Conference Report: KR 2012

The 12th International Conference on Principles of Knowledge Representation and Reasoning, KR 2012, was held in Rome, Italy, from June 10-14, 2012.  It was collocated with several other events: this year’s Workshop on Nonmonotonic Reasoning (NMR), the Description Logic Workshop (DL) and the Italian Convention on Computational Logic (CILC) which took place before respectively were overlapping with the KR pre-day; the First International Workshop on Knowledge-intensive Business Processes (KiBP’12) and the Italian Symposium on Artificial Intelligence (IA*AI), which were overlapping with the last day respectively took place after KR 2012.

The KR 2012 conference, chaired by Gerd Brewka, was hosted by the University of Rome “La Sapienza” (under the lead of Giuseppe de Giacomo and Marco Schaerf) and took place in building of the university, providing a nice and friendly atmosphere, with a gorgeous lounge on the roof top where the coffee breaks took place and lunch was served, but also with some presentation challenges for the speakers (lecture halls equipped with latest technology, featuring two large screens at an angle behind the speakers).

The program of the conference, was rich and included four tutorials, five invited talks, 71 technical papers, and a Doctoral Consortium, which was organized by Esra Erdem, Sabanci University, Turkey, and Frank Wolter, University of Liverpool, UK.  The list of topics addressed at the conference were as usual diverse and covered a broad range of substantial research areas.

As a warm-up, the tutorials were given on the pre-day of the conference (Sunday, June 10), and offered the participants the opportunity to learn about quite diverse topics that are of interest for the KR researcher and practitioner:

  • “IBM Watson,” presented by Alfio M. Gliozzo (IBM Watson Research Center, USA),
  • “Graph-Based Methods for Problem Decomposition,” by Georg Gottlob (Univ. Oxford, UK), Gianluigi Greco and Francesco Scarcello (Univ. Calabria, Italy);
  • “Introduction to Social Choice” by Jerome Lang (Dauphin Univ. Paris, France), and
  • “Modeling and Solving in Answer Set Programming” by Torsten Schaub (Univ. Potsdam, Germany).

Material of these tutorials is available from the webpages of the conference (see below).
The conference started on Monday, June 11, with a lecture in remembrance of John McCarthy – one of the greatest minds in computer science, who is recognized by many as the founder of AI and KR, passed away following a rich and productive career that spanned nearly 50 years.  Leora Morgenstern reviewed in her lecture “Through the Lens of Drosophila: John McCarthy’s Quest for Human-Level Artificial Intelligence” the vitae of this pioneer and distinct scientist, his long-lasting achievements and contributions, and did not miss to point out social engagement that was less known – also people who thought to have known everything about McCarthy were impressed.

A highlight of KR 2012, the more from the logic programming perspective, was the 2012 Great Moments in KR Lecture, “Logic Programming Solution to the Frame Problem” by Vladimir Lifschitz (Univ. Texas, USA). He pointed out the versatility and the usefulness of logic programming, extended with stable negation, to provide an elegant solution to the frame problem that had plagued the AI community for quite some time. The audience enjoyed the presentation and one had the feeling that they left educated after Lifschitz’s brilliant talk. After the talk, a number of people joined for a dinner party to celebrate the 65th birthday of the speaker, who was presented in stage with a Festschrift in honor of this milestone, to which a number of people from out community have contributed; unfortunately, it was just a facsimile at this point, as the book is still in press.

The other invited lectures at KR 2012 were given by Craig Boutilier (Univ. Toronto, Canada), “Preference Elicitation and Preference Learning in Social Choice: New Foundations for Group Recommendation”; by Maurizio Lenzerini (Univ. Rome “La Sapienza”), “Ontology-based Data Management: Present and Future”; and by Moshe Vardi (Rice Univ., USA) “The Rise and Fall of Linear Temporal Logic.” The lecture hall was packed with people to listen what these distinguished scientists will tell.  All these talks were excellent and the people apparently enjoyed the presentations. In particular, Vardi’s presentation was great fun and one could not believe that deep theoretic research entangled with industrial application can be told in such an entertaining way. Vardi’s story about how A. Prior came about to invent tense logic (“Prior’s dream”), and the speaker’s interactions with industry to flesh out a formalism for temporal specification have
no counterpart in the list of invited talks that the reporter has experienced so far.

As regards the contributed papers, the most popular topics for submission of technical papers to KR 2012 included answer set programming; description logics; nonmonotonic reasoning; argumentation; belief merging, revision, and update; and KR and databases. In fact, among the accepted 53 regular and 18 short papers, two larger topics could be identified: logic programming, with a skew on answer set programming and comprising foundation and applications in diverse areas, and description logics, with a strong focus in query answering.  The papers were arranged in parallel sessions on the following topics:

  • Abstraction and Diagnosis,
  • Answer Set Programming and Logic Programming,
  • Argumentation,
  • Automated Reasoning and Computation,
  • Belief Revision (I+II),
  • Decision Making and Reasoning about Preferences,
  • Description Logics (I+II),
  • Epistemic Logics,
  • Inconsistency-Tolerant and Similarity-Based Reasoning,
  • Knowledge Representation and Knowledge Based Systems,
  • Reasoning about Actions and Planning,
  • Reports from the Field,
  • Spatial and Temporal Reasoning,
  • Uncertainty.

