Individual #non-Euclidean_geometry  geometry based on axioms different from Euclid's
  >part of:  geometry  the pure mathematics of points and lines and curves and surfaces
  >part:  hyperbolic_geometry  a non-Euclidean geometry in which it is assumed that through any point there are two or more parallel lines that do not intersect a given line in the plane
  >part:  elliptic_geometry__Riemannian_geometry  a non-Euclidean geometry that regards space is like a sphere and a line is a great circle

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