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This paper describes techniques developed for conflict detection during plan integration. Agents' intensions are represented with intended goal structure (IGS) and the E-PERT diagrams. Conflicts are classified as goal, plan, and belief conflicts. Before integrating individual plans and detecting plan conflicts, agents first detect and eliminate their goal conflicts by exchanging their IGS. Plan integration is done through merging individual E-PERT diagrams. Project estimation and review technique (PERT) diagrams have been used extensively in the systems analysis area since the 1980s to provide a global consistent view of parallel activities within a project. We extended the PERT diagrams for use in the plan integration activity within multi-agent systems (MAS). The E-PERT diagram contributes to maintain traceable temporal relations among agents' local scheduled actions. Combined with pattern matching, plan conflicts due to resource sharing, or conflicting conditions (i.e., postconditions of one action disabling preconditions of another action) can be detected. The conflict detection techniques are implemented in a sensible agent testbed to promote deployment and performance analysis.

This paper' models. analyzes, accommodates and simulates potential failures which may occur in a materials handling system with fitended Petri nets (EPNs). Detailed EPN based subnets are provided to study and accommodate occurred failures. The subnet structural properties and the overall system properties are preserved The Stochastic Petri Net Package (SPNP) is used for simulation studies.

In this paper, hierarchical time-extended Petri nets (H-EPNs), an extended Petri net based modeling and analysis tool, are used to derive the coordination level model of hierarchically decomposable systems, viewed from a three-level hierarchical structure of organization, coordination and execution of tasks. A two-layer (vertical) coordination level framework, consisting of the dispatcher/analyzer and the H-EPN controller is presented. A detailed two sub-level (horizontal) H-EPN controller model is derived to model system operations (including system soft failures). Error classification based on the interaction between the various system coordinators is derived from the H-EPN model. The H-EPN approach preserves multi-resolutional system details as well as effective communication flows between the various subsystems. A simple example illustrates the proposed approach. The important H-EPN properties of boundedness, safeness and reversibility are verified.