A counterexample to the reconstruction of ω-categorical structures from their endomorphism monoid

Research output: Contribution to journalResearch articleContributedpeer-review

Contributors

  • Manuel Bodirsky - , Institute of Algebra, TUD Dresden University of Technology (Author)
  • David Evans - , Imperial College London (Author)
  • Michael Kompatscher - , Vienna University of Technology (Author)
  • Michael Pinsker - , Vienna University of Technology, Charles University Prague (Author)

Abstract

We present an example of two countable ω-categorical structures, one of which has a finite relational language, whose endomorphism monoids are isomorphic as abstract monoids, but not as topological monoids—in other words, no isomorphism between these monoids is a homeomorphism. For the same two structures, the automorphism groups and polymorphism clones are isomorphic, but not topologically isomorphic. In particular, there exists a countable ω-categorical structure in a finite relational language which can neither be reconstructed up to first-order biinterpretations from its automorphism group, nor up to existential positive bi-interpretations from its endomorphism monoid, nor up to primitive positive bi-interpretations from its polymorphism clone.

Details

Original languageEnglish
Pages (from-to)57-82
Number of pages26
JournalIsrael journal of mathematics
Volume224
Issue number1
Publication statusPublished - 1 Apr 2018
Peer-reviewedYes

External IDs

ORCID /0000-0001-8228-3611/work/142241084

Keywords

ASJC Scopus subject areas