On Mon, Sep 23, 2013 at 7:49 PM, Bruno Marchal <[email protected]> wrote: > > On 23 Sep 2013, at 12:41, Telmo Menezes wrote: > > On Sat, Sep 21, 2013 at 9:43 PM, Bruno Marchal <[email protected]> wrote: > > > On 21 Sep 2013, at 15:10, Telmo Menezes wrote: > > > On Fri, Sep 20, 2013 at 3:58 PM, Bruno Marchal <[email protected]> wrote: > > > > On 19 Sep 2013, at 16:51, Telmo Menezes wrote: > > > On Thu, Sep 19, 2013 at 4:31 PM, Bruno Marchal <[email protected]> > > > > If so, can't we say ~D~t and thus []t? > > > > Yes, []t is a theorem, of G and most modal logic, but not of Z! > > > > > > Isn't the only situation where ~Dt the one where this is no world? > > > > ~Dt, that is [] f, inconsistency, is the type of the error, dream, lie, and > > "near-death", or in-a-cul-de-sac. > > > Thus your interest in near-death experiences? > > > > Yes. And in all "extreme" altered state of consciousness. Those extreme > cases provide key information.
Can this information be recovered? For example, is a NDE that did not result in death, was it really a cul-de-sac? > > > > We should *try* to avoid it, but we can't avoid it without loosing our > > universality. > > > The consistent machines face the dilemma between security and lack of > > freedom-universality. With <>p = ~[] ~p, here are equivalent way to write > > it: > > > <>t -> ~[]<>t > > <>t -> <> [] f > > []<>t -> [] f > > > I don't understand how you arrive at this equivalence. > > > I use only the fact that (p -> q) is equivalent with (~q -> ~p) (the > contraposition rule, which is valid in classical propositional logic), and > the definition of <> p = ~[] ~p. I use also that ~~p is equivalent with p. > > Note that []p = ~~[]~~p = ~<> ~p. And, > > ~[]p = <> ~p > and > ~<>p = [] ~p > > Like with the quantifier, a not (~) jumping above a modal sign makes it into > a diamond, if it was a bo, and a box, if it was a diamond. > > > Starting from <>t -> ~[]<>t. But where does <>t -> ~[]<>t come from? > Contraposition gives ~~[]<>t -> ~<>t, and this > gives by above, []<>t -> []~t, which gives > []<>t -> []f (as ~t = f, and ~f = t). > > OK? Ok! > For the third one, starting from the first one again: <>t -> ~[]<>t, By > contraposition []<>t -> ~<>t , but ~<>t = []~t = [] f. > > OK? Ok! Thanks Bruno. My only problem now is the above. Telmo. > Bruno > > > > http://iridia.ulb.ac.be/~marchal/ > > > > -- > You received this message because you are subscribed to the Google Groups > "Everything List" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To post to this group, send email to [email protected]. > Visit this group at http://groups.google.com/group/everything-list. > For more options, visit https://groups.google.com/groups/opt_out. -- You received this message because you are subscribed to the Google Groups "Everything List" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at http://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/groups/opt_out.
