Re: [HM] Re: porisms
Claire Czinczenheim (c.czinczenheim@mail.ac-lille.fr)
Thu, 28 Jan 1999 15:59:37 +0100
In classical Greek geometry, a diorism is in a problem, a condition
to be fulfilled so that the problem can be solved; for instance, in
Euclid's first book, "given three straight lines, to construct a
triangle"; the diorism is "it is necessary that any two of the straight
lines are always longer that the last one"; the necessity of this
diorism was proved before in a theorem, as often happens in a theorem,
the diorism is the second part of the demonstration, that repeats the
law to be proved, but not in its general form : Euclid I 5: "in isosceles
triangles, the angles at the base are equal"; the diorism is: let ABC be
an isosceles triangle, with side AB equal to side AC, etc" I quote
approximately, as I do not have the text with me.
Claire
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> De : Jim Propp <propp@math.mit.edu>
> A : historia-matematica@chasque.apc.org
> Objet : [HM] Re: porisms
> Date : mercredi 27 janvier 1999 23:45
>
> While we're on the subject: Where can I learn what a "diorism" is?
>
> Thanks,
>
> Jim Propp
> Department of Mathematics
> University of Wisconsin