Andrew Davison

Logic programming with the World-Wide Web

We introduce Logic Web, an integration of structured logic programming and the World-Wide Web. We show how LogicWeb enables programmable behaviour and state to be incorporated into Web pages, allowing them to be viewed as modules or objects with state. LogicWeb renders a Web page as a live information entity, able to determine its own response to user queries, and modify the behaviour of hyperlinks. This amalgamation of logic and the Web makes it possible to reason with Web pages, state relationships between pages, and dynamically generate pages. A prototype system is described, which extends Mosaic with LogicWeb capabilities using the Common Client Interface. In addition, we outline a client-based search tool written with LogicWeb and compare it with an existing package.

LogicWeb: Enhancing the Web with logic programming

Abstract LogicWeb is a model of the World Wide Web, where Web pages are rephrased as logic programs, and hypertext links are relationships between these programs. A logic language based on LogicWeb has been developed which supports these high-level abstractions for Web programming. We have also implemented a client-side extension to a Web browser for executing applications written in that language. The LogicWeb language is particularly suitable for coding important classes of applications, and this paper considers two in some detail: Web search, and the structuring of Web information using deductive databases. LogicWeb illustrates that logic programming possesses many advantages for writing Web applications, including the simple representation of information (e.g., as deductive databases or as logic grammars), the ability to write meta-level descriptions (e.g., of pages and the connections between pages), and the encoding of rules and heuristics necessary for “intelligent” behaviour.

CIFI: An Intelligent Agent for Citation Finding on The World-wide Web

The Web is an invaluable resource for finding citations and publications. This paper describes CIFI, a rule-based agent which autonomously finds citations on the Web, using multiple search strategies, and multiple Web-based information sources. CIFI performs heuristicguided automated browsing, utilising the Lycos search engine to find starting points for browsing.

From parlog to polka in two easy steps

In our opinion, the Object Oriented Programming (OOP) and concurrent Logic Programming (LP) paradigms offer complimentary functionality, which taken as a whole is more expressive than either separately. For this reason, the two object oriented extensions to the concurrent LP language Parlog discussed here support both paradigms.

Teaching C after Miranda

The first year of our computer science degree begins with a subject based around the lazy functional language Miranda, and is followed by a subject using ANSI C.

Secure Prolog-based mobile code

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 different 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.

Swingin’ Light Saber

When I was a youngling, I vowed to learn the ways of the BlackBerry and become a RIM-i master. I went in search of Yogurt the Wise!, Yogurt the All-Powerful!, Yogurt the Magnificent! Just plain blackberry Yogurt to his friends.

Adding a Professional Look and Feel

The most obvious element that separates a professional game from an amateur garage project isn’t the complexity of the game—it’s the use of graphics. The BB Maze example from Chapter 3 is already a complete game, but it suffers from one fatal flaw: it doesn’t look any better than the maze game people were playing on the Atari 2600 back in 1981. Nowadays, even on small devices, we can do a lot better than that.

Game Graphics and Events with MIDP and RIM Classes

The graphics and user interface (UI) classes are the place where you’ll have to choose between using the MIDP libraries and the RIM libraries. For most other types of functionality, RIM has made the choice for you by implementing either a standard JSR or a proprietary RIM library. In this chapter, you’ll learn how the philosophies of the two types of applications differ, and you’ll see how, when, and why to use either the RIM graphics/UI classes, the MIDP graphics/UI classes, or both.

Play a Live Opponent with SMS

Short Message Service (SMS) is a relatively primitive technology, originally designed in the late 1980s for devices with a lot less computing power than a BlackBerry smartphone. BlackBerry users can access their e-mail on their smartphones and typically have phone service contracts that include data transfer measured in megabytes. So it seems crazy to bother with tiny packets containing only 140 bytes of data! But there’s a reason why SMS is still a good choice for game communications: it has enormous and widespread support.