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A5  Exchange and Fusion of Information under Availability and Confidentiality Requirements in MultiAgent Systems


Biskup.JPG
Prof. Dr. Biskup, Joachim
KernIsberner.JPG
Prof. Dr. Kern-Isberner, Gabriele
Achieving both availability and confidentiality of information makes it necessary to develop and employ concepts and algorithms that handle conflicting security issues of actors and persons concerned in general. This should be possible even in situations with limited technical infrastructure in terms of time, memory, and communication. To achieve these goals, this project aims at extending data base techniques for multiagent systems, in particular, for the purpose of data mining in embedded systems.

These project ended on 12.31.2014

Confidentiality Preserving Agent Interactions

The distinguishing feature of an agent in comparison to other computing systems is its ability of autonomous decision-making driven by internal goals. An agent's decision-making relies on its belief about its environment. Therefore an agent needs to keep its beliefs up to date by perceptions through sensors or information sharing in a collaborative multiagent environment. However, an agent might be concerned about the confidentiality of some beliefs (for example, motivated or obliged by privacy issues) so that it aims to hide some of its beliefs from another agent. To enforce confidentiality, the agent must monitor and appropriately restrict its interactions with other agents. As part of this research project, we develop control procedures that an agent can employ under varying parameters:
  • Belief Representation:
    • ordinal conditional functions focus on offering expressive semantics and can be thought of as qualitative probability measures, cf. the seminal work of (Spohn/88a).
    • logic programming focus on developing powerful and fast solvers, cf. the seminal work of (Gelfond/Lifschitz/88a).
    • logical databases have a long history of research in confidentiality preservation, cf. an overview in (Biskup/2010a).
  • Types of Agent Interactions:
    • query: the sender poses a query about the recipient's belief.
    • update: the sender provides information about a change in the environment which is processed by the recipient.
    • revision: the sender provides new evidence about the present state of the environment which is processed by the recipient.
    • Further types in a setting of negotiating agents are suggested in (Biskup/etal/2008a).
  • Adversary Model: control procedures are tailored to an adversary model. For different models see the section “Epistemic Adversaries” below.

Completed Work:

  • (Biskup/Tadros/2011a) defines query and update protocols for an agent employing a propositional database. Following these protocols, the agent may refuse requests from another agent for the sake of confidentiality, correctness and reliability of information. Confidentiality may depend on the timeliness of the information. Regarding availability of information, the update transaction protocol is shown to be as cooperative and to provide as much information as possible among a discussed class of transaction protocols.
  • (Biskup/Tadros/2012) gives procedures for an agent to control its reactions to revisions and queries requested by another agent. The reacting agent bases its belief about its environment in general on a ordinal conditional function (representing the agent's expertise). Under confidentiality considerations, the reacting agent assumes that the receiver may attempt to skeptically entail confidential beliefs.

Epistemic Adversaries

In computer security, a system (here a multiagent system and its environment) is analyzed for confidentiality leaks, or more generally information leaks, from a global perspective (Halpern/ONeill/2008a). From this perspective, an agent has full knowledge of the system specification and is capable of determining and reasoning about all possible system states from its runtime information. From the perspective of an agent, however, an agent usually is able to analyze the effect of its actions on confidentiality given only incomplete information about its environment, including other agents (potential attackers). From this perspective, the agent now faces the problem how to evaluate the risk of confidentiality, only given such incomplete information. This problem is related to the research area of non-monotonic reasoning which lays the foundations of reasonable conclusions in the face of incomplete information. In evaluating confidentiality-risks, an agent may assume another “curious” agent (a potential attacker) as rational and to show individual reasoning capabilities and behavior.

Completed Work:

  • (Biskup/Tadros/2010a) relates previous work on confidentiality preserving querying of a database system, cf. (Biskup/2010a), to the global perspective of (Halpern/ONeill/2008a). It defines the notion of policy-based secrecy where in a local policy an agent may declare properties of its own state not to be ruled out by another agent. Policy-based secrecy extends the less flexible notions of secrecy presented by (Halpern/ONeill/2008a) which are not sufficiently expressive for the confidentiality requirements in database systems.

