We propose a two-level model for the World Wide Web: Web pages are stored at the first level, and the links between them pass through a link abstraction layer. This extra layer permits processing to be carried out as part of link traversal, thereby increasing the expressiveness of links beyond direct connection between pages. This mechanism is implemented using LogicWeb, which allows Web pages to be treated as logic programs. One advantage of LogicWeb is that it enables conceptual Web structures to be coded in the abstraction layer which are amenable to sophisticated querying and automated reasoning. Another benefit is that it allows the easy specification of rules which model the nondeterministic and unpredictable nature of link activation in the Web. 1 Introduction The Web's basic link mechanism is uni-directional, with fixed source and destination pages. When a page is retrieved, it is simply displayed. We extend the expressiveness of links by proposing a two-level model for the We...

. We describe Webstream, a concurrent stream-based scripting language for client-side web programming. Webstream encapsulates web documents as active streams executing in lightweight threads, permitting operations to be carried out lazy-evaluation style while documents are still being transparently fetched or retried. Streams can be pipelined through lters which perform transformations such as parsing raw text into HTML tags, extracting subset streams based on arbitrary computable patterns within tags or regular expression-like sequences of tags, and combining or splitting streams in various ways. These facilities allow the easy construction of a wide variety of web applications, including crawlers, comparison-shopping agents, and meta-search engines. 1 Introduction With the emergence of the web as a ubiquitous feature of the computer landscape, a new niche of web programming has been created. Web programs are applications whose native domain of operation is the reading, p...

This paper indicates how dierent logic programming technologies can underpin an architecture for distributed knowledge management in which higher throughput in information supply is achieved by a (semi-)automated solution to the more challenging problem of knowledge creation. The paper rst proposes working denitions of the notions of data, knowledge and information in purely logical terms, and then shows how existing technologies can be combined into an inference engine, referred to as a knowledge, information and data engine (KIDE), integrating inductive and deductive capabilities. The paper then describes an architecture for KIDEs, briey introduces the notion of virtual organizations and uses the set up stage of virtual organizations to exemplify the valueadding potential of KIDEs in knowledge management contexts.

In this paper, we propose a method for approximate reasoning within an abductive logic programming setting. Our investigation is motivated by applying abductive reasoning to the problem of searching the web. Retrieval of user-relevant information is modeled as the task of generating abductive solutions (explanations) to a search query. In order to rule out (logically relevant) solutions (web sites) if they are uninteresting to the user, factual relevance criteria are applied. The main contribution of our paper is a well-founded method of restricting the set of abductive solutions in a way that user-relevant information (i) can be retrieved even if the knowledge base is partly explored, and (ii) is preserved over activated hyperlinks. Topic areas: LP-based net search tools and spiders. 1 Introduction and Motivation As AI research shifts from solving `toy problems' towards real-world applications, methods are called for that reduce the computational complexity inherent in virtually all...

LogicWeb mobile code consists of Prolog-like rules embedded in Web pages, thereby adding logic programming behaviour to those pages. Since LogicWeb programs are downloaded from foreign hosts and executed locally, there is a need to protect the client from buggy or malicious code. A security model is crucial for making LogicWeb mobile code safe to execute. This paper presents such a model, which supports programs of varying trust levels by using dierent resource access policies. The implementation of the model derives from an extended operational semantics for the LogicWeb language, which provides a precise meaning of safety.