Parallel hyperbolic lines
= Parallel hyperbolic lines
Two distinct <hyperbolic lines> are parallel, in the limiting-parallel convention, when they do not intersect in the <hyperbolic plane> and have exactly one common <ideal endpoint>. In the <upper half-plane model>, distinct vertical lines are parallel, sharing infinity. Disjoint lines with no common <ideal endpoint> are instead <ultraparallel hyperbolic lines>; only these have a <common perpendicular of ultraparallel hyperbolic lines>.