Lean formalization of Eric Hehner’s aPToP, plus tools that make the book’s calculational proofs and programming notation runnable.
Three-pane assistant for calculational proofs: proof, context, suggestions — Lean kernel, no Mathlib. Book exercises under Examples.
Run aPToP programming notation in the browser. Editable editor with symbols like ∧ ∨ ⇒ ⊤; Run posts to a loopback runner.
Interpreter demos with syntax highlighting — insert book symbols (∧ ∨ ⇒ ≡ × · ′ …) from the Symbols button.
Static home from deploy/aptop/site/; /netty/ proxies to
a loopback Node + Lean Netty kernel; /interp/ is an editable
runner (binary may be stubbed if Mathlib build is unavailable on this box).
Deploy notes: deploy/aptop/deploy.md in
tangentproofs/laptop.
Canonical book: hehner.ca/aPToP
· course: hehner.ca/FMSD
(U of T mirrors linked above).