This is a simple program which aims to prove that the program C = (A-B)*2 is implemented correctly. The specified "errors" in implementation of this program are the use of arithmetic operators, where they could be potentially be either +, -, / or * instead of the two in the program above.
From these potential incorrect implemtnations, the two scripts in this repository find and test values for inputs A and B which can prove that the program has been implemented correctly and that any other operators have not been used instead.
bisection_AB.php loops through a range of values for input B and identifies values for A in which the test case would fail.
ValueTester.php tests two inputs A and B and determines if they are a suitable concrete test case.