[FOM] 336:Undecidability/Euclidean geometry/2
pax0 at seznam.cz
Thu Apr 30 07:23:33 EDT 2009
Harvey Friedman wrote:
> An integral line system is a finite set of rational lines whose
> intersection points have integer coordinates.
> We say that f is an equivalence between integral line systems S,T if
> and only if f is a bijection from S onto T such that for any
> L_1,...,L_k in S,
I think, that here is missing some continuity condition on f, as is in the original formulation.
What happens with theorems 1 and 2 if we require moreover that the
bijection from S onto T maps every line of S _analytically_ onto a
line of T?
Thank you, Jan Pax
> L_1,...,L_k have a common point if and only if f(L_1),...,f(L_k) have
> a common point.
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