We describe an approach to intelligent user interfaces, based on the idea of making the computer a collaborator, and an application-independent technology for implementing such interfaces.

The planning competition has become a regular part of the biennial Artificial Intelligence Planning and Scheduling (AIPS) conferences. The 2000 competition featured a much larger group of participants and a wide variety of different approaches to planning. Besides the dramatic increase in participation, the 2000 competition demonstrated that planning technology has taken a giant leap forward in performance since 1998. The 2000 competition featured planning systems that were orders of magnitude faster than the planners of just two years prior.

Tokenplan is a planner based on the use of Petri nets. Its main feature is the flexibility it offers in the way it builds the planning graph. The next step is to demonstrate the benefits we expect from our planner in planning problems involving optimization and uncertainty handling.

System R is a variant of the original planning algorithm used in strips. It was the only planner that competed in both the automatic and hand-tailored tracks in the Fifth International Conference on Artificial Intelligence Planning and Scheduling competition.

AltAlt is designed to exploit the complementary strengths of two of the currently popular competing approaches for plan generation: (1) graphplan and (2) heuristic state search. It uses the planning graph to derive effective heuristics that are then used to guide heuristic state search. The heuristics derived from the planning graph do a better job of taking the subgoal interactions into account and, as such, are significantly more effective than existing heuristics. AltAlt was implemented on top of two state-of-the-art planning systems: (1) stan3.0, a graphplan-style planner, and (2) hsp-r, a heuristic search planner.

Shop is a hierarchical task network planning algorithm that is provably sound and complete across a large class of planning domains. It plans for tasks in the same order that they will later be executed, and thus, it knows the current world state at each step of the planning process. For example, shop's preconditions can include logical inferences, complex numeric computations, and calls to external programs.

Fast-forward (FF) was the most successful automatic planner in the Fifth International Conference on Artificial Intelligence Planning and Scheduling (AIPS '00) planning systems competition. Like the well-known hsp system, FF relies on forward search in the state space, guided by a heuristic that estimates goal distances by ignoring delete lists. It differs from HSP in a number of important details. This article describes the algorithmic techniques used in FF in comparison to hsp and evaluates their benefits in terms of run-time and solution-length behavior.

Mips is a planning system that applies binary decision diagrams (BDDs) to compactly represent world states in a planning problem and efficiently explore the underlying state space. It was the first general planning system based on model-checking methods. At the Fifth International Conference on Artificial Intelligence Planning and Scheduling (AIPS'00), mips was one of five planning systems to be awarded for distinguished performance in the fully automated track. This article gives a brief introduction to, and explains the basic planning algorithm used by, mips, using a simple logistics problem as an example.

We briefly describe the implementation and evaluation of a novel plan synthesis system, called AltAlt. AltAlt is designed to exploit the complementary strengths of two of the currently popular competing approaches for plan generation: (1) graphplan and (2) heuristic state search. It uses the planning graph to derive effective heuristics that are then used to guide heuristic state search. The heuristics derived from the planning graph do a better job of taking the subgoal interactions into account and, as such, are significantly more effective than existing heuristics. AltAlt was implemented on top of two state-of-the-art planning systems: (1) stan3.0, a graphplan-style planner, and (2) hsp-r, a heuristic search planner.

We briefly describe the implementation and evaluation of a novel plan synthesis system, called AltAlt. AltAlt is designed to exploit the complementary strengths of two of the currently popular competing approaches for plan generation: (1) graphplan and (2) heuristic state search. It uses the planning graph to derive effective heuristics that are then used to guide heuristic state search. The heuristics derived from the planning graph do a better job of taking the subgoal interactions into account and, as such, are significantly more effective than existing heuristics. AltAlt was implemented on top of two state-of-the-art planning systems: (1) stan3.0, a graphplan-style planner, and (2) hsp-r, a heuristic search planner.