**Boolean functions**, sometimes also called switching functions, are functions that take as their input zero or more boolean values (1 or 0, true or false, etc.) and output a single boolean value. The number of inputs to the function is is called the arity of the function and is denoted as *k*. Every *k*-ary function can be written as a propositional formula, a sentence in propositional logic. A binary Boolean function, a Boolean function with two arguments, can be described by one out of sixteen canonical formulas.

Oct 122017