The paper “Ambiguous Language and Differences in Beliefs” by Joseph Y. Halpern and Willemien Kets was honored with the KR Ray Reiter Best Paper Award of KR 2012, and the paper “Complexity-Sensitive Decision Procedures for Abstract Argumentation” by Wolfgang Dvorak, Matti Järvisalo, Johannes P. Wallner and Stefan Woltran was selected for the KR 2012 Distinguished Student Paper Award – this was the first time such an award was granted, and in future editions of KR will be institutionalized as Marco Cadoli Award in remembrance of this great young KR scholar.

As mentioned above, one session – “Answer Set Programming and Logic Programming” – was entirely devoted to this subject, and it included four papers with a foundational character:

  • “Logic Programs with Intensional Functions” by Vladimir Lifschitz;
  • “Stable Models of Formulas with Intensional Functions”, by Michael Bartholomew and Joohyung Lee;
  • “Answer Set Programming via Mixed Integer Programming” by Guohua Liu, Tomi Janhunen and Ilkka Niemelä; and
  • “On the Small-Scope Hypothesis for Testing Answer-Set Programs” by Johannes Oetsch, Michael Prischink, Jörg Pührer, Martin Schwengerer, and Hans Tompits.

Further foundational papers were located in session dedicated to other major topics, including the papers

  • “Stable Models in Generalized Possibilistic Logic” by  Didier Dubois, Henri Prade and Steven Schockaert,
  • “Robust Equivalence Models for Semantic Updates of Answer-Set Programs” by Martin Slota and Joao Leite; and
  • “Paraconsistent Hybrid Theories” by Michael Fink.

Other papers were devoted to systems and applications respectively generalization of Answer Set Programming, including:

  • “Strong Equivalence of Qualitative Optimization Problems” by Wolfgang Faber, Miroslaw Truszczynski, Stefan Woltran;
  • “JASP: A Framework for Integrating Answer Set Programming with Java” by Onofrio Febbraro, Giovanni Grasso, Nicola Leone and Francesco Ricca;
  • “Declarative Entity Resolution via Matching Dependencies and Answer Set Programs” by Zeinab Bahmani, Leopoldo Bertossi, Solmaz Kolahi, and Laks V.S. Lakshmanan;
  • “From Knowledge Represented in Frame-Based Languages to Declarative Representation and Reasoning via ASP” by Chitta Baral, Shanshan Liang; and
  • “Specifying and Reasoning with Underspecified Knowledge Bases Using Answer Set Programming” by Vinay K. Chaudhri and Tran Cao Son.

Besides the regular papers, which were presented in 30 minutes slots, short papers (which had allotted less space in the proceedings) were an integral part of the conference. These papers were given a 10 minutes presentation slot in two parallel short paper sessions, plus in addition a poster presentation, which gave the audience the opportunity to discuss with the authors in a dedicated poster session.

Among the 18 short papers, the following six fall into logic programming:

  • “Forgetting in Logic Programs under Strong Equivalence” by Yisong Wang, Yan Zhang, Yi Zhou and Mingyi Zhang;
  • “Towards Parallel Nonmonotonic Reasoning with Billions of Facts” by Ilias Tachmazidis, Grigoris Antoniou, Giorgos Flouris and Spyros Kotoulas;
  • “Worst-case Optimal Reasoning with Forest Logic Programs” by Cristina Feier;
  • “Achieving completeness in bounded model checking of action theories in ASP”, by Laura Giordano, Alberto Martelli and Daniele Theseider Duprè;
  • “Solving Puzzles Described in English by Automated Translation to Answer Set Programming and Learning how to do that Translation” by Chitta Baral and Juraj Dzifcak; and
  • “Stream Reasoning with Answer Set Programming” by Martin Gebser, Torsten Grote, Roland Kaminski, Philipp Obermeier, Orkunt Sabuncu and Torsten Schaub.

KR 2012 was a vibrant forum of discussion, and through the lens of Logic Programming a meeting that shows that relevance and importance of research in this area for Knowledge Representation and Reasoning, in appreciation of the wider community. The conference was well attended (there were some 190 registered participants) and people seemed to have enjoyed the meeting very much: the venue, the technical program, but also the social program with the visit to Villa Adrian in Tivoli, approximately 30 kilometers northeast of Rome,   where an interesting guided tour through emperor Hadrian’s (117-138) residence (which was more a pendant of the Forbidden City in Beijing than a plain villa) was followed by a nice dinner featuring Roman specialties at a restaurant close to the historic area.

The next edition of KR will be in 2014, under the umbrella of the Vienna Summer of Logic in July 2014, which also covers the Federated Logic Conference (FLoC) 2014 which ICLP will be part of; thus KR and ICLP will be in the same place, strengthening the link between the two meetings. The excellent work of the 2012 organizing committee has set a high standard for the Vienna organization team!

For more information about KR 2012, and material for download (including the tutorials and invited talks), visit or see the proceedings of the conference, which where published by AAAI Press.