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Issue: SUBTYPEP-EMPTY-NIL (Version 1)
- To: KMP@STONY-BROOK.SCRC.Symbolics.COM, firstname.lastname@example.org
- Subject: Issue: SUBTYPEP-EMPTY-NIL (Version 1)
- From: Glenn S. Burke <gsb@ALDERAAN.SCRC.Symbolics.COM>
- Date: Wed, 8 Feb 89 23:14 EST
- Cc: CL-Cleanup@SAIL.Stanford.EDU
- In-reply-to: <890208093740.1.KMP@BOBOLINK.SCRC.Symbolics.COM>
Date: Wed, 8 Feb 89 09:37 EST
From: Kent M Pitman <KMP@STONY-BROOK.SCRC.Symbolics.COM>
Sorry, but this is a serious attempt to get a clarification.
I don't see that any criterion has been advanced by CLtL for believing
NIL T is any better or worse than T T. If CLtL is clear and I've just
missed the passage, by all means cite it. Alternatively, you may have some
personal criterion which you'd like us to buy into. If you propose that
criterion and no one contests, I'll be quite happy to see the issue
turn out to resolved by a non-controversial vote.
NIL T leads to a situation of functionally equivalent forms of the "empty"
type set not being equivalent under (and (subtypep x y) (subtypep y x)).
I believe that to be a good argument for T T, whether or not CLtL even
hints that this should be the case.