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## Re: [ontolog-forum] Prospects made into Customers and Vice Versa

 To: ontolog-forum@xxxxxxxxxxxxxxxx John F Sowa Mon, 26 Oct 2015 15:48:20 -0400 <562E8384.7030507@xxxxxxxxxxx>
 ```Tom,    (01) I hit SEND too soon.    (02) > What I think would be useful is a pair of terms to distinguish > "static sets" from "dynamic sets", and to relate the two concepts > in something like...    (03) No. That would be contrary to every version of set theory. For infinite sets, there must be some predicate that specifies membership in the set. For finite sets, you can always convert an enumeration to a monadic predicate:    (04) P(x) = x=x1 or x=x2 or x=x3 or ... or x-xN.    (05) Therefore, you can always say that for any set S, there exists a predicate P such that x is in S iff P(x).    (06) > (ii) A dynamic set is a temporal sequence of static sets    (07) It's much better to take a widely used term, such as 'type', which is common in computer science and other fields.    (08) In any programming language that specifies types, the definition of a type is a monadic predicate. During a computation, any type you specify would have a temporal sequence of sets at each step of the computation.    (09) This terminology would be easy to explain to any programmer, and most people who do any work in applied ontology also have some knowledge of programming.    (010) For the distinction between intension and extension, I recommend a short comment by Alonzo Church. He used it to talk about the intension/extension of functions, but you can also adapt it to talk about relations:    (011) http://www.jfsowa.com/logic/alonzo.htm    (012) John    (013) _________________________________________________________________ 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    (014) ```