Search All of the Math Forum:
Views expressed in these public forums are not endorsed by
NCTM or The Math Forum.


LudovicoVan
Posts:
4,065
From:
London
Registered:
2/8/08


Re: A flaw in modern axiomatic geometry?
Posted:
May 1, 2013 4:23 PM


"Butch Malahide" <fred.galvin@gmail.com> wrote in message news:cea27a9c4ebb43ac99a0003daee679e4@r3g2000yqe.googlegroups.com... > On Apr 30, 7:14 pm, "Julio Di Egidio" <ju...@diegidio.name> wrote: >> >> As I gather it, what he says is that from Playfair's axiom and his >> litetriangle axiom one can prove Pasch's axiom. But the two former >> axioms >> are common to Euclidean and nonEuclidean geometry, while Pasch's axiom >> is >> Euclidean only: hence the contradiction. > > Playfair's axiom? Isn't that the one that says that only one parallel > to a given line can be drawn through a given point not on the line? > That axiom is common to Euclidean and nonEuclidean geometry?
I had misread. Thank you and David Hartley for the feedback, after more reading I see he had nailed it since the beginning.
Julio



