leq_{p})$ is an abstract elementary class with $\operatorname{LS}(\hat{\mathbf{K}…

math.CO2026

The partial derivative of ratios of Schur polynomials and applications to symplectic quotients

Hans-Christian Herbig, Daniel Herden, Harper Kolehmainen +1

We show that a ratio of Schur polynomials $s_{I^} »/ s_{I ¨} $ associated to partitions $I^»$ and $I ¨ $ such that $I^» ⊊ I ¨ $ has a negative partial derivative at any point where all var…