FOM: well-founded extensional relations

[Thomas Forster]

Holmes says of the wellfounded extensional relation interpretation:
>I don't think any of this is terribly original.  I know about it because
it is the standard technique for attempting to interpret ZFC in NF and
related theories.

I think one should probably credit Roland Hinnion with this.
Granted, it's not terribly difficult, but it is rather nice
and he was the first person to think of it (wasn't he?)