Hiroaki Etoh

Finding a Connection Chain for Tracing Intruders

Intruders usually log in through a chain of multiple computer systems to hide their origins before breaking into their targets, which makes tracing difficult. In this paper we present a method to find the connection chain of an intruder for tracing back to the origin. We focus on telnet and rlogin as interactive applications intruders use to log in through hosts.

Curvilinear detailed routing algorithm and its extension to wire-spreading and wire-fattening

This article describes an algorithm for curvilinear detailed routing. We significantly improved the average time performance of Gaos algorithm by resolving its bottleneck related to generation of fan-shaped forbidden regions along a wire. We also describe a method for simultaneous wire-spreading and wire-fattening, which consists of enlarging forbidden regions generated by the detailed routing algorithm as long as there remains any space through which wires can pass. From the experiments we obtained the result that the average CPU time of the detailed routing algorithm is almost linear to the length of a wire. Since the curvilinear detailed routing is efficient in terms of space usage, the proposed algorithm is important especially for densely wired printed circuit boards such as PGA packages, BGA packages, and MCMs. We can also expect improvements on the electrical characteristics and the production yield by applying wire-spreading and wire-fattening to them.

Network-based problem detection for distributed systems

We introduce a network-based problem detection framework for distributed systems, which includes a data-mining method for discovering dynamic dependencies among distributed services from transaction data collected from network, and a novel problem detection method based on the discovered dependencies. From observed containments of transaction execution time periods, we estimate the probabilities of accidental and non-accidental containments, and build a competitive model for discovering direct dependencies by using a model estimation method based on the online EM algorithm. Utilizing the discovered dependency information, we also propose a hierarchical problem detection framework, where microscopic dependency information is incorporated with a macroscopic anomaly metric that monitors the behavior of the system as a whole. This feature is made possible by employing a network-based design which provides overall information of the system without any impact on the performance.

Curvilinear detailed routing with simultaneous wire-spreading and wire-fattening

This paper describes an algorithm for curvilinear detailed routing. We significantly improved the average time performance of Gaos algorithm by resolving its bottleneck related to generation of fan-shaped forbidden regions along a wire. We also describe a method for simultaneous wire-spreading and wire-fattening, which consists of enlarging forbidden regions generated by the detailed routing algorithm as long as there remains any space through which wires can pass. From the experiments we obtained the result that the average CPU time of the detailed routing algorithm is almost linear to the length of a wire. Since the curvilinear detailed routing is efficient in terms of space usage, the proposed algorithm is important especially for densely wired printed circuit boards such as pin grid array packages, ball grid array packages, and multichip modules. We can also expect improvements on the electrical characteristics and the production yield by applying wire-spreading and wire-fattening to them.

Topological routing path search algorithm with incremental routability test

The article describes a topological routing path search algorithm embedded in the auto-router for printed circuit boards. The algorithm searches for a topological path that is guaranteed to be transformable into a physical wire satisfying design rules. The authors propose a method for incrementally verifying design rules during topological path search in a graph based on constrained Delaunay triangulation, and describe several improvements to the routing path search algorithm that remedy the overhead of the routability test and avoid combinatorial explosion.

Zephyr: toward true compiler-based programming in Prolog

Prolog is widely used in prototyping, especially in artificial intelligence, but it has yet to gain widespread acceptance in application development. We think that the problems in this area result from the programming style enforced in existing Prolog systems. Zephyr is a new Prolog system refined and enhanced to help solve such problems. It allows users to do modular programming by always using a compiler instead of an interpreter. In this paper, we describe the unique features of Zephyr which make this possible, focusing especially on package, metafunctions, and tables, and the implementation of the system on OS/2®.

Introduction of a Pachage System into Prolog

In this paper we introduce a package system enabling Prolog to support modularity and separate compilation. A package system is for the development of large systems and is an important feature when coding is done by a number of programmers.