With no explanation, label text_A→text_B with either "not_related" or "related".
text_A: Istanbul is a world center.
text_B: Pelargoderus sijthoffii is a species of beetle in the family Cerambycidae .. Cerambycidae. Cerambycidae. Pelargoderus. Pelargoderus. beetle. beetle. It was described by Ritsema in 1901 .
not_related.