On 07 Jun 2012, at 01:58, Russell Standish wrote:

Bruno, I've deleted the previous thread,

?

`It is possible to delete thread? Including my posts? That should not`

`be possible.`

so I've started a new one on modal logic's "metaaxiom".

OK.

IIUC, if I have p (true in a world), and by dint of whatever convoluted steps, I have p --, q then it is also true that []q (q must be true in all worlds)?

`Not necessarily. It can depend on what axioms are used on "p/q". Nor`

`is it necessary that you get p -> q, nor p-> []q. Modal logic does not`

`obey to the deduction theorem.`

`In fact we have p/p for any p. If you were correct we would have []p`

`for any p.`

Could this also be written <>p --- ? []q

I don't see any reason for this. Bruno http://iridia.ulb.ac.be/~marchal/ -- You received this message because you are subscribed to the Google Groups "Everything List" group. To post to this group, send email to everything-list@googlegroups.com. To unsubscribe from this group, send email to everything-list+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/everything-list?hl=en.