John T. Griesmer

activity

20242026

collaborators

5 papers

math.DS2026

Bohr sets in sumsets III: expanding difference sets and almost Bohr sets

Pierre-Yves Bienvenu, John T. Griesmer, Anh N. Le +1

Let $G$ be a discrete abelian group. FÃ¸lner showed that if $A \subseteq G$ has positive upper Banach density, then $A - A$ contains an almost Bohr set -- a set of the form $B \set…

math.CO2026

Kneser- and Jin-type inverse theorems in discrete abelian groups

John T. Griesmer

We characterize the pairs of sets $A, B$ in an arbitrary (countable or uncountable) discrete abelian group $I^$ satisfying $m ~ (A + B) < m ~ (A) + m ~ (B)$ , where $\tilde…

math.NT2025

Discrete sumsets with one large summand

John T. Griesmer

If $A$ and $B$ are subsets of an abelian group, their sumset is $A + B := {a + b : a \in A, b \in B}$ . We study sumsets in discrete abelian groups, where at least one summand has positive…

math.DS2024

Separating topological recurrence from measurable recurrence: exposition and extension of Kriz's example

John T. Griesmer

We prove that for every infinite set $E \subset Z$ , there is a set $S \subset E - E$ which is a set of topological recurrence and not a set of measurable recurrence. This exten…

math.DS2024

Separating measurable recurrence from strong recurrence via rigidity sequences

John T. Griesmer

If $G$ is an abelian group, we say $S \subset G$ is a set of recurrence if for every probability measure preserving $G$ -system $(X, I^¼, T)$ and every $D \subset X$ having $I^¼ (D) > 0$ , th…