All Questions
5 questions with no upvoted or accepted answers
19
votes
0
answers
563
views
What algebraic properties are preserved by $\mathbb{N}\leadsto\beta\mathbb{N}$?
Given a binary operation $\star$ on $\mathbb{N}$, we can naturally extend $\star$ to a semicontinuous operation $\widehat{\star}$ on the set $\beta\mathbb{N}$ of ultrafilters on $\mathbb{N}$ as ...
- 20.5k
8
votes
0
answers
682
views
Is there any theorem achieving Conway's "Mathematician's Liberation Movement"
John Conway on in the appendix to part zero of ONAG describes a "Mathematician's Liberation Movement". The goal would be to give mathematicians the freedom to create mathematical theories with the ...
- 6,353
4
votes
0
answers
247
views
Cantor-Bernstein phenomena for structures (and a "moderate zigzag" property)
My favorite proof of the Cantor-Bernstein theorem is the one that argues by "histories" - given injections $f:A\rightarrow B$ and $g:B\rightarrow A$, we identify each element of $A$ as ...
- 20.5k
3
votes
0
answers
99
views
Counting Eilenberg/Schutzenberger-type definitions of pseudovarieties
See Eilenberg/Schutzenberger, On pseudovarieties for background on pseudovarieties. I've phrased things in terms of pairs-of-sets to avoid some annoying language about multisets. Also, I'm aware that ...
- 20.5k
3
votes
0
answers
117
views
Examples of algebras of inner elementary embeddings in model theory (as opposed to set theory)
The algebras of elementary embeddings have been studied from a set theoretic perspective and an algebraic perspective. I wonder is there is a purely model theoretic approach to the self-distributive ...
