PHI - A Logic-Based Tool for Intelligent Help Systems

We introduce a logic-based system which improves the performance of intelligent help systems by supplying them with plan generation and plan recognition components. Both components work in close mutual cooperation There are two modes of cross-talk between them, one where plan recognition is done on the basis of abstract plans provided by the planner and the other where optimal plans are generated based on recognition results The exam pies which are presented are taken from an operating system domain, namely from the UNIX mail domain 1 Introduction Intelligent help systems aim at providing advanced active help to the users of complex software systems (cf. The performance of these help systems can In-considerably improved if they are supplied with plan recognition and plan generation capabilities Observing a user and recognizing his goals enables the system to help by taking into account the current state of the system as well as the users level of education and current behavior Moreover, if a planning capability is available user-specific support can be given by proposing appropriate plans which exactly is what the PHI system aims to achieve 1 PHI (cf. the figure below) is a tool for intelligent help systems. It provides both a plan recognizer and a planning component and one of its main characteristics consists in the close mutual cooperation between the two components There are several cross-talk modes. The first one is devoted to realizing plan recognition on the basis of abstract plans produced by the planner Abstract plans are those which represent a variety of 'concrete" observable action sequences by admitting several degrees of freedom like variables (abstracting from the objects m volved), abstract commands (abstracting from the names *This work w;ts supported by the German Ministry for Research and Technology (BMFT) under contract ITW 9000 8 as part of the PHI project. of actions which have the same effects), or temporal abstraction (abstracting from the point in time at which an action occurs). The generation of plans is based on standard assumptions concerning goals that typically occur or are specific to a certain user. Abstract plans are generated from these formal plan specifications In doing so, the planner not only performs planning from first principles but is able to recuse already existing plans which are stored in a library (planning from second principles). The plans provided serve as plan hypotheses in the recognition process. Taking abstract plans instead of …