Efficient Preprocessing for Resource-bounded Agents

In previous research on database systems, there are several approaches to reduce the time-consuming dynamic control of interactions with the database system where control enforces confidentiality of information:
  1. From a database instance a view may be precomputed for a particular user such that it reveals no confidential information and is consistent with the user's a priori knowledge about the database. The user then can query the view without any further control on part of the database system (Biskup/Wiese/2008a, Biskup/Wiese/2011a).
  2. On the schema level, a relation schema can be divided into
  3. fragment schemas (by a selection of attributes) in a way that breaks sensitive relations among attributes. Then, from a database instance of the original schema fragments are generated according to the precomputed fragment schemas. Finally, these fragments are published to different parties (e.g. public and owner). See (Samarati/Vimercati/2010a).
  4. A suitable restriction of the query language
  5. can disable a database user from combining results from different queries and thereby inferring sensitive information. See (Biskup/2010a).
  6. Mixed strategies
  7. use a suitable combination of (a) precomputation (b) dynamic protocols and (c) adaptation of a database user's privilege state (including the confidentiality policy and the interaction language permitted), cf. (Biskup/2011a). In multiagent systems, such strategies are apt to adjust an appropriate balance between competing goals of an agent, such as low consumption of different resources and high cooperativeness in the collaboration with other agents.
In this research project, we aim to improve upon the existing approaches by comparing and combining the different methods.

Completed Work

  • (Preuss/etal/2011a) shows that the approach to vertical fragmentation (Samarati/Vimercati/2010a) is inference-proof as long as a user only has some a priori knowledge in terms of arbitrary unirelational and typed semantic constraints belonging to the rather general classes of so-called Equality Generating Dependencies (EGDs) or Tuple Generating Dependencies (TGDs).
  • (Biskup/2011a) adapts the confidentiality policy for a database user such that it becomes more restrictive with increasing knowledge of this user. Policy adaptation can be seen as a precomputation of relevant steps in a deduction of confidential information from the user's available knowledge.

Implementations

CIE Prototype

The CIE Prototype is a prototypical implementation of controlled interaction execution (CIE) as a frontend to the Oracle database management system. The functionality of the frontend comprises the following components:
  • the management of client-specific parameters such as the confidentiality policy and a priori knowledge;
  • a large selection of confinement methods, which range from static preprocessing of a client-specific materialized view offered for later free access to dynamic analysis of the interaction history;
  • an optimizer, which can dynamically select a currently best applicable method.

Angerona Framework

The Angerona framework is a multiagent framework dealing with confidentiality preservation. It has a modular structure defining two types of Plug-ins:
  • an Operator Plug-in for changing the behavior of the agent,
  • a Belief Base Plug-in for employing different types of knowledge representation and operators of knowledge change.
An Operator defines a functionality of an agent. For example, there is a PolicyControl Operator which changes the answer behavior of the agent in order to enforce a confidentiality policy. A collection of operators defines a Skill which is an atomic action of an agent. Both each individual agent and the simulation of the multiagent system can be configured by XML files.

Project management:

Prof. Dr. Biskup, Joachim
Prof. Dr. Kern-Isberner, Gabriele

Alumni:

Krümpelmann, Patrick
Preuß, Marcel
Dr. Tadros, Cornelia

Software:

Generator for inference-proof views of XML documents
Prototype of Signature-based Inference Control

Publications:

Albrecht/etal/2013a Albrecht, Ella and Krümpelmann, Patrick and Kern-Isberner, Gabriele. Construction of Explanation Graphs from Extended Dependency Graphs for Answer Set Programs. In Hanus, Michael and Rocha, Ricardo (editors), Post-Proceedings of the 27th Workshop on Logic Programming, No. 1306, pages 17-31, Springer, 2014.


