The file "peq.k" includes the K implementation of the circular coinduction proof system for the program equyivalence, defined as a bisimulation. The theory can be found in

Program Equivalence by Circular Reasoning
Dorel Lucanu   Vlad Rusu  
IFM,   Lecture Notes in Computer Science,   362-377,   2013  

The compilation of the verifier must be done with the following command:
  kompile peq.k

Then you can check equivalence formulas. You can fins several examples of such formulas in the subfolder proframs. These formulas are executed as regular programs. Here is an example:
  krun programs/for-while.peq

If the cell <goals> in the final configuration includes only "success" item, then formula holds.
If the execution time is too long, then very probably the derivation is infinite, which is a sign that the formula does not hold.



