With no explanation, label text_A→text_B with either "not_related" or "related".
text_A: José María Chacón died in 1796.
text_B: An optical system with astigmatism is one where rays that propagate in two perpendicular planes have different foci .. optical system. optical system. rays. ray ( optics ). planes. Plane ( mathematics ). foci. focus ( optics ). If an optical system with astigmatism is used to form an image of a cross , the vertical and horizontal lines will be in sharp focus at two different distances .. optical system. optical system. cross. cross. The term comes from the Greek α - -LRB- a - -RRB- meaning `` without '' and στιγμα -LRB- stigma -RRB- , `` a mark , spot , puncture '' .. Greek. Greek language
not_related.