Introduction
The aim of this study is studying coloring graph by colorable functions and explicating the conditions and their performance on known graphs. Fixing barriers of using the method such as the conditions of creating a function, defining the type of functions, etc. are among the main purposes of the study. To this end, at first, colorability of graphs is defined and then its elements are analyzed.
Definition: Let f : X → X be a graph without fixed point. f is colorable with k colors, if there is