With no explanation, label text_A→text_B with either "not_related" or "related".
text_A: The Himalayas has over fifty mountains.
text_B: David Lucas -LRB- 1802 -- 1881 -RRB- was an English mezzotint engraver , best known for his association with John Constable .. mezzotint. mezzotint. John Constable. John Constable
not_related.