Stream: Archive Mirror: Isabelle Users Mailing List

Topic: [isabelle] THE - equality


view this post on Zulip Email Gateway (Aug 19 2022 at 14:20):

From: "Roger H." <s57076@hotmail.com>
Hello,

how can i prove

(THE x. x + 1 = 3) = 2 ?

After

"apply (rule the_equality, simp)"

i get:

⋀x. x + 1 = 3 ⟹ x = 2

I think i have to prove that the solution is unique.
how do i continue?

Thank you!

view this post on Zulip Email Gateway (Aug 19 2022 at 14:21):

From: Lawrence Paulson <lp15@cam.ac.uk>
You need a type constraint:

lemma "(THE x::int. x + 1 = 3) = 2"
by auto

Otherwise, Isabelle doesn’t know what sort of numbers you are talking about. Numerals are polymorphic.

Larry Paulson

view this post on Zulip Email Gateway (Aug 19 2022 at 14:21):

From: "C. Diekmann" <diekmann@in.tum.de>
What is the type of x? Did you try x::nat?


Last updated: Nov 21 2024 at 12:39 UTC