Paper Announcement

[Alex Simpson <als@dcs.ed.ac.uk>]

The following paper is available by anonymous FTP or over the Web


    Lambda Definability with Sums via Grothendieck Logical Relations

                 by Marcelo Fiore and Alex Simpson

    We introduce a notion of *Grothendieck logical relation* and use 
    it to characterise the definability of morphisms in *stable* bicartesian
    closed categories by terms of the simply-typed lambda calculus with 
    finite products and finite sums. Our techniques are based on concepts 
    from topos theory, however our exposition is elementary.


The paper is written in a style appropriate for the conference

    Typed Lambda-Calculi and Applications

where it is to be presented in April. However, we briefly discuss
the true categorical content of the paper, which will be further 
expanded upon in a full version of the paper (forthcoming).

The paper is available over the Web:

    http://www.dcs.ed.ac.uk/~mf/TYPES/glr.{dvi,ps}
    http://www.dcs.ed.ac.uk/~als/Research/glr.ps.gz

or by anonymous FTP:

    ftp://ftp.dcs.ed.ac.uk/pub/mf/TYPES/glr.{dvi,ps}
    ftp://ftp.dcs.ed.ac.uk/pub/als/Research/glr.ps.gz

Best wishes for a happy New Year,

Alex Simpson

-- 
Alex Simpson, LFCS, Division of Informatics, University of Edinburgh
Email: Alex.Simpson@dcs.ed.ac.uk             Tel: +44 (0)131 650 5113
FTP: ftp.dcs.ed.ac.uk/pub/als                Fax: +44 (0)131 667 7209  
URL: http://www.dcs.ed.ac.uk/home/als