Motivating example  You want to do a cruise on the Nile  Your electronic secretary has to book  A return flight to Egypt  And a cruise such that the cruise happens between the back and forth legs of your flight While minimizing waiting time in between.

Example (continued) Your electronic secretary deals with two travel agents:  Agent A, who is quick, and can do flights and cruises, but only one at a time  And Agent B, who is slow and only does cruises. Solution :  Let agent A book the flight while agent B books the cruise.  In case A finishes before B even starts, let A book the cruise as well.

Booking a flight and a cruise in parallel Original specification Alternative specification

Conclusion  Commonly used criteria for equivalence of specifications are inadequate when the specifications are used in certain contexts  For compositional verification we use carefully crafted notions of equivalence and implementation.

General research goals  Pinpoint subtle features of concurrent systems that are inadequately modeled by contemporary techniques, leading to untrustworthy specifications.  Provide reliable specification techniques through mathematical rigor.  Ultimately leading to trustworthy software.