This paper postulates a rigorous method for the construction of classical planning domain models. We describe, with the help of a non-trivial example, a tool supported method for encoding such models. The method results in an `object-centred' specification of the domain that lifts the representation from the level of the literal to the level of the object. Thus, for example, operators are defined in terms of how they change the state of objects, and planning states are defined as amalgams of the objects' states. The method features two classes of tools: for initial capture and validation of the domain model; and for operationalising the domain model (a process we call compilation) for later planning. Here we focus on compilation tools used to generate macros and goal orders to be utilised at plan generation time. We describe them in depth, and evaluate empirically their combined benefits in plan-generation speed-up. The method's main benefit is in helping the modeller to pro...

: A core concept in discussions about technological support for knowledge management is the Corporate Memory. A Corporate or Organizational Memory can be characterized as a comprehensive computer system which captures a company's accumulated know-how and other knowledge assets and makes them available to enhance the efficiency and effectiveness of knowledge-intensive work processes. The successful development of such a system requires a careful analysis of established work practices and available information-technology (IT) infrastructure. This is essential for providing a cost-effective solution which will be accepted by the users and can be evolved in the future. The current paper compares and summarizes our experiences from three case studies on Corporate Memories for supporting various aspects in the product life-cycles of three European corporations. Based on the conducted analyses and prototypical implementations, we sketch a general framework for the development methodology, arc...

Compared with frame-based systems, description logics have the advantage of well-defined semantics and powerful inferences. In order to exploit these advantages in technical domains, the ability to use concrete domains is needed, e.g. systems of (in)equalities over (non)linear polynomials to handle physical laws. Existing systems can only cope with comparisons between attributes. We present an approach that considerably improves the expressiveness of the concrete domains. CTL is based on the ideas presented in [1] and [5]. Concrete domains are realised through a well-deøned interface to external algorithms. Constraint Logic Programming (CLP) systems allow us to easily realise a whole range of concrete domains, e.g. over sets of symbols and numbers. In particular, we are able to handle systems of arbitrary linear polynomials. They also enable us to automatically participate in recent and future improvements in the areas of CLP and computer algebra, e.g. systems capable of handling ar...

. Since we consider theory refinement (TR) as a possible key concept for a methodologically clear view of knowledge-base maintenance, we try to give a structured overview about the actual state-of-the-art in TR. This overview is arranged along the description of TR as a search problem. We explain the basic approach, show the variety of existing systems and try to give some hints about the direction future research should go. 1 Introduction Based upon experiences from previous projects and application studies concerning logic-based knowledge representation [6, 2, 13] and knowledge evolution [15, 11], the aim of the VEGA project (Knowledge Validation and Exploration by Global Analysis) is to contribute to a methodology of maintaining declarative knowledge [1, 12, 14]. This goal demands techniques and methods for all maintenance activities (e.g. debugging, adaptation, change) within the life-cycle of knowledge bases (KBs)---relying on elementary building blocks (exploration and validatio...

A knowledge-based process-planning system for generating workplans for idealized lathe CNC machines is discussed. It transforms CAD-like diagrams of rotationalsymmetric workpieces into abstract NC programs. To simplify development and evolution, declarative representations are used for all processing stages and steps, including a qualitative simulation of lathe turning. The version presented here, 'CAD2NC, was written entirely in RELFUN, a functional-logic language integration. Actually, 'CAD2NC is a mostly functional program consisting of three principal transformation components. First, a flat term representation of the CAD-like geometrical raw data is parsed into a recursively classified workpiece representation, exhibiting productionrelevant workpiece features (e.g. `shoulders' and `grooves') through nested subterms. From this, a skeletal production plan is created by mapping features to sequential, commutative, and alternative subplans (ultimately, lathe actions). Final...