23 Aug
2002
23 Aug
'02
9:17 a.m.
On Wed, 21 Aug 2002, Galchin Vasili wrote:
Dear CT Community,
I am new to Topos theory. Is it true that Hom[1->omega] in a topos defines a Heyting algebra?
Yes
If so, please give me a reference where this is proved.
In almost any book on the subject: e.g. 5.13 in my own "Topos Theory", Theorem 5.6.4 in "Toposes, Triples and Theories" by Barr and Wells, Theorem IV 8.1 in "Sheaves in Geometry and Logic" by Mac Lane and Moerdijk, and Lemma A1.6.3 in "Sketches of an Elephant". Peter Johnstone 23-Aug-2002 16:18:15 -0300,2285;000000000001-00000000