Bulletin of the IGPL, Volume 3, Number 1

Contents



HyperLaTeX .dvi Files

All .dvi files are complied with hyperlatex. If you use the xhdvi previewer then you can follow the internal and external links in the volume by just clicking the mouse. The following files need to be copied to your local disc if you want to see all figures in the xdvi or xhdvi previewer or if you want to print .dvi files. They are not needed if you work with the PostScript files.

Bulletin.eps, akmanfig1.ps, akmanfig2.ps, akmanfig9.ps, akmanfig10.ps, akmanfig11.ps, akmanfig12.ps, akmanfig13.ps.


Editorial

Further steps towards a multimedia Bulletin of the IGPL

Electronic distribution of a journal like the Bulletin consisting of a collection of papers, just as any other traditional journal, can only be the beginning of a development which will revolutionize the way scientists communicate their ideas and results. Various national and international projects and project proposals currently aim at establishing the infrastructure for an electronically fully connected scientific society. As an example we cite from the project proposal `Distributed Electronic Information System for Mathematics' of the German Mathematical Society. Their plans comprise: So far, plans like this have not been discussed widely in the logic community. IGPL as a strong international community with a very large number of members could be the kernel of an organization to realize similar goals. As a very first and tiny step in this direction we therefore took a few measures to improve the electronic services of the Bulletin of the IGPL. They exploit the possibilities of WWW.

World Wide Web

World Wide Web (WWW) is an Internet-based hypertext system. It allows you to write text documents with links to other documents. These other documents may contain just plain text, compiled text like \TeX\ .dvi files or PostScript files, (PostScript is a page description language advanced printers understand. In contrast to .dvi files, which quite often still contain links to other files, PostScript files contain the full information about text and graphics. PostScript files can either be printed or previewed, under Unix for example with Ghostview.) graphics, sound and even movies. The links are addresses within the Internet. That means, a document, stored in a file system, say in England, currently read by somebody in the USA, may contain a link to another document stored in a file system in Australia. If the document is visualized with WWW viewers like Mosaic or Netscape, these links become active. Clicking on a highlighted piece of text to which such a link is attached causes the WWW system to get the other document from the remote file system and to display its contents on the screen. If this document itself is a hypertext document, it may contain further links to other documents. Another feature of WWW hypertext documents are the so-called `forms'. A form in a hypertext document consists of a specification of switches and text areas to be displayed on the screen. These forms can be filled out and their contents can be sent back to the origin of the document. There it triggers a certain action, for example an access to a database or the activation of some specific program which computes an answer and forwards the required information to the reader of the document. (You may subscribe to the Bulletin in this way.) The forms facility offers an almost unlimited variety of services.

WWW access to the Bulletin

The Bulletin has a WWW homepage which provides already some extra services including an electronic subscription form. Each volume is represented by a separate document containing the table of contents, the editorial and the abstracts of the papers in the volume. Of course there are also links to the papers themselves. As from Volume 2, Number 2 onwards we have integrated links to the authors and their departments. Browsing through the Bulletin homepage now gives you access to the author's individual WWW databases. We plan to add to each paper a link to a specific document provided by the author. This document may contain arbitrary additional information, for example comments, corrections, links to related papers or newer versions, links to corresponding software etc. This way we can maintain up to date information about all papers published in the Bulletin. Further items to be integrated into the Bulletin homepage are links to the home page of: Information about such links should be sent to Hans Jürgen Ohlbach (Executive Editor)at ohlbach@mpi-sb.mpg.de

HyperTeX papers

The papers published in the Bulletin are all written in LaTeX. From the current issue on we shall compile them with the special HyperTeX macros (see http://xxx.lanl.gov/hypertex/). These macros have two special features which allow you to turn ordinary documents into active sources of information. First of all they make the internal \label{...} -- \ref{...} links explicit. That means if the compiled LaTeX document is viewed with a special (xhdvi) previewer then the text generated by the \ref command becomes mouse sensitive. If the LaTeX source file contains for example the string ``as proved in theorem \ref{th}'', and \ref{th} is replaced by, say 3.5, then clicking on 3.5 causes the xhdvi previewer to jump to the page with Theorem 3.5. Table of contents, subject indices and the internal cross references then become the entry points for document internal links the reader can follow just by clicking a mouse. Much more important, however, is the second feature of the HyperTeX macros. It allows you to insert WWW links to other documents, in particular references to\linebreak papers accessible via WWW or FTP. This is done by the command \href{address}{text}. For example suppose there is a document accessible from http://www.mpi-sb.mpg.de/guide/staff/ohlbach/igpl/Bulletin.html (which is actually available now), and in the actual paper there should be a reference to this document, one could insert the following string in the LaTeX\ source code:

The \href{http://www.mpi-sb.mpg.de/guide/staff/ohlbach/igpl/Bulletin.html}{Bulletin}

