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## Re: [ontolog-forum] Truth

 To: ontolog-forum@xxxxxxxxxxxxxxxx John F Sowa Tue, 24 Jul 2012 09:10:14 -0400 <500E9EB6.2070706@xxxxxxxxxxx>
 ```Dear Matthew,    (01) You can think of a context as a container for one or more propositions. McCarthy's 'ist' operator is an abbreviation for "is true in". Note that the preposition 'in' suggests a container.    (02) PH > I asked John [McCarthy] about his basic logical construct 'ist', > written as ist(c, p) > > and read as meaning "p is true in the context c". The question was, is > the 'p' in this formula a sentence or a proposition? It is *written* in > the McCarthy/Guha/Makarios context logics as a sentence; but to my > delight, John said it was a proposition. Which is exactly what it is in > the IKL way of writing this as a logical relation between two things, a > context and a proposition.    (03) MW > How is ist different from simple inference? i.e. from > If c then p.    (04) An if-then statement of the form "If c then p" is a sentence that relates two other sentences c and p.    (05) The statement ist(c,p) -- or as Pat and I would prefer to write it ist(c, (that p)) -- relates a context c to sentence p. It does not say that c implies p. Instead, it says that p is true *in* c.    (06) To get the effect of an implication, you could use the following axiom to specify a kind of context logic:    (07) If (p implies q) then (ist(c,p) implies ist(c,q)).    (08) This axiom says that if p is true in a context c, then any sentence in the deductive closure of p is also true in c.    (09) Without this axiom (or something similar), 'ist' would not have the effect of an implication.    (010) For more discussion of these issues, see Pat's article about IKL:    (011) http://www.ihmc.us/users/phayes/IKL/GUIDE/GUIDE.html#ContextsModalities    (012) Or see my article from the AAAI symposium on contexts:    (013) http://www.jfsowa.com/pubs/fs95.pdf    (014) John    (015) _________________________________________________________________ Message Archives: http://ontolog.cim3.net/forum/ontolog-forum/ Config Subscr: http://ontolog.cim3.net/mailman/listinfo/ontolog-forum/ Unsubscribe: mailto:ontolog-forum-leave@xxxxxxxxxxxxxxxx Shared Files: http://ontolog.cim3.net/file/ Community Wiki: http://ontolog.cim3.net/wiki/ To join: http://ontolog.cim3.net/cgi-bin/wiki.pl?WikiHomePage#nid1J    (016) ```
 Current Thread Re: [ontolog-forum] Truth, (continued) Re: [ontolog-forum] Truth, Aldo Gangemi Re: [ontolog-forum] Truth, Gary Berg-Cross Re: [ontolog-forum] Truth, David Eddy Re: [ontolog-forum] Truth, Obrst, Leo J. Re: [ontolog-forum] Truth, Pat Hayes Re: [ontolog-forum] Truth, doug foxvog Re: [ontolog-forum] Truth, Pat Hayes Re: [ontolog-forum] Truth, John F Sowa Re: [ontolog-forum] Truth, Pat Hayes Re: [ontolog-forum] Truth, Matthew West Re: [ontolog-forum] Truth, John F Sowa <= Re: [ontolog-forum] Truth, Pat Hayes Re: [ontolog-forum] Truth, John F Sowa Re: [ontolog-forum] Truth, Pat Hayes Re: [ontolog-forum] Truth, John F Sowa Re: [ontolog-forum] Truth, John Bottoms Re: [ontolog-forum] Truth, Pat Hayes Re: [ontolog-forum] Truth, John F Sowa Re: [ontolog-forum] Truth, Kingsley Idehen [ontolog-forum] Context [was: Truth], doug foxvog Re: [ontolog-forum] Truth, Avril Styrman