META-EVALUATI ON OF ACTORS WITH SIDE-EFFECTS by

feta-evaluetton is a process which symbolically evaluates an actor and checks to see whether the actor fulfills its contract (specification). A formalism for writing contracts for actors with side-effects which allow sharing of data is presented. Typical examples of actors with side-effects are the cell, actor counterparts of the LISP function rplace and rplacd, and procedures whose computation depends upon their input htstory. Meta-evaluation of actors with side-effets is carried out by using sttuattonta toags which denotes a situation (local state of an actor systems at the moment of the transmissions of messages). It is illustrated how the situational tags are used for proving the termination of the activation of actors. This report describes research done at the Artificial Intelligence laboratory of the massachusetts Institute of Technology. Support for the laboratory's artificial intelligence reseach is provided in part by the Advance Research Projects Agency of the Department of Defence under Office of Naval Research contract N00014-74-C-0643. Working paper are informal papers intended for internal use.