Reason Maintenance - State of the Art

This paper describes state of the art in reason maintenance with a focus on its future usage in the KiWi project. To give a bigger picture of the field, it also mentions closely related issues such as non-monotonic logic and paraconsistency. The paper is organized as follows: first, two motivating scenarios referring to semantic wikis are presented which are then used to introduce the different reason maintenance techniques

Explanation-based learning for diagnosis

Diagnostic expert systems constructed using traditional knowledge-engineering techniques identify malfunctioning components using rules that associate symptoms with diagnoses. Model-based diagnosis (MBD) systems use models of devices to find faults given observations of abnormal behavior. These approaches to diagnosis are complementary. We consider hybrid diagnosis systems that include both associational and model-based diagnostic components. We present results on explanation-based learning (EBL) methods aimed at improving the performance of hybrid diagnostic problem solvers. We describe two architectures called EBL_IA and EBL(p). EBL_IA is a form fo "learning in advance" that pre-compiles models into associations. At run-time the diagnostic system is purely associational. In EBL(p), the run-time diagnosis system contains associational, MBD, and EBL components. Learned associational rules are preferred but when they are incomplete they may produce too many incorrect diagnoses. When errors cause performance to dip below a give threshold p, EBL(p) activates MBD and explanation-based "learning while doing". We present results of empirical studies comparing MBD without learning versus EBL_IA and EBL(p). The main conclusions are as follows. EBL_IA is superior when it is feasible but it is not feasible for large devices. EBL(p) can speed-up MBD and scale-up to larger devices in situations where perfect accuracy is not required

Focusing ATMS Problem-Solving: A Formal Approach

The Assumption-based Truth Maintenance System (ATMS) is a general and powerful problem-solving tool in AI. Unfortunately, its generality usually entails a high computational cost. In this paper, we study how a general notion of cost function can be incorporated into the design of an algorithm for focusing the ATMS, called BF-ATMS. The BF-ATMS algorithm explores a search space of size polynomial in the number of assumptions, even for problems which are proven to have exponential size labels. Experimental results indicate significant speedups over the standard ATMS for such problems. In addition to its improved efficiency, the BF-ATMS algorithm retains the multiple-context capability of an ATMS, and the important properties of consistency, minimality, soundness, as well as the property of bounded completeness. The usefulness of the new algorithm is demonstrated by its application to the task of consistency-based diagnosis, where dramatic efficiency improvements, with respect to the standard solution technique, are obtained

A guide to the ATM and debit card industry - 2006 update

It has been three years since we published A Guide to the ATM and Debit Card Industry. Those three years represent a very dynamic time in the industry with a number of important developments. Some trends and patterns have persisted or accelerated, while others have peaked or reversed. Still others have emerged for the first time. The purpose of this 2006 Update is to document these trends and patterns by updating the data we presented in the original book and to discuss their implications for the current and future state of the industry. ; The most important development is that the two segments of the industry, ATM and debit, are in some sense going in opposite directions. The ATM industry has matured and is relatively stagnant, with major players jockeying for position, searching for and adopting different business strategies, and adjusting to the maturation of the industry. The debit card industry, in contrast, is expanding rapidly, with new players, new partnerships, new products, and new markets. The challenge in the debit card industry is not how to cope with a maturing industry but, rather, how to preserve and enhance position and not be left behind. ; In the first part of this Update, we highlight and discuss some of the most important changes in the ATM and debit card industry. For both the ATM and debit sides of the industry, we recap and analyze changes in activity levels, industry structure, and industry pricing. We then offer some thoughts on what might lie ahead, including a discussion of fraud and data security. In the second part of this Update, we present updated versions of the 23 charts and 11 tables from the original book, adding the three or four years of additional data that have since become available.Automated tellers ; Debit cards ; Point-of-sale-systems ; Payment systems

Regulating two-sided markets: an empirical investigation

We study the effect of government encouraged or mandated interchange fee ceilings on consumer and merchant adoption and usage of payment cards in an economy where card acceptance is far from complete. We believe that we are the first to use bank- level data to study the impact of interchange fee regulation. We find that consumer and merchant welfare improved because of increased consumer and merchant adoption leading to greater usage of payment cards. We also find that bank revenues increased when interchange fees were reduced although these results are critically dependent on merchant acceptance being far from complete at the beginning and during the implementation of interchange fee ceilings. In addition, there is most likely a threshold interchange fee below which social welfare decreases although our data currently does not allow us to quantify it.Payment systems ; Consumers

CBR and MBR techniques: review for an application in the emergencies domain

The purpose of this document is to provide an in-depth analysis of current reasoning engine practice and the integration strategies of Case Based Reasoning and Model Based Reasoning that will be used in the design and development of the RIMSAT system. RIMSAT (Remote Intelligent Management Support and Training) is a European Commission funded project designed to: a.. Provide an innovative, 'intelligent', knowledge based solution aimed at improving the quality of critical decisions b.. Enhance the competencies and responsiveness of individuals and organisations involved in highly complex, safety critical incidents - irrespective of their location. In other words, RIMSAT aims to design and implement a decision support system that using Case Base Reasoning as well as Model Base Reasoning technology is applied in the management of emergency situations. This document is part of a deliverable for RIMSAT project, and although it has been done in close contact with the requirements of the project, it provides an overview wide enough for providing a state of the art in integration strategies between CBR and MBR technologies.Postprint (published version

A PROBLEM-SOLVER/TMS ARCHITECTURE FOR GENERAL CONSTRAINT SATISFACTION PROBLEMS

Constraints, in various forms, are ubiquitous to design problems. In this paper, we provide a formal characterization of a generalized constraint satisfaction problem (CSP) that can be used to model many types of design/planning problems, and the architecture of an imlemented reasoning system for solving this problem. The architecture includes a truth maintenance system (TMS) which is specifically designed to reason about the relationships expressed in the constraints as a problem solution evolves. The CSP consists of two types of data. The first type of datum corresponds to assignments that are handled by the problem solver, and the second type corresponds to constraint terms handled by the TMS. The dependency network, representing the relationships among constraint terms, is static and generally quite small, depending on the number of constraint terms. Also, justifications are never manipulated (only evaluated). This results in an architecture that makes efficient use of both space and time. The need for efficient TMSs, even though these might deal only with certain classes of problems, is underscored by the fact that general purpose TMSs have often been found to be highly inefficient for solving large problems. We also show how certain instances of the generalized CSP can be formulated as an integer programming problem, special cases of which can be solved efficiently using mathematical (integer) programming techniques.Information Systems Working Papers Serie