On finite approximability of superintuitionistic logics

Finite approximability is proved for superintuitionistic propositional logics generated by formulas satisfying a certain sufficient condition. As a corollary, one obtains the finite approximability of logics generated by formulas with one variable. A formula with two variables is constructed which generates a logic not finitely approximable. All previously known finitely approximable logics have been generated by formulas in three or more variables (see RZhMat., 1971, 5A64 and 1972, 6A84).
Figures: 1.
Bibliography: 6 titles.