key-abstract-contracts (based on KeY 2.1) ====================== This version of the KeY verification system (http://key-project.org) can be used to evaluate abstract method contracting. (Works with Java 8 by running key.sh/key.bat on Linux or Windows accordingly.) The idea is to only substitute abstract placeholders for method calls instead of the concrete requires, ensures, and assignable clauses. Such a proof is called a partial/incomplete/cached/abstract proof (with abstract placeholders), which leads to only first-order open obligations. To create such a proof, load a file/directory in which some methods are annotated with @requires_abs, @ensures_abs, @assignable_abs and/or @def. (@defs can be omitted at this point, as they provide the concrete clauses which are only filled in at a later step.) Then right-click on 0: OPEN GOAL and select Strategy macros > Finish abstract proof part (or press Shift+X) - DO NOT use the green start button for this. The resulting partial proof can be saved as a .proof file as usual. To complete a partial proof later on (possibly with different concrete instantiations), again load the file/directory (now the @defs MUST be present). When KeY is ready to prove (0: OPEN GOAL), run File > Reuse proof and select the .proof file saved above. The partial proof is replayed. Now simply click the green start button to complete the proof with the given @defs. (Note that for some of the given examples, setting "Arithmetic treatment" to "Model Search" may be required.) This KeY version can be used to reproduce the results of this paper: https://link.springer.com/chapter/10.1007/978-3-662-45231-8_9