[isabelle-dev] [isabelle] Tiny minor backward-compatible changes to IFOL
nipkow at in.tum.de
Mon Apr 27 13:28:45 CEST 2020
On 27/04/2020 13:08, Lawrence Paulson wrote:
> I have only recently proved a result of this sort, and thinking back, the need to write out
> !x y. P x & P y —> x=y
> has always been one of my pet bugbears.
That does indeed crop up from time to time.
> I don’t think a fancy symbol is needed for something that will be fairly lightly used however.
>> On 27 Apr 2020, at 11:58, Tobias Nipkow <nipkow at in.tum.de> wrote:
>> I don't recall feeling the need for it, although I may just be too used to what we have to conceive of notions beyond. But I have (almost) never seen it anywhere else. There are of course the counting quantifiers.
>> Having said that, I wouldn't object to an "at most one" quantifier provided it has a decent syntax. See https://math.stackexchange.com/questions/1205464/quantifier-for-there-is-at-most-one
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