English

Asymmetric regular types

Logic 2015-03-17 v1

Abstract

We study asymmetric regular types. If p\frak p is regular and AA-asymmetric then there exists a strict order such that Morley sequences in p\frak p over AA are strictly increasing (we allow Morley sequences to be indexed by elements of a linear order). We prove that for all MAM\supseteq A maximal Morley sequences in p\frak p over AA consisting of elements of MM have the same (linear) order type, denoted by \Invp,A(M)\Inv_{\frak p,A}(M), which does not depend on the particular choice of the order witnessing the asymmetric regularity. In the countable case we determine all possibilities for \Invp,A(M)\Inv_{\frak p,A}(M): either it can be any countable linear order, or in any MAM\supseteq A it is a dense linear order (provided that it has at least two elements). Then we study relationship between \Invp,A(M)\Inv_{\frak p,A}(M) and \Invq,A(M)\Inv_{\frak q,A}(M) when p\frak p and q\frak q are strongly regular, AA-asymmetric, and such that p\strokA\frak p_{\strok A} and q\strokA\frak q_{\strok A} are not weakly orthogonal. We distinguish two kinds on non-orthogonality: bounded and unbounded. In the bounded case we prove that \Invp,A(M)\Inv_{\frak p,A}(M) and \Invq,A(M)\Inv_{\frak q,A}(M) are either isomorphic or anti-isomorphic. In the unbounded case, \Invp,A(M)\Inv_{\frak p,A}(M) and \Invq,A(M)\Inv_{\frak q,A}(M) may have distinct cardinalities but we prove that their Dedekind completions are either isomorphic or anti-isomorphic. We provide examples of all four situations.

Keywords

Cite

@article{arxiv.1312.0222,
  title  = {Asymmetric regular types},
  author = {Slavko Moconja and Predrag Tanović},
  journal= {arXiv preprint arXiv:1312.0222},
  year   = {2015}
}
R2 v1 2026-06-22T02:18:21.967Z