With no explanation, label text_A→text_B with either "not_related" or "related".
text_A: The Catalyst came off of A Thousand Suns as the album's first single.
text_B: Mary Amelia 'Em ily Mary ' Cecil , 1st Marchioness of Salisbury -LRB- 1750 -- 1835 -RRB- , was an English aristocrat , Tory political hostess and sportswoman .
not_related.