Re: self-sampling assumption is incorrect

From: Bruno Marchal <>
Date: Fri, 5 Jul 2002 19:54:27 +0200

Hi Wei Dai,

About books. Concerning the provability logics I always mentionned
the Boolos 1993 (or even his lovely lighter Boolos 1979), but I would
like to mention also the book "Self-reference and modal logic" by
Smorynski. The only problem is its very little caracters; I should go
to the occulist! :0 But he has a nice chapter on the algebraic models
of the provability logic: the so called diagonalisable algebras and
fixed point algebras. As you know the Z logics I got are so weak that
they loose (like G*) Kripke semantics or even Scott-Montague
(sort of topological) semantics. So we need some algebraic move.
Note that the G/G* story *begun* with those diagonalisable algebra
through the work of Magari (Italy).

But, perhaps more importantly at this stage I must recall the book
"Mathematics of Modality" by Robert Goldblatt. It contains fundamental
papers on which my "quantum" derivation relies. I mentionned it a lot
some time ago.
And now that I speak about Goldblatt, because of Tim May who dares
to refer to algebra, category and topos! I want mention that Goldblatt
did wrote an excellent introduction to Toposes: "Topoi". (One of the big
problem in topos theory is which plural chose for the word "topos". There
are two schools: topoi (like Goldblatt), and toposes (like Bar and
Wells). :)

Goldblatt book on topoi has been heavily attacked by "pure categorically
minded algebraist like Johnstone for exemple, because there is a remnant
smell of set theory in topoi. That is true, but that really help for an
introduction. So, if you want to be introduced to the topos theory,
Goldblatt Topoi, North Holland editor 19?(I will look at home) is
perhaps the one.


PS I get your questions. I will think a little bit before answering.
Thanks to Tim for Egan's exerp.
Received on Fri Jul 05 2002 - 10:51:44 PDT

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