11 Jul
1997
11 Jul
'97
8:56 p.m.
> f(a) & a = f(true) & a > > I wonder whether anyone has noticed this formula before? Similar formulas and their analogs in intuitionistic second-order propositional calculus are discussed in my paper in the Annals Pure Appl. Logic 27 (1984) 155-164. That paper was motivated by Higgs's observation that every monic Omega -> Omega in a topos is an involution, see Peter Johnstone's paper "Automorphisms of Omega" in Alg. Universalis 9 (1979) 1-7. Andre Scedrov