leanprover / theorem_proving_in_lean4

Theorem Proving in Lean 4
https://leanprover.github.io/theorem_proving_in_lean4/
Apache License 2.0
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propositions_and_proofs: use builtin `implies` connective #81

Closed dijkstracula closed 3 months ago

dijkstracula commented 1 year ago

Defining the Implies function whilst hiding it from the rendered document makes following the chapter difficult, as the reader expects that it is a built-in alongside the other propositional connectives.

This patch also makes explicit the definition for Proof for the same reason: without the definition one can't follow along in an editor. I wonder if for pedagogical purposes defining it as an axiom rather than a structure is less opaque?