Sequential Relational Decomposition

The concept of decomposition in computer science and engineering is considered a fundamental component of computational thinking and is prevalent in design of algorithms, software construction, hardware design, and more. We propose a simple and natural formalization of sequential decomposition, in which a task is decomposed into two sequential sub-tasks, with the first sub-task to be executed before the second sub-task is executed. These tasks are specified by means of input/output relations. We define and study decomposition problems, which is to decide whether a given specification can be sequentially decomposed. Our main result is that decomposition itself is a difficult computational problem. More specifically, we study decomposition problems in three settings: where the input task is specified explicitly, by means of Boolean circuits, and by means of automatic relations. We show that in the first setting decomposition is NP-complete, in the second setting it is NEXPTIME-complete, and in the third setting there is evidence to suggest that it is undecidable. Our results indicate that the intuitive idea of decomposition as a system-design approach requires further investigation. In particular, we show that adding a human to the loop by asking for a decomposition hint lowers the complexity of decomposition problems considerably

Sequential Relational Decomposition

The concept of decomposition in computer science and engineering is considered a fundamental component of computational thinking and is prevalent in design of algorithms, software construction, hardware design, and more. We propose a simple and natural formalization of sequential decomposition, in which a task is decomposed into two sequential sub-tasks, with the first sub-task to be executed before the second sub-task is executed. These tasks are specified by means of input/output relations. We define and study decomposition problems, which is to decide whether a given specification can be sequentially decomposed. Our main result is that decomposition itself is a difficult computational problem. More specifically, we study decomposition problems in three settings: where the input task is specified explicitly, by means of Boolean circuits, and by means of automatic relations. We show that in the first setting decomposition is NP-complete, in the second setting it is NEXPTIME-complete, and in the third setting there is evidence to suggest that it is undecidable. Our results indicate that the intuitive idea of decomposition as a system-design approach requires further investigation. In particular, we show that adding a human to the loop by asking for a decomposition hint lowers the complexity of decomposition problems considerably

Object-oriented views: a novel approach for tool integration in design environments (dissertation)

Object-oriented databases have been proposed to serve as the data management component of integrated design environments. One central database represents a bottleneck, however, requiring all design tools to work on the same information model and preventing the extensibility of the system over time. In this dissertation, I propose a view-based object server that successfully addresses these problems by supporting design views tailored to the needs of individual design tools.A view on an object-oriented schema corresponds to a virtual subschema graph with restructured generalization and property decomposition hierarchies. I present a methodology for supporting multiple view schemata, called MutliView. MultiView is anchored on the following four ideas: (1) the customization of individual classes using object algebra, (2) the integration of these derived classes into one global schema graoh, (3) the extraction of virtual and base classes from the global schema as required by the view, and (4) the generation of a class hierarchy for these selected view classes. MutliView's division of view specification into these well-defined tasks, some of which have been successfully automated, makes it a powerful tool for supporting the specification of views by non-database experts while enforcing view consistency.In this dissertation, I describe solutions for all four tasks underlying MultiView. For the first task, I have formulated class derivatin operators modeled after the well-known relational algebra operators. For the second task, I have developed a classification algorithm that automatically integrates derived classes into one global schema. For the third task, I have designed a view definition language that can be used to declaratively specify the view classes required for a particular view. For the last task, I have developed an algorithm that generates a complete, minimal and consistent view schema. I present proofs of correctness, complexity analysis, and numerous illustrative examples for all algorithms.MultiView is applied to address the tool integration problem in a behavioral synthesis system. For this purpose, I first develop a unified design object model for behavioral synthesis. I then formulate customized design views of this model tailored to the needs of particular design tools. The resulting system allows the design tools to work on their view of the information model, while MultiView assures the consistent integration of the diverse design data into one object model

Plan-based delivery composition in intelligent tutoring systems for introductory computer programming

In a shell system for the generation of intelligent tutoring systems, the instructional model that one applies should be variable independent of the content of instruction. In this article, a taxonomy of content elements is presented in order to define a relatively content-independent instructional planner for introductory programming ITS's; the taxonomy is based on the concepts of programming goals and programming plans. Deliveries may be composed by the instantiation of delivery templates with the content elements. Examples from two different instructional models illustrate the flexibility of this approach. All content in the examples is taken from a course in COMAL-80 turtle graphics

Computational tasks in robotics and factory automation

The design of Manufacturing Planning and Control Systems (MPCSs) — systems that negotiate with Customers and Suppliers to exchange products in return for money in order to generate profit, is discussed.\ud \ud The computational task of MPCS components are systematically specified as a starting point for the development of computational engines, as computer systems and programs, that execute the specified computation. Key issues are the overwhelming complexity and frequently changing application of MPCSs

A survey of agent-oriented methodologies

This article introduces the current agent-oriented methodologies. It discusses what approaches have been followed (mainly extending existing object oriented and knowledge engineering methodologies), the suitability of these approaches for agent modelling, and some conclusions drawn from the survey