isabelle extreme This opens a theory file with the extension .ext . Here’s a minimal example:
Also known as (EXperimental TRansformational Equational Mathematics Engine), this is not a new front-end or library. It is a radically stripped-down meta-logic – the absolute minimal core needed to perform interactive proofs within the Isabelle framework.
No – and that’s the point. isabelle-extreme is intentionally useless for application-scale verification. It lacks data types, recursion schemes, and any form of automation. Trying to prove 1+1=2 requires dozens of manual rewrite steps. However, as a and kernel sanity check , it is invaluable. isabelle-extreme
Beyond the Mainland: Exploring isabelle-extreme , the Minimalist Core of Interactive Theorem Proving
theory Scratch imports Main begin (* Define addition via fixed point *) definition add :: "nat ⇒ nat ⇒ nat" where "add ≡ fix (λadd n m. if n = 0 then m else add (n-1) (m+1))" isabelle extreme This opens a theory file with the extension
If you have Isabelle installed (2023 or later), you can launch isabelle-extreme directly from the command line:
(* Prove a simple property manually – no automation! ) lemma add_zero: "add 0 m = m" unfolding add_def by (rule fix_eq) ( primitive rule only *) No – and that’s the point
If you’ve ever wondered, “What is the absolute minimum logic needed to build an ITP?” – isabelle-extreme is your answer.
