物件導向軟體之架構(Object-Oriented Software Construction)探討

The organization of behavior: A neuropsychological theory

In this chapter we survey the theory of two-party communication complexity. This field of theoretical computer science aims at studying the following, seemingly very simple, scenario: There are two players Alice who holds an n-bit string x and Bob who holds an n-bit string y. Their goal is to communicate in order to compute the value of some boolean function f(x, y), while exchanging a number of bits which is as small as possible. In the first part of this survey we present, mainly by giving examples, some of the results (and techniques) developed as part of this theory. We put an emphasis on proving lower bounds on the amount of communication that must be exchanged in the above scenario for certain functions f . In the second part of this survey we will exemplify the wide applicability of the results proved in the first part to other areas of computer science. While it is obvious that there are many applications of the results to problems in which communication is involved (e.g., in distributed systems), we concentrate on applications in which communication does not appear explicitly in the statement of the problems. In particular, we present results regarding the following models of computation: • Finite automata • Turing machines • Decision trees • Ordered binary decision diagrams (OBDDs) • VLSI chips • Networks of threshold gates We provide references to many other issues and applications of communication complexity which are not discussed in this survey.

Communication Complexity

Many systems migrate toward increasing or decreasing modularity, yet no explicit causal models exist to explain this process. In this article the author builds a general theory of modular systems, drawing on systems research from many disciplines, and then uses this general theory to derive a model of interfirm product modularity, including testable research propositions. The product model provides a valuable tool for predicting technological trajectories, and it demonstrates how the general theory can be applied to specific systems.

Toward a General Modular Systems Theory and Its Application to Interfirm Product Modularity

In semistructured databases there is no schema fixed in advance. To provide the benefits of a schema in such environments, we introduce DataGuides: concise and accurate structural summaries of semistructured databases. DataGuides serve as dynamic schemas, generated from the database; they are useful for browsing database structure, formulating queries, storing information such as statistics and sample values, and enabling query optimization. This paper presents the theoretical foundations of DataGuides along with an algorithm for their creation and an overview of incremental maintenance. We provide performance results based on our implementation of DataGuides in the Lore DBMS for semistructured data. We also describe the use of DataGuides in Lore, both in the user interface to enable structure browsing and query formulation, and as a means of guiding the query processor and optimizing query execution.

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DataGuides: Enabling Query Formulation and Optimization in Semistructured Databases

Great Aunt Eugenia and other automata Sundry machines Implementing finite automata Implementation and realization Behavioural equivalence, SP partitions and reduced machines Parallel and serial composition of automata The parallel decomposition theorem The serial decomposition theorem The lattice of SP partitions Analysis of machines Concurrent systems: net theory Concurrent systems: the calculus of communicating systems. Appendix: Sets, relations and functions.

An Introduction to Automata Theory

The next model we examine is pleasantly simple and quite closely related to Nets on the condition/event level.

Loosely Coupled Systems

The object of this paper is to present some results in the formal study of path expressions. Path expressions, or GR-paths, are syntactic objects, that is, terminals strings of a grammar. GR-paths themselves may also be regarded as grammars; each GR-path determines a trace language, in the sense of [Maz 77]. In this sense, GR-paths may be thought of as a defining systems, in that each is associated with a set of possible histories of concurrent behaviour, represented formally by traces. In this exposition, traces are represented as n-tuples of strings and it is briefly shown how such n-tuples determine labelled, partially ordered sets, a popular way of modelling concurrent histories.

Michael W. Shields

Papers

An Introduction to Automata Theory

Loosely Coupled Systems

Adequate Path Expressions

A theoretical framework for multiple neural network systems

Semantics of Parallelism