Moderated by Erik Sandewall.

Michael Gelfond and Vladimir Lifschitz Action Languages

The article mentioned above has been submitted to the Electronic Transactions on Artificial Intelligence, and the present page contains the review discussion. Click here for more explanations and for the webpage of theauthors: Michael Gelfond and Vladimir Lifschitz. Overview of interactions N:o Question Answer(s) Continued discussion 1 6.5.1999  Anonymous Referee 1     2 6.5.1999  Anonymous Referee 2       Q1. Anonymous Referee 1 (6.5.1999): 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. Q2. Anonymous Referee 2 (6.5.1999): 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?   Background: Review Protocol Pages and the ETAI This Review Protocol Page (RPP) is a part of the webpage structure for the Electronic Transactions on Artificial Intelligence, or ETAI. The ETAI is an electronic journal that uses the Internet medium not merely for distributing the articles, but also for a novel, two-stage review procedure. The first review phase is open and allows the peer community to ask questions to the author and to create a discussion about the contribution. The second phase - called refereeing in the ETAI - is like conventional journal refereeing except that the major part of the required feedback is supposed to have occurred already in the first, review phase. The referees make a recommendation whether the article is to be accepted or declined, as usual. The article and the discussion remain on-line regardless of whether the article was accepted or not. Additional questions and discussion after the acceptance decision are welcomed. The Review Protocol Page is used as a working structure for the entire reviewing process. During the first (review) phase it accumulates the successive debate contributions. If the referees make specific comments about the article in the refereeing phase, then those comments are posted on the RPP as well, but without indicating the identity of the referee. (In many cases the referees may return simply an " accept" or " decline" recommendation, namely if sufficient feedback has been obtained already in the review phase).