Skip to main content
Diego Martinez's user avatar
Diego Martinez's user avatar
Diego Martinez's user avatar
Diego Martinez
  • Member for 5 years, 1 month
  • Last seen this week
comment
Følner sequences with weird shapes
These are great, thanks! These are precisely what I was asking for. However, what do you mean from "different angles"? Each pair is identical, right? Mind you, I think it's more or less clear without the need from another angle, but I spent several minutes looking for the 7 differences.
comment
Følner sequences with weird shapes
@VilleSalo I've heard more than once that Følner sets are usually strange, but this is of course personal. I do agree with you on the lamplighter, and it fits the question perfectly.
comment
Følner sequences with weird shapes
@YCor you are indeed right that "weird" is subjective. I just meant Folner sequences that are not balls. Hence your example of $\mathbb{Z}$ fits the question, but I'd like some other examples.
asked
Loading…
accepted
asked
Loading…
awarded
awarded
awarded
comment
Upper density of subsets of an amenable group
Just to add something to the already well written answer, there's an account of the relation between Szemeredi's theorem and Furstenberg-Zimmer's theorem in the excellent book of Kerr and Li about ergodic theory, where they not only treat $\mathbb{Z}$, but general discrete groups acting on locally compact Hausdorff spaces.
awarded
Loading…
Loading…
comment
Ascending sequences of idempotents in inverse semigroups
@Carl-Fredik, would you have the reference at hand? Or, maybe, just a sketch of the proof.
comment
Ascending sequences of idempotents in inverse semigroups
Thank you to both. @Ycor, what do you mean by "strongly distorted"? Would you have a reference where I could read about Bergman's Property?
awarded
Loading…