If I have two finite sets and and a set of conditions of the form for some , , and I want to find functions that satisfy all these condition, then ...

A generalisation of graph colouring problems – mathoverflow.net
rimu

If I have two finite sets V and C and a set of conditions of the form f(u)=f(v) for some u, v∈V, and I want to find functions f:V→C that satisfy all these condition, then ...