Biskup/etal/2014a Biskup, Joachim and Kern-Isberner, Gabriele and Krümpelmann, Patrick and Tadros, Cornelia. Reasoning on Secrecy Constraints under Uncertainty to Classify Possible Actions. In Beierle, Christoph and Meghini, Carlo (editors), Proceedings of the 8th International Symposium on Foundations of Information and Knowledge Systems (FoIKS2014), Vol. 8367, pages 97-116, Springer, 2014.


Biskup/etal/2014b Biskup, Joachim and Bonatti, Piero and Galdi, Clemente and Sauro, Luigi. Optimality and Complexity of Inference-proof Data Filtering and CQE. In ESORICS 2014, Springer, 2014.


Biskup/Preuss/2014a Biskup, Joachim and Preuß, Marcel. Inference-Proof Data Publishing by Minimally Weakening a Database Instance. In Prakash, Atul and Shyamasundar, Rudrapatna (editors), Information Systems Security – 10th International Conference (ICISS) 2014, Vol. 8880, pages 30-49, Cham, Springer, 2014.


Biskup/Tadros/2014a Biskup, Joachim and Tadros, Cornelia. Idea: Towards a Vision of Engineering Controlled Interaction Execution for Information Services. In Jürjens, Jan and Piessens, Frank and Bielova, Nataliia (editors), Engineering Secure Software and Systems (ESSoS 2014), Vol. 8364, pages 35-44, Springer, 2014.


Kruempelmann/etal/2014b Krümpelmann, Patrick and Janus, Tim and Kern-Isberner, Gabriele. Angerona - A flexible Multiagent Framework for Knowledge-based Agents. In Bulling, Nils (editors), Proceedings of the 12th European Conference on Multi-Agent Systems, Vol. to appear, Springer, 2014.


Kruempelmann/Janus/2014a Krümpelmann, Patrick and Janus, Tim and Kern-Isberner, Gabriele. Angerona - A Multiagent Framework for Logic Based Agents with Application to Secrecy Preservation. No. 3, Technische Universität Dortmund, 2014.


Tadros/2013a Tadros, Cornelia. Belief Change Operations under Confidentiality Requirements in Multiagent Systems. Technische Universität Dortmund, 2014.


Biskup/2013a Biskup, Joachim. Logic-Oriented Confidentiality Policies for Controlled Interaction Execution. In Madaan, Aastha and Kikuchi, Shinji and Bhalla, Subhash (editors), DNIS 2013, Vol. 7813, pages 1-22, Springer, 2013.


Biskup/etal/2013a Merrill, Shawn and Basalp, Nilgun and Biskup,Joachim and Buchmann, Erik and Clifton, Chris and Kuijpers, Bart and Othman, Walied and Savas, Erkay. Privacy through Uncertainty in Location-Based Services. In International Conference on Mobile Data Management (MDM (2)), pages 67-72, 2013.


Biskup/Li/2013a Biskup, Joachim and Li, Lan. On Inference-Proof View Processing of XML Documents.. In IEEE Transactions on Dependable and Secure Computing, Vol. 10, No. 2, pages 99-113, 2013.


Biskup/Preuss/2013a Biskup, Joachim and Preuß, Marcel. Database Fragmentation with Encryption: Under Which Semantic Constraints and A Priori Knowledge Can Two Keep a Secret?. In Lingyu Wang and Basit Shafiq (editors), Proceedings of the Annual IFIP WG 11.3 Conference on Data and Applications Security and Privacy XXVII (DBSec 2013), Vol. 7964, pages 17-32, Springer, 2013.


Biskup/Tadros/2013a Biskup, Joachim and Tadros, Cornelia. Preserving confidentiality while reacting on iterated queries and belief revisions. In Annals of Mathematics and Artificial Intelligence, pages 1-49, 2013.


dilger/etal/2013a Dilger, Daniel and Krümpelmann, Patrick and Tadros, Cornelia. Preserving Confidentiality in Multiagent Systems - An Internship Project within the DAAD RISE Program. No. 1, Technische Universität Dortmund, 2013.


