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Re: Using classes instead of sets
Posted:
Mar 30, 2013 10:35 AM
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On Fri, 29 Mar 2013 18:24:47 -0400, Shmuel (Seymour J.) Metz
<spamtrap@library.lspace.org.invalid> wrote:
>In <f8ral8lndkanp4gd70pu1fmblq4g912o74@4ax.com>, on 03/29/2013
> at 06:07 AM, quasi <quasi@null.set> said:
>
>>There are certain concepts for which sets are inadequate and classes
>>come to the rescue. For example, we need the class concept if we
>>want to define an equivalence on the collection of all groups, since
>>that collection is not a set.
>
>There's no such set in ZFC, but there are set theories in which it
>exists aqnd is a set.
Oh? For example?
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