Аннотация:
We study approximations of theories both in general context and with respect to some natural classes of theories. Some kinds of approximations are considered, connections with finitely axiomatizable theories and minimal generating sets of theories as well as their $e$-spectra are found. $e$-categorical approximating families are introduced and characterized.
Ключевые слова:approximation of theory, combination of structures, closure, finitely axiomatizable theory, $e$-spectrum.