Kruempelmann/KernIsberner/2013a Krümpelmann, Patrick and Kern-Isberner, Gabriele. Secrecy preserving BDI Agents based on Answerset Programming. In Klusch, Matthias and Thimm, Matthias and Paprzycki, Marcin (editors), Proceedings of the 11th German Conference on Multi-Agent System Technologies (MATES'13), Vol. 8076, pages 124--137, Springer, 2013.


Tamargo/etal/2013a Tamargo, Luciano H. and Thimm, Matthias and Krümpelmann, Patrick and García, Alejandro J. and Falappa, Marcelo A. and Simari, Guillermo R. and Kern-Isberner, Gabriele. Credibility-based Selective Revision by Deductive Argumentation in Multi-agent Systems. In Ferme, Eduardo L. and Gabbay, Dov M. and Simari, Guillermo R. (editors), Trends in Belief Revision and Argumentation Dynamics, College Publications, 2013.


Biskup/2012a Biskup, Joachim. Inference-usability confinement by maintaining inference-proof views of an information system. In International Journal of Computational Science and Engineering, Vol. 7, No. 1, pages 17-37, 2012.


Biskup/2012b Biskup, Joachim. Dynamic policy adaptation for inference control of queries to a propositional information system. In Journal of Computer Security, Vol. 20, No. 5, pages 509-546, 2012.


Biskup/Hartmann/2012a Biskup, Joachim and Hartmann, Sven and Link, Sebastian and Lochner, Jan-Hendrik and Schlotmann, Torsten. Signature-Based Inference-Usability Confinement for Relational Databases under Functional and Join Dependencies. In Nora Cuppens-Boulahia and Fr\'ed\'eric Cuppens and Joaqu\'\in Garc\'\ia-Alfaro (editors), Data and Applications Security and Privacy XXVI - 26th Annual IFIP WG 11.3 Conference, Vol. 7371, pages 56-73, IFIP WG 11.3, Springer, 2012.


Biskup/Hartmann/2012b Biskup, Joachim and Hartmann, Sven and Link, Sebastian. Probabilistic Conditional Independence under Schema Certainty and Uncertainty. In Eyke Hüllermeier and Sebastian Link and Thomas Fober and Bernhard Seeger (editors), Scalable Uncertainty Management - 6th International Conference (SUM 2012), Vol. 7520, pages 365-378, Springer, 2012.


Biskup/Tadros/2012a Biskup, Joachim and Tadros, Cornelia. Revising Belief without Revealing Secrets. In Lukasiewicz, Thomas and Sali, Attila (editors), 7th International Symposium on Foundations of Information and Knowledge Systems (FoIKS 2012), Vol. 7153, pages 51-70, Springer, 2012.


Kruempelmann/KernIsberner/2012a Krümpelmann, Patrick and Kern-Isberner, Gabriele. Belief Base Change Operations for Answer Set Programming. In Proceedings of the 13th European Conference on Logics in Artificial Intelligence (JELIA'12), Vol. 7519, pages 294-306, Springer, 2012.


Kruempelmann/KernIsberner/2012b Krümpelmann, Patrick and Kern-Isberner, Gabriele. On Agent-based Epistemic Secrecy. In Riccardo Rossi and Stefan Woltran (editors), Proceedings of the 14th International Workshop on Non-Monotonic Reasoning (NMR'12), 2012.


Biskup/2011a Biskup, Joachim. History-dependent inference control of queries by dynamic policy adaption. In Li, Yingjiu (editors), Data and Applications Security and Privacy XXV - 25th Annual IFIP WG 11.3 Conference, DBSec 2011, Vol. 6818, pages 106-121, IFIP WG 11.3, Springer, 2011.


