New operations in intuitionistic calculus

The question is studied of the possibility of extending the intuitionistic propositional calculus by adding single-valued one-place operations which are not expressible in terms of conjunction, disjunction, implication, or negation. There is constructed a system of correct calculi with new single-valued operations which is isomorphic to the family of proper extensions of the intuitionistic propositional calculus.Translated from Matematicheskie Zametki, Vol. 22, No. 1, pp. 23–28, July, 1977.The author wishes to thank L. L. Maksimova for his help with this paper.