With no explanation, label text_A→text_B with either "not_related" or "related".
text_A: Wyatt Earp served as a saloon-keeper.
text_B: In mathematics , a recurrence relation is an equation that recursively defines a sequence or multidimensional array of values , once one or more initial terms are given  : each further term of the sequence or array is defined as a function of the preceding terms .. mathematics. mathematics. equation. equation. recursively. recursion. sequence. sequence. function. Function ( mathematics ). The term difference equation sometimes -LRB- and for the purposes of this article -RRB- refers to a specific type of recurrence relation .. equation. equation. difference equation. #Relationship to difference equations narrowly defined. However , `` difference equation '' is frequently used to refer to any recurrence relation .. equation. equation. difference equation. #Relationship to difference equations narrowly defined
not_related.