Abstract: A schedule for a complex activity is obtained by a scheduling system using a method of constraint-based iterative repair. A predetermined initial schedule is iteratively repaired, repairs being made during each iteration only to portions of the schedule that produce a constraint violation, until an acceptable schedule is obtained. Since repairs are made to the schedule only to repair violated constraints, rather than to the entire schedule, schedule perturbations are minimized, thereby reducing problems with the dynamic performance of the scheduling system and minimizing disruption to the smooth operation of the activity. All constraints on the scheduling activity can be evaluated simultaneously to produce a solution that is near optimal with respect to all constraints.

Abstract: The invention facilitates modeling of an enterprise. A model developer uses a high-level modeling language to describe the enterprise with constructs that are more readily accessible to the model developer than those used in other previous modeling languages. The high-level description is translated into a low-level description that can more readily be used by a processing device to dynamically exercise the model. The constructs of the modeling language shield the model developer from many of the mundane tasks associated with maintaining data integrity in complex data structures. Of particular importance, the modeling language includes data constructs that make it easy to track and maintain data that changes during execution of a program, without considerable effort on the part of the model developer. These data constructs can be used to restore various states of the modeled enterprise during execution of the program, either automatically or at the direction of a user.

Abstract: The invention enables multiple users to simultaneously access and change the contents of a database in a flexible manner. Each user interacts with a working copy of a master copy of the database. The contents of each of the working copies of the database can be accessed and manipulated so that the contents of the working copy of the database can be revised. Each user has control over whether to the "publish" revisions made to the contents of that user's working copy of the database, i.e., write the revisions to the master copy and present other users with the option of including the revisions in the working copies of those other users. Each user has the option to reject revisions published by other users so that the contents of each user's working copy of the database may or may not be maintained consistent with other working copies of the database operated on by other users.