Biskup/Tadros/2011a Biskup, Joachim and Tadros, Cornelia. Inference-proof View Update Transactions with Minimal Refusals. In Garcia-Alfaro, Joaquin and Navarro-Arribas, Guillermo and Cuppens-Boulahia, Nora and de Capitani di Vimercati, Sabrina (editors), 6th International Workshop on Data Privacy Management, DPM 2011, Vol. 7122, pages 104-121, Springer, 2011.


Preuss/etal/2011a Biskup, Joachim and Preuß, Marcel and Wiese, Lena. On the Inference-Proofness of Database Fragmentation Satisfying Confidentiality Constraints. In Xuejia Lai and Jianying Zhou and Hui Li (editors), Proceedings of the 14th Information Security Conference (ISC 2011), Vol. 7001, pages 246-261, Springer, 2011.


  • Albrecht/etal/2013a - Construction of Explanation Graphs from Extended Dependency Graphs for Answer Set Programs
  • Biskup/etal/2014a - Reasoning on Secrecy Constraints under Uncertainty to Classify Possible Actions
  • Biskup/etal/2014b - Optimality and Complexity of Inference-proof Data Filtering and CQE
  • Biskup/Preuss/2014a - Inference-Proof Data Publishing by Minimally Weakening a Database Instance
  • Biskup/Tadros/2014a - Idea: Towards a Vision of Engineering Controlled Interaction Execution for Information Services
  • Kruempelmann/etal/2014b - Angerona - A flexible Multiagent Framework for Knowledge-based Agents
  • Kruempelmann/Janus/2014a - Angerona - A Multiagent Framework for Logic Based Agents with Application to Secrecy Preservation
  • Tadros/2013a - Belief Change Operations under Confidentiality Requirements in Multiagent Systems
  • Biskup/2013a - Logic-Oriented Confidentiality Policies for Controlled Interaction Execution
  • Biskup/etal/2013a - Privacy through Uncertainty in Location-Based Services
  • Biskup/Li/2013a - On Inference-Proof View Processing of XML Documents.
  • Biskup/Preuss/2013a - Database Fragmentation with Encryption: Under Which Semantic Constraints and A Priori Knowledge Can Two Keep a Secret?
  • Biskup/Tadros/2013a - Preserving confidentiality while reacting on iterated queries and belief revisions
  • dilger/etal/2013a - Preserving Confidentiality in Multiagent Systems - An Internship Project within the DAAD RISE Program
  • Kruempelmann/KernIsberner/2013a - Secrecy preserving BDI Agents based on Answerset Programming
  • Tamargo/etal/2013a - Credibility-based Selective Revision by Deductive Argumentation in Multi-agent Systems
  • Biskup/2012a - Inference-usability confinement by maintaining inference-proof views of an information system
  • Biskup/2012b - Dynamic policy adaptation for inference control of queries to a propositional information system
  • Biskup/Hartmann/2012a - Signature-Based Inference-Usability Confinement for Relational Databases under Functional and Join Dependencies
  • Biskup/Hartmann/2012b - Probabilistic Conditional Independence under Schema Certainty and Uncertainty
  • Biskup/Tadros/2012a - Revising Belief without Revealing Secrets
  • Kruempelmann/KernIsberner/2012a - Belief Base Change Operations for Answer Set Programming
  • Kruempelmann/KernIsberner/2012b - On Agent-based Epistemic Secrecy
  • Biskup/2011a - History-dependent inference control of queries by dynamic policy adaption
  • Biskup/Tadros/2011a - Inference-proof View Update Transactions with Minimal Refusals
  • Preuss/etal/2011a - On the Inference-Proofness of Database Fragmentation Satisfying Confidentiality Constraints

Final Thesis:

Wierzoch/2014a Wierzoch, Pia. Aktualisierung von Wissen unter Vertraulichkeitsanforderungen. TU Dortmund University, LS 6 - Information Systems and Security, 2014.


