[isabelle-dev] [isabelle] Tiny minor backward-compatible changes to IFOL

Lawrence Paulson lp15 at cam.ac.uk
Sun May 10 18:56:07 CEST 2020

It would be great if we could finalise the proposal for the uniqueness quantifier.

I was planning to do this in a strictly upward compatible way, so with no implications for the existing quantifier notations and no changes to existing theorems, but a few new theorems. For that I think that "∃⇩≤⇩1” is a standard notation and works well enough. The notation “∃!” for unique existence is also absolutely standard and surely does not need to change.


> On 2 May 2020, at 18:17, Makarius <makarius at sketis.net> wrote:
> In contrast, the other idea "∃⇩≤⇩1" from Mathoverflow would come out for Ex1
> as "∃⇩=⇩1" or "∃⇩1", and thus introduce an incoherence of notation.

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