Re: modal logic's meta axiom

2012-06-13 Thread Bruno Marchal
On 13 Jun 2012, at 00:38, Russell Standish wrote: On Tue, Jun 12, 2012 at 08:17:38PM +0200, Bruno Marchal wrote: On 12 Jun 2012, at 00:47, Russell Standish wrote: On Thu, Jun 07, 2012 at 01:33:48PM +0200, Bruno Marchal wrote: In fact we have p/p for any p. If you were correct we would

Re: modal logic's meta axiom

2012-06-13 Thread meekerdb
On 6/13/2012 12:14 AM, Bruno Marchal wrote: On 13 Jun 2012, at 00:38, Russell Standish wrote: On Tue, Jun 12, 2012 at 08:17:38PM +0200, Bruno Marchal wrote: On 12 Jun 2012, at 00:47, Russell Standish wrote: On Thu, Jun 07, 2012 at 01:33:48PM +0200, Bruno Marchal wrote: In fact we have

Re: modal logic's meta axiom

2012-06-12 Thread Bruno Marchal
On 12 Jun 2012, at 00:47, Russell Standish wrote: On Thu, Jun 07, 2012 at 01:33:48PM +0200, Bruno Marchal wrote: In fact we have p/p for any p. If you were correct we would have []p for any p. This is what I thought you said the meta-axiom stated? How else do we get p/[]p for Kripke

Re: modal logic's meta axiom

2012-06-12 Thread Russell Standish
On Tue, Jun 12, 2012 at 08:17:38PM +0200, Bruno Marchal wrote: On 12 Jun 2012, at 00:47, Russell Standish wrote: On Thu, Jun 07, 2012 at 01:33:48PM +0200, Bruno Marchal wrote: In fact we have p/p for any p. If you were correct we would have []p for any p. This is what I thought you

Re: modal logic's meta axiom

2012-06-11 Thread Russell Standish
On Thu, Jun 07, 2012 at 01:33:48PM +0200, Bruno Marchal wrote: In fact we have p/p for any p. If you were correct we would have []p for any p. This is what I thought you said the meta-axiom stated? How else do we get p/[]p for Kripke semantics? --

modal logic's meta axiom

2012-06-07 Thread Russell Standish
Bruno, I've deleted the previous thread, so I've started a new one on modal logic's metaaxiom. 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)? Could this also be written p --- ? []q

Re: modal logic's meta axiom

2012-06-07 Thread Bruno Marchal
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