Dudenhefner/2013a Dudenhefner, Andrej. Veröffentlichung von häufig vorkommenden Mustern in relationalen Datenbanken unter Vertraulichkeitsanforderungen. TU Dortmund University, LS 6 - Information Systems and Security, 2013.


Homann/2013a Homann, Sebastian. Argumentationsbasierte selektive Revision erweiterter logischer Programme. TU Dortmund University, LS1 - Information Engineering, 2013.


Janus/2013a Janus, Tim. Resource-bounded Planning of Communication under Confidentiality Constraints for BDI Agents. TU Dortmund University, LS1 - Information Engineering, 2013.


Albrecht/2012a Albrecht, Ella. Abhängigkeitsgraphen und Erklärungen für die Antwortmengen Programmierung. TU Dortmund University, LS1 - Information Engineering, 2012.


Gonzalez/2012a Benet Gonzalez, Lorenzo. Implementierung von inferenzsicheren Sichtänderungen mit nachfolgenden Sichterneuerungen. TU Dortmund University, LS 6 - Information Systems and Security, 2012.


Hoelzgen/2012a Hölzgen, Daniel. Ein Multiagenten-Ansatz zur Vertraulichkeitsbewahrung bei der Erhebung von Fahrzeugdaten für die Verkehrsprognose. TU Dortmund University, LS1 - Information Engineering, 2012.


Mucha/2012a Mucha, Viktor. Werkzeuge und Optimierung sowie Erweiterungen für die Signatur-basierte Inferenzkontrolle relationaler Anfragen. TU Dortmund University, LS 6 - Information Systems and Security, 2012.


Quermann/2012a Quermann, Kim. Mergen von Kontextinformation unter Vertraulichkeitsanfoderungen. TU Dortmund University, LS 6 - Information Systems and Security, 2012.


Sudhölter/2012a Sudhölter, Tobias. Evaluation von motivationsbasierten Agenten. TU Dortmund University, LS1 - Information Engineering, 2012.


Böhmer/2011a Böhmer, Mirja. Evaluation von Ansätzen zur Wissensänderung von ASP Wissensbasen. TU Dortmund University, LS1 - Information Engineering, 2011.


Schlotmann/2011a Schlotmann, Torsten. Kontrollierte Auswertung relationaler Anfragen mit Hilfe von aus Integritätsbedingungen erzeugten Signaturen. TU Dortmund University, LS 6 - Information Systems and Security, 2011.


  • Wierzoch/2014a - Aktualisierung von Wissen unter Vertraulichkeitsanforderungen
  • Dudenhefner/2013a - Veröffentlichung von häufig vorkommenden Mustern in relationalen Datenbanken unter Vertraulichkeitsanforderungen
  • Homann/2013a - Argumentationsbasierte selektive Revision erweiterter logischer Programme
  • Janus/2013a - Resource-bounded Planning of Communication under Confidentiality Constraints for BDI Agents
  • Albrecht/2012a - Abhängigkeitsgraphen und Erklärungen für die Antwortmengen Programmierung
  • Gonzalez/2012a - Implementierung von inferenzsicheren Sichtänderungen mit nachfolgenden Sichterneuerungen
  • Hoelzgen/2012a - Ein Multiagenten-Ansatz zur Vertraulichkeitsbewahrung bei der Erhebung von Fahrzeugdaten für die Verkehrsprognose
  • Mucha/2012a - Werkzeuge und Optimierung sowie Erweiterungen für die Signatur-basierte Inferenzkontrolle relationaler Anfragen
  • Quermann/2012a - Mergen von Kontextinformation unter Vertraulichkeitsanfoderungen
  • Sudhölter/2012a - Evaluation von motivationsbasierten Agenten
  • Böhmer/2011a - Evaluation von Ansätzen zur Wissensänderung von ASP Wissensbasen
  • Schlotmann/2011a - Kontrollierte Auswertung relationaler Anfragen mit Hilfe von aus Integritätsbedingungen erzeugten Signaturen

Preliminary Work:

Biskup/2010a Joachim Biskup. Usability confinement of server reactions maintaining inference-proof client views by controlled interaction execution. In Databases in Networked Information Systems, DNIS 2010, Vol. 5999, pages 80-106, Springer, 2010.


