[Pl-seminar] Semantics Seminar Schedule

[Mitchell Wand]

NU Programming Languages Seminar
Wednesday, October 22, 2003
206 Egan  Hall, Northeastern University
    (building 60 on http://www.campusmap.neu.edu/)  
1145-145. Bring your lunch.

Paul C. Attie
Northeastern University

A Compositional Automaton-based Model for Dynamic Systems

We present a compositional model of dynamic systems, based on I/O
automata.  In our model, automata can be created and destroyed
dynamically, as computation proceeds.  In addition, an automaton can
dynamically change its signature, that is, the set of actions in which
it can participate.  This allows us to model mobility, by
enforcing the constraint that only automata at the same location may
synchronize on common actions.

Our model is hierarchical: a dynamically changing system of interacting
automata is itself modeled as a single automaton that is "one level
higher." This can be repeated, so that an automaton that represents
such a dynamic system can itself be created and destroyed. This allows
us to model the addition and removal of entire subsystems with a single
action.

We show that trace inclusion is monotonic with respect to parallel
composition in a dynamic system only under certain
conditions. Specifically, if automaton creation is not correlated with
external behavior, then trace inclusion is not monotonic with respect
to parallel composition.

Our trace inclusion results enable a refinement methodology for
dynamic systems that is independent of specific methods of
establishing trace inclusion. This provides much more flexibility in
refinement than a methodology which is, for example, based on the
monotonicity of forward simulation with respect to parallel
composition. In the latter every automaton must be refined using
forward simulation, whereas in our framework different automata in the
system can be refined using different methods.

Upcoming Events:

10/29: Jeff Palm: AspectJ

11/5: Richard Cobbe: Environmental Acquisition

11/12: Theo Skotoniotis

11/19: Dale Vaillancourt: Separation Logic

12/2: Greg Pettyjohn: Cocoon

12/9: Phillipe Meunier

--Mitch