出典:Wikipedia
出典:『Wikipedia』 (2011/05/12 21:26 UTC 版)
In neutral geometry, there may be many lines parallel to a given line l at a point P, however one parallel may be closer to l than all others. Thus it is useful to make a new definition concerning parallels in neutral geometry. If there is a closest parallel to a given line it is known at the limiting parallel. The relation of limiting parallel for rays is an equivalence relation, which includes the equivalence relation of being coterminal.