I am trying to find an example axiom in Coq of something like the line axiom in geometry: If given two points, there exist a line between those two points. I would like to see how this could be defined in Coq. Inherently choosing this simple line axiom to see how something very primitive is defined, because I'm having a hard time defining it outside natural language.
Specifically, I have seen these two axioms and would like to know how in Coq to define both:
- Any two distinct points always determine a line
- Any two distinct points of a line determine this line uniquely
It almost seems like you can merge them into one definition, so I would like to see syntactically and semantically how to write this in Coq.
I don't know how to write Coq really, just looking to see how they do it. But if I were to try it seems like this:
Axiom line : forall ptA:Point ptB:Point, line ptA ptB.
But that needs a Line and a Point object.
Axiom line : forall ptA ptB, line ptA ptB.
Definition Line ptA ptB -> (...) No idea.
Definition Point ...