Parallelism axiom

The axiom defining the relationship of parallelism in various geometries. See Parallel straight lines; Fifth postulate.

#### References[edit]

[a1] |  D. Hilbert, "Grundlagen der Geometrie" , Teubner, reprint (1968)

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[a2] |  H.S.M. Coxeter, "Introduction to geometry" , Wiley (1969) pp. 185–186; 396–404