Exponentiation
Exponentiation is a mathematical operation, written as , involving two numbers, the "base" and the "exponent" . When is a positive integer, exponentiation corresponds to repeated multiplication of the base: that is, is the product of multiplying bases:
ELEMENTARY
Whereas ELEMENTARY contains bounded applications of exponentiation (for example, formula_2), PR allows more general hyper operators (for example, tetration) which are not contained in ELEMENTARY.