Open AccessOn Jonsson varieties and quasivarieties
Author(s) -
A.R. Yeshkeyev,
AUTHOR_ID
Publication year - 2021
Publication title -
ķaraġandy universitetìnìn̦ habaršysy. matematika seriâsy
Language(s) - English
Resource type - Journals
eISSN - 2663-5011
pISSN - 2518-7929
DOI - 10.31489/2021m4/151-157
Subject(s) - mathematics , convexity , regular polygon , variety (cybernetics) , class (philosophy) , pure mathematics , algebraically closed field , type (biology) , algebra over a field , geometry , computer science , artificial intelligence , ecology , statistics , financial economics , economics , biology
In this paper, new objects of research are identified, both from the standpoint of model theory and from the standpoint of universal algebra. Particularly, the Jonsson spectra of the Jonsson varieties and the Jonsson quasivarieties are considered. Basic concepts of 3 types of convexity are given: locally convex theory, ϕ(x)-convex theory, J-ϕ(x)-convex theory. Also, the inner and outer worlds of the model of the class of theories are considered. The main result is connected with the question of W. Forrest, which is related to the existential closed ness of an algebraically closed variety. This article gives a sufficient condition for a positive answer to this question.