It is a bit of a strange theorem. I see that it is in Glauco's mathbox (and referenced a few times), and both the proof and the uses can be simplified using ovex, but perhaps there is something that they were trying to avoid (not axioms, the axiom list is a strict subset with the new proof). Perhaps they can chime in here.
On Wed, Apr 21, 2021 at 9:48 PM Jim Kingdon <[email protected]> wrote: > On 4/21/21 5:37 PM, Kyle Wyonch wrote: > > > I was wondering if this shortening [of cnfex] was valid > > Short answer is, yes it is valid. > > The longer answer is that set.mm defines a function evaluated outside > its domain to be the empty set which is why > http://us.metamath.org/mpeuni/fvex.html does not have any conditions. > > By contrast, iset.mm does not have the ability to do quite this, so > instead cnfex would need to use > http://us.metamath.org/ileuni/funfvex.html or one of the other > alternatives under fvex at http://us.metamath.org/ileuni/mmil.html#setmm > > There is some discussion of this in the "undefined results" section of > http://us.metamath.org/mpeuni/conventions.html and > http://us.metamath.org/ileuni/conventions.html > > -- > You received this message because you are subscribed to the Google Groups > "Metamath" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To view this discussion on the web visit > https://groups.google.com/d/msgid/metamath/c36661f8-ac06-7264-2dd8-d95a1cb1b41f%40panix.com > . > -- You received this message because you are subscribed to the Google Groups "Metamath" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/metamath/CAFXXJSuXKjv2QmHLVpQwJ1RHLEgPJhhLS6V28AFY4wg2FrsUKw%40mail.gmail.com.
