1 research outputs found
Formalizing Computability Theory via Partial Recursive Functions
We present an extension to the library of the Lean theorem
prover formalizing the foundations of computability theory. We use primitive
recursive functions and partial recursive functions as the main objects of
study, and we use a constructive encoding of partial functions such that they
are executable when the programs in question provably halt. Main theorems
include the construction of a universal partial recursive function and a proof
of the undecidability of the halting problem. Type class inference provides a
transparent way to supply G\"{o}del numberings where needed and encapsulate the
encoding details.Comment: 16 pages, accepted to ITP 201