Representation of Three-Valued Boolean Functions
This Demonstration displays three-valued Boolean functions of arguments. If , the disjunctive normal form (DNF) of a function is also given. If , a random function is given.
A three-valued logic function of arguments is represented by . There are such functions; if , there are nine and if , there are 19,683.
The roles of conjunction and disjunction are played by the functions and .
Define three functions for :
if and 0 otherwise.
Each function of arguments can be represented in disjunctive normal form (DNF):
where and the maximum is taken over all tuples with components from .
It follows that the constants 0, 1, 2 together with the functions , and form a basis for three-valued Boolean functions [2, pp. 245–246].
In 1936, SŁupecki [1, pp. 335–337] showed that all three-valued functions could be defined using implication and negation from Łukasiewicz three-valued logic plus the constant function called "tertium", 1.
In -valued logic, the Sheffer–Webb function (an analog of the Sheffer stroke function, NAND) forms a basis for -valued logic [2, p. 247].
 M. Gardner, Logic Machines, Diagrams and Boolean Algebra, New York: Dover Publications, 1968.
 S. G. Gindikin, Algebraic Logic in Problems (in Russian), Moscow: Nauka Publishers, 1972.
 J. SŁupecki, "The Full Three-Valued Propositional Calculus," Polish Logic 1920–1930, S. McCall (ed.), Oxford: Oxford University Press, 1967.