The xhdvi previewer would highlight the string "Bulletin". Clicking on this string would cause Mosaic to be started (unless it is already active), and Mosaic itself would then get the required document and display it on the screen. In the same way all other WWW supported document forms can be accessed, in particular .dvi files and PostScript files of other papers mentioned in the bibliography. The HyperTeX features can be exploited with almost no extra work for the authors. Only the links to the external documents have to be inserted manually. The rest is done automatically. Previewers (xhdvi) supporting HyperTeX are already available, but not yet optimal. In the near future we shall provide improved ones for .dvi files and PostScript files. We are now formulating European and national project proposals to support our electronic vision. 
Dov Gabbay, Dept. of Computing, Imperial College, London}
Hans Jürgen Ohlbach. Max-Planck-Institut für Informatik, Saarbrücken
Ruy de Queiroz, Depto. de Informatica, Univ. Federal de Pernambuco, Recife


Original Articles

 On the Logic of Information Flow
 
J. Barwise 
Department of Philosophy, Sycamore Hall 026, 
Indiana University, Bloomington, IN 47405, USA. 
E-mail: barwise@phil.indiana.edu

D. Gabbay
Department of Computing, Imperial College of Science, Technology and Medicine, 
180 Queen's Gate, London SW7 2BZ, UK. 
E-mail: dg@doc.ic.ac.uk

C. Hartonas
Department of Mathematics and Computer Science, Leicester University,
University Road, Leicester LE1 7RH, UK. 
E-mail: ch25@mcs.le.ac.uk}

Abstract

This paper is an investigation into the logic of information flow. The basic perspective is that logic flows in virtue of constraints (as in \cite{barwiseperry}), and that constraints classify channels connecting particulars (as in \cite{barwiseseligman}). In this paper we explore some logics intended to model reasoning in the case of idealized information flow, that is, where the constraints involved are exceptionless. We look at this as a step toward the far more challenging task of understanding the logic of imperfect information flow, that is where the constraints admit of exceptional connections. This paper continues and amplifies work presented by the same authors in [sta4].

Get the .dvi or the PostScript file 

Situated Modeling of Epistemic Puzzles
 
M. Ersan
Computer Science Department, Brown University
Providence, Rhode Island 02912, USA. 
E-mail: me@cs.brown.edu

V. Akman
Department of Computer Engineering and Information Science, 
Bilkent University, Bilkent, Ankara 06533, Turkey. 
E-mail: akman@cs.bilkent.edu.tr

Abstract

Situation theory is a mathematical theory of meaning introduced by Jon Barwise and John Perry. It has evoked great theoretical interest and motivated the framework of a few `computational' systems. PROSIT is the pioneering work in this direction. Unfortunately, there is a lack of real-life applications on these systems and this study is a preliminary attempt to remedy this deficiency. Here, we solve a group of epistemic puzzles using the constructs provided by PROSIT.

Get the .dvi or the PostScript file 

Completely Representable Relation Algebras
 

R. Hirsch 
Department of Computing, Imperial College of Science, Technology and Medicine, 
180 Queen's Gate, London SW7 2BZ, UK. 
E-mail: rdh@doc.ic.ac.uk

Abstract

A Boolean algebra is shown to be completely representable if and only if it is atomic whereas it is shown that the class of completely representable relation algebras is not elementary.

Get the .dvi or the PostScript file 

Undecidability of the Equational Theory of Some Classes of Residuated Boolean Algebras with Operators


I. Németi, I. Sain, A. Simon
Mathematics Institute of Hungarian Academy of Sciences,
Budapest, P.O.B.\ 127, H--1364 Hungary.
E-mail: {nemeti,sain,andras}@math-inst.hu

Abstract

We show the undecidability of the equational theories of some classes of BAOs with a non-associative, residuated binary extra-Boolean operator. These results solve problems in Jipsen, Prattand Roorda. This paper complements Andréka-Kurucz-Németi-Sain-Simon where the emphasis is on BAOs with an associative binary operator.

Get the .dvi or the PostScript file 

The Essential Inadequacy of Deduction in Logic Programming


H. C. Wasserman, K. Yukawa, Z. Shen
Department of Computer Science, Queen's College, The City University of New York, 
65-30 Kissena Boulevard, Flushing, New York 11367-1597, USA.
E-mail: {wasserman,kyukawa}@qcvaxa.bitnet

Abstract

In this paper we provide very broad notions of deduction and consequence for logic programs,(so-called LP-deduction relations and LP-consequence relations), and we prove that under very modest assumptions, an LP-deduction relation will be either unsound or incomplete with respect to every LP-consequence relation.

Get the .dvi or the PostScript file 

Some Completeness Results for Propositional Conditional Logics


K. Schlechta
Laboratoire d'Informatique de Marseille, URA CNRS 1787, 
CMI, Technopôle de Château-Gombert, 
F-13453 Marseille Cedex 13, France. 
E-mail: ks@gyptis.univ-mrs.fr

Abstract

We consider three different measures of distance between classical propositional models, and provide sound and complete axiomatisations for the ensuing conditional semantics, by translating conditional formulas into equivalent classical ones.

Get the .dvi or the PostScript file

Back to the Bulletin Homepage.