Dear Bruno, Thank you for your reply.

You wrote that 'B is valid in the frames where "result of experience" can be verified or repeated'. Can you be more explicit because I cannot see the relation with the fact that the accessibility relation is reflexive and symmetric (a proximity relation). I know that in the Provability Logic GL, []A is to be read as "A is provable". (I write [] for Box). "A is provable" does not mean that I have an explicit proof of A. Indeed, in the context of the first-order arithmetic, "A is provable" only means that "there exists a number which is a code of a proof of A". I also know that in S4, []A is to be read as "A is constructively provable": S4, which was shown by Sergei Artemov to be a forgetful projection of the Logic of Proofs LP. Could we also interpret B also in terms of some kind of provability? _____________________________________________________________________________ Ne gardez plus qu'une seule adresse mail ! Copiez vos mails vers Yahoo! Mail http://mail.yahoo.fr --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Everything List" group. To post to this group, send email to [EMAIL PROTECTED] To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/everything-list?hl=en -~----------~----~----~----~------~----~------~--~---