THE THEOREM OF FINE AND WILF FO R RELATIONAL PERIODS

We con sid er relat ion al p e rio d s, wh ere t h e relat ion is acompat ibility r elat ion on wor ds i nduced by a relat ion on letters. Weprove a variant of the theorem of Fin e and Wilf for a (pure) p erio d an da r elation al p erio d