Very nice. One suggestion, I found the abstract and introduction difficult to understand, and only got the real point by page 3. I would add something clearer

Very nice. One suggestion, I found the abstract and introduction difficult to understand, and only got the real point by page 3. I would add something clearer in the abstract and/or introduction, such as: "Static analysis is used to construct alternative versions of the program, that give identical outputs for a given subset of inputs I. The alternative programs are compiled and executed, and we test whether they do actually give the same outputs as the original program, on the input data I. By restricting to a subset I of inputs, a greater variety of alternatives can be produced, than if the alternatives had to be identical to the original program for all inputs."