Abstract

this article a language L for the predicate calculus whose only predicate symbol = is the 2-ary one for the equality and whose function symbols are a 2-ary one ap for application together with a set of 0-ary symbols divided into ground symbols and unknowns. The unknowns correspond to the function letters of [2], page 263, while the ground symbols to its function symbols. We remark: unknowns are function symbols of the language L that should not be confused with variables of L. Usually, we use capital letters X , Y , Z, perhaps indexed, for denoting unknowns; the letters u, v, w for variables; other small letters and numbers for ground symbols.

Citations