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:
Ordered exponential
where the term "n" = 0 is equal to 1 and
where formula_3 is a higher-order operation that ensures the exponential is time-ordered: any product of "a"("t") that occurs in the expansion of the exponential must be ordered such that the value of "t" is increasing from right to left of the product; a schematic example:
This restriction is necessary as products in the algebra are not necessarily commutative.