On Thu, May 24, 2012 at 03:42:15PM +0200, Bruno Marchal wrote: > > But "a => Ba" is a valid rule for all logic having a Kripke > semantics. Why? Because it means that a is supposed to be valid (for > example you have already prove it), so a, like any theorem, will be > true in all worlds, so a will be in particular true in all worlds > accessible from anywhere in the model, so Ba will be true in all > worlds of the model, so Ba is also a theorem.
I still don't follow. If I have proved a is true in some world, why should I infer that it is true in all worlds? What am I missing? -- ---------------------------------------------------------------------------- Prof Russell Standish Phone 0425 253119 (mobile) Principal, High Performance Coders Visiting Professor of Mathematics hpco...@hpcoders.com.au University of New South Wales http://www.hpcoders.com.au ---------------------------------------------------------------------------- -- 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.
