Proof checking

Proof term

A term whose type is the proposition it proves.

Definition

Proof term

Under the propositions-as-types interpretation, a proof term is a value accepted at the type representing a proposition.

The kernel infers or checks the term's type. If that type matches the theorem statement, the term proves the theorem under the calculus and environment.

01

Example

A function taking proofs of P and Q and returning the proof of P is a proof of P ∧ Q → P.

02

Important distinction

A tactic script is a program that may construct a proof term; it is not necessarily the object the kernel finally checks.

After reading this article, you should be able to

  • Define Proof term in the sense used on this site.
  • Read a small proof term as both a program and a proof.