English

An example of a Fra\"iss\'e class without a Kat\v{e}tov functor

Logic 2016-04-04 v1 Category Theory

Abstract

We disprove a conjecture from [W. Kubi\'s, D. Ma\v{s}ulovi\'c, Kat\v{e}tov functors, preprint, http://arxiv.org/abs/1412.1850] by showing the existence of a Fra\"iss\'e class C\mathcal{C} which does not admit a Kat\v{e}tov functor. On the other hand, we show that the automorphism group of the Fra\"iss\'e limit of C\mathcal{C} is universal, as it happens in the presence of a Kat\v{e}tov functor.

Cite

@article{arxiv.1604.00358,
  title  = {An example of a Fra\"iss\'e class without a Kat\v{e}tov functor},
  author = {Jan Grebík},
  journal= {arXiv preprint arXiv:1604.00358},
  year   = {2016}
}

Comments

6 pages

R2 v1 2026-06-22T13:23:31.196Z