27763023
Computability of Minimizers and Separating Hyperplanes
We prove in recursive analysis an existence theorem for computable minimizers of convex computable continuous real-valued functions, and a computable separation theorem for convex sets in ℝm. 
 
 
 
Mathematics Subject Classification: 03F60, 52A40.
16497195
Computable Economic Analysis
This paper discusses an economic equilibrium theory with computabil-ity constraints on both the magnitudes (prices, quantities, etc.) and the operations (to perceive, evaluate, choose, communicate, etc) that agents can use. Prices and quantities are computable numbers (Turing (1936)), and preference relations, utility functions, demand functions are computable (in the sense of Moschovakis (1964)). We present sharper versions of several traditional assertions on utility representation , existence of consumer demand functions, the fundamental welfare theorems, characterizations of market excess demands. We also give a \computable coun-terexample" to the existence of a competitive equilibrium. These results can be interpreted as possibility and impossibility results in computability-bounded ratio-nality, and in computational economics.
30089105
A fixed point theorem for o-minimal structures
We prove a definable analogue to Brouwer's Fixed Point Theorem for o-minimal structures of real closed field expansions: A continuous definable function mapping from the unit simplex into itself admits a fixed point, even though the underlying space is not necessarily topologically complete. Our proof is direct and elementary; it uses a triangulation technique for o-minimal functions, with an application of Sperner's Lemma. (© 2003 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
991816
Wrapping coarse-grained objects using standard infrastructure technology
There are two basic approaches to migrating a particular subsystem: reengineering and wrapping. The author considers coarse-grained object wrapping. In wrapping, the original subsystem is essentially integrated into the new setting using infrastructure technologies. Legacy systems that have evolved over many years are notoriously difficult to decompose. Wrapping is most effective if the legacy system can be decomposed into a few large chunks where the number of communication paths among subsystems is minimized. The author discusses the use of infrastructure technology such as CORBA (Common Object Request Broker Architecture)
8364384
Understanding Software Systems Using Reverse Engineering Technology
Software engineering research has focused primarily on software construction, neglecting software maintenance and evolution. Observed is a shift in research from synthesis to analysis. The process of reverse engineering is introduced as an aid in program understanding. This process is concerned with the analysis of existing software systems to make them more understandable for maintenance, re-engineering, and evolution purposes. Presented is reverse engineering technology developed as part of the Rigi project. The Rigi approach involves the identi cation of software artifacts in the subject system and the aggregation of these artifacts to form more abstract system representations. Early industrial experience has shown that software engineers using Rigi can quickly build mental models from the discovered abstractions that are compatible with the mental models formed by the maintainers of the underlying software.
12666551
Fused data-centric visualizations for software evolution environments
During software evolution, several different facets of the system need to be related to one another at multiple levels of abstraction. Current software evolution tools have limited capabilities for effectively visualizing and evolving multiple system facets in an integrated manner. Many tools provide methods for tracking and relating different levels of abstraction within a single facet. However, it is less well understood how to represent and understand relationships between and among different abstraction hierarchies, i.e. for inter-hierarchy relations. Often, these are represented and explored independently, making them difficult to relate to one another. As a result, engineers are likely to have difficulty understanding how the various facets of a system relate and interact. We describe preliminary results of a collaborative research project between industry and academia to enhance the inter-hierarchy visualization capabilities of an existing software evolution environment called "KLOCwork Suite". Specifically, we describe our efforts to add a "fused" visualization based on story board diagrams. This visualization integrates - or "fuses" - facets of architecture, behavior and data. We describe how these diagrams bridge currently isolated visualizations of system information, and argue how they can help drive architecture excavation tasks.
12936831
On designing an experiment to evaluate a reverse engineering tool
The Rigi reverse engineering system is designed to analyze and summarize the structure of large software systems. Two contrasting approaches are available for visualizing software structures in the Rigi graph editor. The first approach displays the structures through multiple, individual windows. The second approach, simple hierarchical multi-perspective (SHriMP) views, employs fisheye views of nested graphs. The paper describes the design of an experiment to evaluate these alternative user interfaces. Various results from a preliminary pilot study to test the experiment design are reported.
7493579
CLARE—a Prolog database machine
The CLAuse Retrieval Engine (CLARE) is a coprocessor system which based on two-stage filtering, for handling large sets of disc resident clauses in Prolog database applications. The overall architecture and the timing measurements of the first stage CLARE hardware are reported. The timing measurements shows that the first stage CLARE hardware can perform search operations on data transferring at a rate up to 4.5 million double bytes per second.