History[edit source | editbeta]
In 1795 John Playfair published an alternative, more stringent formulation of Euclid's parallel postulate, which is now called Playfair's axiom; though the axiom bears Playfair's name, he did not create it, but credited others, in particular William Ludlam, with the prior use of it.[5]However, Proclus (410–485 A.D.) clearly makes the statement in his commentary on Euclid I.31 (Book I, Proposition 31)[6]
Relation with Euclid's fifth postulate[edit source | editbeta]