Planning Cases by Change of Representation Language Ralph Bergmann bergmann@informatik.uni-kl.de Wolfgang Wilke wilke@informatik.uni-kl.de Centre for Learning Systems and Applications (LSA) University of Kaiserslautern, P.O.-Box 3049, D-67653 Kaiserslautern, Germany Abstract Abstraction is one of the most promising approaches to improve the performance of problem solvers. In several domains abstraction by dropping sentences of a domain description -- as used in most hierarchical planners -- has proven useful. In this paper we present examples which illustrate significant drawbacks of abstraction by dropping sentences. To overcome these drawbacks, we propose a more general view of abstraction involving the change of representation language. We have developed a new abstraction methodology and a related sound and complete learning algorithm that allows the complete change of representation language of planning cases from concrete to abstract. However, to achieve a powerful change of th...

Resource reasoning has been at the heart of many of the successful ai based scheduling systems -- yet no attempt has been made to integrate the best techniques from scheduling with the best techniques from ai activity based planning. This paper presents a set of incremental algorithms which create two separate profiles to represent the optimistic and pessimistic use of resources within an activity plan. These allow the planner to ensure that there is a feasible assignment of resources available within any plan state being considered. The paper demonstrates how these profiles can be used to track the usage of a variety of different resource types and how they can be used to provide detailed and relevant information when a resource constraint conflict is detected. 1 Introduction Resource reasoning has been at the heart of many of the successful ai based scheduling systems -- yet no attempt has been made to integrate the best techniques from scheduling with the best techniques from ai ...

Condition satisfaction in planning has received a great deal of experimental and formal attention. A "Truth Criterion" lies at the heart of many planners and is critical to their capabilities and performance. However, there has been little study of ways in which the search space of a planner incorporating such a Truth Criterion can be guided. The aim of this document is to give a description of the use of condition "type" information to inform the search of an AI planner and to guide the production of answers by a planner's truth criterion algorithm. The authors aim to promote discussion on the merits or otherwise of using such domain-dependent condition type restrictions as a means to communicate valuable information from the domain writer to a general purpose domain-independent planner 1 . Introduction to Condition Typing Research in AI planning has introduced a range of progressively more powerful techniques to address increasingly more realistic applications (Allen, Hendler & Ta...

I wish to thank Bonnie Webber. Without her patience and her seemingly endless depths of insight, I might never have completed this thesis. I am enormously grateful for her guidance. I also owe many thanks to Ellen Prince. She is an intellectual leader at Penn who has helped many, including me, find a way through the jungle of discourse analysis. I am indebted to every professor who has taught me. Special thanks to Robin Clark for being a member of my dissertation committee. I am very lucky to have worked with Aravind Joshi. He is a continual source of knowledge in the DLTAG meetings. The field of computational linguistics has already benefited from his sentencelevel work; I fully expect he and Bonnie will produce similarly useful results with DLTAG. Also in DLTAG, Eleni Miltsakaki and Rashmi Prasad, and later Cassandre Creswell and Jason Teeple all provided stimulation and solace. Their great company and great effort on DLTAG projects taught me to appreciate how much can be done when minds work together. I look forward to the chance to work with them in the future. I am also thankful to Martha Palmer, Paul Kingsbury, and Scott Cotton for allowing me to work with them on the Propbank project and supplement both my income and my work in discourse. On a personal note, the Forbes, Finley, and Riley families deserve thanks for giving me love and diversion and balance and talking me through my education. Most of all, thanks to Enrico Riley, for being everything to me.

As realistic systems are built and commercial toolkits are created for planning and scheduling applications, it becomes increasingly important that modularisation of these "standard" components is attempted. This can lead to re-usability, embeddability and improved implementation provision. One early example of a standardised component is the Truth Criterion condition establishment algorithm which is now found at the heart of most activity based planning systems. The modularisation of this algorithm has led to an explosion of further development, empirical and theoretical study of this component. The provision of powerful constraint management languages and tools could lead to a rapid expansion of the benefits to be gained by identifying more standard components that can be combined and re-used in planning and scheduling systems. O-Plan2 is a command, planning and control architecture which has an open modular structure intended to allow experimentation on or replacement of various components. This paper describes the modular structure of the system along with the internal and external interface languages and protocols which are being developed on the O-Plan2 project. The research is seeking to isolate functionality that may be generally required in a number of applications and across a number of different planning, scheduling and control systems. This paper is intended to further discussions on the identification of suitable "standard" re-usable components in planning and scheduling systems.

Interaction with an adaptive hypertext can be seen as a form of "goal-oriented" dialogue, where the user asks for information through a set of predefined queries and the system answers ensuring that the global communicative goal of the information process is achieved through a sequence of dialogue sections (hypermedia nodes). The system establishes what to say to the user at every turn of the dialogue based on the user model settings and on the interaction history. Planning on demand the information content of a hypertext node that responds to a particular link selection in a particular context requires a 'reactive' approach; this differs from common hypertext planning in that it applies local adjustment criteria to an overall plan and, in mixed-initiative situations, tries to fit together the system's and the user's points of view. Keywords Dynamic hypertext generation, mixed-initiative interaction, automated presentation of information. INTRODUCTION Plan-based approaches to deep ...