Re: Open formulas in the empty domain
- From: "Michael De" <mikejde@xxxxxxxxx>
- Date: 23 Oct 2005 19:48:32 -0700
In fact, this doesn't make any sense. Suppose that all open formulas
are valid in {} and there is no restriction on MP. Then from f(x) v
~f(x) and [f(x) v ~f(x)] -> Ex[f(x) -> ~f(x)] we may infer Ex[f(x) ->
~f(x)] which is false in {} unless we interpret Ex in some nonstandard
way. So what is Leblanc talking about?
.
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