Software Verification 1 Deductive Verification Prof. Dr. Holger Schlingloff Institut für Informatik der Humboldt Universität und Fraunhofer Institut für offene Kommunikationssysteme FOKUS

Folie 2 H. Schlingloff, Software-Verifikation I Parallel questions... Parallelism in Java and C?  Problems? Parallelism conceptually? Parallelism and nondeterminism?  Difference to „throwing a dice“? What are the atomic actions?  How to implement such a concept? Interleaving semantics? Deadlocks? Livelocks? Invariants for parallel programs? Owicki‘s rule?

Folie 3 H. Schlingloff, Software-Verifikation I Further Properties of Parallel Programs Termination: as in sequential case Fairness: b=1; {b=0; || while(b) skip} Mutual exclusion: always not both in c1 and c2  {while (1) {await(b) b=0; c1; b=1; nc1;} || while(1) {await(b) b=0; c2; b=1; nc2; }}  generalized: reader-writer-problem deadlock freedom, livelock freedom Two main classes of properties:  safety: all reachable states satisfy some invariant - “something bad never happens”  liveness: eventual reachability of states - “something good eventually happens”

Folie 4 H. Schlingloff, Software-Verifikation I Concurrency in VCC object invariants wrapping and unwrapping of objects

Folie 5 H. Schlingloff, Software-Verifikation I Introductory Example Revisited TBD

Folie 6 H. Schlingloff, Software-Verifikation I What you have learned Propositional and first-order logic in action SAT- and SMT-solving for program verification Doing a Hoare-style proof Proving more complex programs Dealing with various tools What does this help? for a later industrial career: awareness of software quality  need for specification, for an academic career: glimpse of research questions  many open problems, in theory, tooling, and applications  if you are looking for a thesis topic, just ask!

Folie 7 H. Schlingloff, Software-Verifikation I Outlook Software Verification 2 Automated Verification static analysis, abstract interpretation, abstraction refinement modeling and model checking temporal logic of programs NO direct continuation of this lecture  new topics, new participants very welcome  of course you have ideal prerequisites… Thursday 9-11 und 11-13, RUD25, Room  5 ECTS-Points, exercises and homework as usual

Folie 8 H. Schlingloff, Software-Verifikation I Exams Tue, , 10:00 -17:00 Register at Mrs. Heene (JvN 4.417)  (but: she is in Holiday until end of July)  first-come-first-served appointments Have a nice summer!