With no explanation, label text_A→text_B with either "not_related" or "related".
text_A: Alex Sharp is an English actor.
text_B: The Dee Bridge disaster was a rail accident that occurred on 24 May 1847 in Chester with five fatalities .. Chester. Chester. rail accident. rail accident. It revealed the weakness of cast iron beam bridges reinforced by wrought iron tie bars , and brought criticism of its designer , Robert Stephenson , son of George Stephenson .. Robert Stephenson. Robert Stephenson. George Stephenson. George Stephenson
not_related.