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    ELECTRONIC NEWSLETTER ON  REASONING ABOUT ACTIONS AND CHANGE        
Issue 99014             Editor: Erik Sandewall             6.5.1999
         Back issues available at http://www.etaij.org/rac/
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                    *********  TODAY  *********

With this issue we confirm the acceptance of two submitted reference 
articles: the one by Michael Thielscher and the one by Michael Gelfond
and Vladimir Lifschitz.

For Thielscher's article we had an animated discussion between the two
referees some time ago. No additional contribution has arrived for that
debate, and an analysis of the arguments and the article led to the
conclusion that the article should be accepted without reservations,
although with an option for the author to revise the article in order
to take some of the referee suggestions into account.

For the article by Gelfond and Lifschitz the two anonymous referees 
have made some remarks, but no suggestions for changes. The article is
accepted without reservations.



              *********  ETAI PUBLICATIONS  *********

            ---  DISCUSSION ABOUT RECEIVED ARTICLES  ---

The following debate contributions (questions, answers, or comments)
have been received for articles that have been submitted to the ETAI and
which are presently subject of discussion. To see the full context,
for example, to see the question that a given answer refers to, or to
see the article itself or its summary, please use the web-page version 
of this Newsletter.

        ========================================================
        |  AUTHOR: Michael Gelfond and Vladimir Lifschitz
        |  TITLE:  Action Languages
        |  PAPER:  http://www.ep.liu.se/ea/cis/1998/016/
        |  REVIEW: http://www.ida.liu.se/ext/etai/ra/rac/015/
        ========================================================

--------------------------------------------------------
|  FROM: Anonymous Referee 1
--------------------------------------------------------

I have checked the article against the refereeing criteria for
reference articles:

1. *Does the article represent a tradition or "approach" where there
is already a sufficient volume of work in the field?*

Yes. The article describes a family of six action languages: the
action description languages A, B, and C and the action query languages
P, Q, and R, related by various subsumption relationships. The common
semantics for these is defined using transition systems. This structure
of languages looks a bit forbidding at first, but it is systematic and
easy to grasp.

Some other action languages that have been introduced previously in
time (such as AR0 and AR) are not covered in this article. An
explanation of how they relate to the languages described here would be
helpful.

2. *Does the article concisely specify the assumptions, motivations,
and notations used in that approach? Does it correctly capture the 
assumptions, etc. that have been used and are being used?*

Yes.

3. *Would reading the present article enable one to skip the
introductory definitions section of many previously published articles
that used the approach?*

Yes. (Note however that some journal articles also contain a general 
introduction to the 'frame problem' in reasoning about actions, and
the present article does not provide that background).

4. *Is the article also concise in the sense that it does not contain
a lot of material that is unnecessary for the above criteria?*

Yes.

5. *Is the article pedagogical and sufficiently easy to read, but at
the same time precise and correct?*

Yes.

--------------------------------------------------------
|  FROM: Anonymous Referee 2
--------------------------------------------------------

The article is both concise and easy to read, and satisfies the 
requirements that have been set for reference articles. I recommend 
that it shall be accepted for publication.

I do have a question to the authors however. When they introduced 
action languages in 1993 (in the article in the Journal of Logic 
Programming), they proposed to "describe" a particular methodology for
representing action as a translation from the action language to a
"target language", in particular logic programming language. The formal
results in many of the following papers have often concerned properties
of a translation of an action language into circumscribied situation
calculus (for example, the KR 1994 paper and the AI Journal 1997
paper), although of course the semantics of the action language has
always been defined using transition systems.

The present article does not however contain any reference to such 
translations. Does this indicate that translations are no longer 
considered an essential part of the approach, or is it just the result
of factoring out the formal definitions of the language in terms of
syntax and semantics, omitting other aspects?


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