This is the Coq formalization and soundness proof for an input/output
verification approach. See
  https://people.cs.kuleuven.be/~willem.penninckx/input-output-verification/

Note: This version does not yet support non-termination in the proof rules
      (but it is supported in the step rules).

To make Coq check the soundness proof:
  1. Install Coq
  2. Run
       ./configure
  3. Run
       make


