  Existence results for Hilbert's problem 13th mean that any equation
constructed by continue functions can be given solution represented as a
superposition of continue functions of one variable or of continue functions of
two variables. Constructive results for discrete functions are given in this
paper that any equation constructed by functions called discrete 3 function for
which field of definition is a set containing only -1,0,1 can be given solution
represented as a superposition of discrete 3 functions of one variable or of
two variables. Formula solution for equation with parameterized operations can
be given after introducing four special operators being correspondence among
known operations and new operations. These results can be extended to discrete
operators and operator equations constructed by them.
