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Re: Cardinals as Equivalence class?

Subject: Re: Cardinals as Equivalence class?
From: "MoeBlee"
Date: 31 Oct 2006 10:16:16 -0800
Newsgroups: sci.math
zuhair wrote:
> What is Uc?

By the union axiom, for any c, there exists the set of all members of
members of c. That set is Uc. Put another way:

x e Uc <-> Ez(zec & xez).

> now if c for example is c= { a,b,c}
>
> is Uc= a U b U c.

Notice that U is a unary operation. But from the union axiom and
pairing axiom, we can define a binary operation too.

x u y = U{x y}.

So, yes, if c = {x y z}, the Uc = x u y u z.

When are you going to get those books you said you'd get? To start, the
Kalish, Montague, and Mar logic book.

MoeBlee


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