Description
Pioneer in mathematical logic and theoretical computer science, Kalmár defined what are known as elementary functions, number-theoretic functions (i.e. those based on the natural numbers) built up from the notions of composition and variables, the constants 0 and 1, repeated addition + of the constants, proper subtraction ∸, bounded summation and bounded product (Kleene 1952:526).
Elimination of the bounded product from this list yields the subelementary or lower elementary functions. By use of the abstract computational model called a register machine, Schwichtenberg provided a demonstration that "all elementary functions are computable and totally defined" (Schwichtenberg 58).