Biskup/Tadros/2010a Joachim Biskup and Cornelia Tadros. Policy-Based Secrecy in the Runs & Systems Framework and Controlled Query Evaluation. In Isao Echizen and Noboru Kunihiro and Ryoichi Sasaki (editors), IWSEC 2010 (Short Papers), Information Processing Society of Japan (IPSJ), 2010.


Biskup/2009a Joachim Biskup. Security in Computing Systems -- Challenges, Approaches and Solutions. Springer, 2009.


Biskup/etal/2009a Joachim Biskup and Christian Gogolin and Jens Seiler and Torben Weibert. Requirements and Protocols for Inference-Proof Interactions in Information Systems. In European Symposium on Research in Computer Security, ESORICS 2009, Vol. 5789, pages 285-302, Springer, 2009.


Falappa/etal/2009a Marcelo Alejandro Falappa and Gabriele Kern-Isberner and Guillermo Ricardo Simari. Belief Revision and Argumentation Theory. In Simari, G.R. and Rahwan, I. (editors), Argumentation in Artificial Intelligence, pages 341--360, Springer, 2009.


Biskup/etal/2008a Joachim Biskup and Gabriele Kern-Isberner and Matthias Thimm. Towards Enforcement of Confidentiality in Agent Interactions. In Maurice Pagnucco and Michael Thielscher (editors), Proceedings of the 12th International Workshop on Non-Monotonic Reasoning (NMR'08), pages 104-112, Sydney, Australia, University of New South Wales, Technical Report No. UNSW-CSE-TR-0819, 2008.


Biskup/Weibert/2008a Joachim Biskup and Torben Weibert. Keeping secrets in incomplete databases. In Int. Journal of Information Security, Vol. 7, No. 3, pages 199-217, 2008.


Biskup/Wiese/2008a Joachim Biskup and Lena Wiese. Preprocessing for controlled query evaluation with availability policy. In Journal of Computer Security, Vol. 16, No. 4, pages 477-494, 2008.


KernIsberner/2008a Gabriele Kern-Isberner. Linking iterated belief change operations to nonmonotonic reasoning. In G. Brewka and J. Lang (editors), Proceedings 11th International Conference on Knowledge Representation and Reasoning, KR'2008, pages 166-176, Menlo Park, CA, AAAI Press, 2008.


Kruempelmann/etal/2008a Krümpelmann, Patrick and Thimm, Matthias and Ritterskamp, Manuela and Kern-Isberner, Gabriele. Belief Operations for Motivated BDI Agents. In Lin Padgham and David C. Parkes and Joerg P. Müller and Simon Parsons (editors), Proceedings of the 7th International Conference on Autonomous Agents and Multiagent Systems (AAMAS 2008), pages 421-428, Estoril, Portugal, 2008.


Thimm/KernIsberner/2008a Matthias Thimm and Gabriele Kern-Isberner. A Distributed Argumentation Framework using Defeasible Logic Programming. In Philippe Besnard and Sylvie Doutre and Anthony Hunter (editors), Proceedings of the 2nd International Conference on Computational Models of Argument (COMMA'08), No. 172, pages 381-392, Toulouse, France, IOS Press, 2008.


Biskup/Bonatti/2007a Joachim Biskup and Piero A. Bonatti. Controlled query evaluation with open queries for a decidable relational submodel. In Annals of Mathematics and Artificial Intelligence, Vol. 50, No. 1-2, pages 39-77, 2007.


KernIsberner/Fisseler/2004a G. Kern-Isberner and J. Fisseler. Knowledge Discovery by Reversing Inductive Knowledge Representation. In Proceedings of the Ninth International Conference on the Principles of Knowledge Representation and Reasoning, KR-2004, pages 34-44, AAAI Press, 2004.