This article is cited in
1 paper
Properties of $s\Sigma$-reducibility
A. I. Stukachevab a Novosibirsk State University, ul. Pirogova 2, Novosibirsk, 630090, Russia
b Sobolev Institute of Mathematics, pr. Akad. Koptyuga 4, Novosibirsk, 630090, Russia
Abstract:
We couch the definition of
$s\Sigma$-reducibility on structures, describe some properties of
$s\Sigma$-reducibility, and also exemplify explicitly how to use it. In particular, we consider natural expansions of structures such as Morleyization and Skolemization. Previously, a class of quasiregular structures was defined to be a class of fixed points of Morleyization with respect to
$s\Sigma$-reducibility, extending the class of models of regular theories and the class of effectively model-complete structures. It was proved that an
$\mathrm{HF}$-superstructure over a quasiregular structure is quasiresolvent and, consequently, has a universal
$\Sigma$-function and possesses the reduction property. Here we show that an
$\mathrm{HF}$-superstructure over a quasiregular structure has the
$\Sigma$-uniformization property iff with respect to
$s\Sigma$-reducibility this structure is a fixed point for some of its Skolemizations with an extra property, that of well-definededness. In this case an
$\mathrm{HF}$-superstructure and a Moschovakis superstructure over a given structure are
$s\Sigma$-equivalent.
Keywords:
generalized computability, model theory, model completeness, decidability, uniformization property.
UDC:
510.5 Received: 06.06.2013
Revised: 29.08.2014