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On algebras of distributions of binary formulas for theories of unars
D. Yu. Emelyanov Novosibirsk State University, 1, Pirogova st., Novosibirsk, 630090
Abstract:
Algebras of distributions of binary isolating and semi-isolating formulas
are derived structures for a given theory. These algebras reflect
binary links between realizations of
$1$-types defined by
formulas of the initial theory. Thus these are two sorts of
interrelated classification problems: 1) to define, for a given
class of theories, what algebras correspond to theories in this
class and to classify these algebras; 2) to classify theories in
the class in the dependence of algebras of isolating and
semi-isolating algebras that defined by these theories. For the
finite algebras of binary isolating formulas that description
implies the description for the algebra of binary semi-isolating
formulas.
In the paper, we give the description for algebras of
distributions of binary isolating formulas for theories of unars
with unary predicates, which is based on multiplication tables for
these algebras. It is proved that any theory of unar with unary
predicates defines, on a set of realizations of
$1$-type, an
algebra of of distributions of binary isolating formulas, which is
obtained by an algebra isomorphic to exactly one of the following
algebras: 1) the additive group of integer numbers, 2) a cyclic
group, 3) a cyclic algebra with given number of connected
components, 4) an algebra of free unar with given number of
preimages for each element; 5) the additive monoid of natural
numbers; 6) an algebra of low cones. In particular, if the unary
function, in the unar, is a substitution, then the algebra of
distributions of binary isolating formulas is defined by an
algebra isomorphic to exactly one of the following algebras: the
additive additive group of integer numbers, a cyclic group, a
cyclic algebra with given number of connected components. The
structures of these algebras allow to classify initial theories of
substitutions. Finite algebras are exhausted by the following
list: cyclic groups, cyclic algebras with given number of
connected components, algebras of low cones.
Keywords:
algebra of distributions of binary formulas, unar, elementary theory, unary predicate.
UDC:
510.67:512.577
MSC: 03C07,
03C60,
03G15,
20N02,
08A60