Kindly comments on Mental Context for Model Theory - Less Wrong

49 Post author: So8res 30 October 2013 06:35AM

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Comment author: Anders_H 25 April 2015 06:21:19PM 5 points [-]

I'm not sure why this comment is being downvoted - perhaps because of the tone - but the content in it is true

The definition of parallel lines is essentially "lines that don't intersect". We therefore do not need an axiom to show that if two lines are parallel, the do not intersect - this just follows from the definition.

The fifth postulate says that for every line L and point P outside of L, the parallel line L' through P is unique (Existence of L' follows from axioms 1 through 4)

Comment author: RichardKennaway 25 April 2015 10:56:18PM 5 points [-]

I'm not sure why this comment is being downvoted

This:

This is bad and you should feel bad.