Date: Wed, 16 Jan 2013 17:42:34 +0100
Subject: 18 January 2013, 11:00, L017: Negotiated Transformations
From: Vadim Zaytsev
To: PEM

Dear environmentalists,

Let me wish you all a happy new year, filled with many exciting
presentations! The new season of the PEM Colloquium will start this
week with a presentation by yours truly on a topic reported at the
Extreme Modelling Workshop and submitted yesterday to the Journal of
Object Technology.

Instead of using megamodels, the presentation will incorporate a
fragment of a Doctor Who episode.


 Date: 18 January 2013
 Time: 11:00-12:00
 Room: CWI, L017
 Speaker: Vadim Zaytsev
 Title: Negotiated Transformations
 Abstract: see below

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        Negotiated Transformations

The classic computation model for many kinds of transformations
involves checking the applicability condition, then applying the rules
for actual rewriting, and possibly validating a postcondition. In
practice, such preconditions and often compromised by changes to the
input of the transformation. Grammar transformations are one of the
most rigid in that sense, which leads to the whole transformation
chain becoming inapplicable if the input is adjusted (which can happen
for many reasons).

Instead of failing and forcing the user to coevolve the transformation
script, we could apply a different computation model, where the result
of violating a precondition is not a failure, but a recommendation of
feasible alternatives. (Sort of, going from "Cannot find X" to "Cannot
find X, did you mean Y?") Then, a series of negotiations can lead to
successfully applying the adjusted transformation. The talk will
include introducing two conceptual kinds of adaptability, pieces of
code in Prolog, Rascal and Algol, and grammars.
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              http://event.cwi.nl/pem/calendar.html
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Yours,
     Vadim.