With no explanation, label text_A→text_B with either "not_related" or "related".
text_A: William Shakespeare collaborated with others.
text_B: In mathematics , separation of variables -LRB- also known as the Fourier method -RRB- is any of several methods for solving ordinary and partial differential equations , in which algebra allows one to rewrite an equation so that each of two variables occurs on a different side of the equation .. mathematics. mathematics
not_related.