# Pascal Bercher

2003 bis 2009 studierte ich Informatik (Diplom) an der Albert-Ludwigs-Universität Freiburg im Breisgau. Meine Vertiefungsrichtung war Künstliche Intelligenz (KI), meine Subvertiefung innerhalb der KI war/ist das Gebiet der Handlungsplanung. Mein Nebenfach war Kognitionswissenschaft (KW); auch privat bin ich an Psychologie und der Philosophie des Geistes (beides sind Teildisziplinen der KW) interessiert.

Seit Juli 2009 bin ich Doktorand und arbeite in dem Sonderforschungsbereich Transregio 62 (SFB-TRR-62), Teilprojekt A1 (Adaptive Planung und Entscheidungsfindung).

# Kontakt

• Pascal.Bercher(at)uni-ulm.de
• Telefon:   +49 (0)731/50-24118
• Telefax:   +49 (0)731/50-24119
• ## Postanschrift

• Pascal Bercher
• Universität Ulm
• Institut für Künstliche Intelligenz
• D-89069 Ulm
• ## Büro

• James-Franck-Ring
• Gebäude O27, 4. Niveau
• Raum 446

# Publikationen

Jahr:
Alle :: 2008, ... , 2012, 2013, 2014, 2015
Präferenzen:
Referenzen pro Seite: Zeige Schlüsselwörter Zeige Zusammenfassung
Referenzen
 Nothdurft, Florian, Behnke, Gregor, Bercher, Pascal, Biundo, Susanne und Minker, Wolfgang The Interplay of User-Centered Dialog Systems and AI Planning Proceedings of the 16th Annual Meeting of the Special Interest Group on Discourse and Dialogue (SIGDIAL) , Seite 344--353. Herausgeber: Association for Computational Linguistics, September 2015 Marker: SFB-TRR-62,Planning Zusammenfassung: Technical systems evolve from simple dedicated task solvers to cooperative and competent assistants, helping the user with increasingly complex and demanding tasks. For this, they may proactively take over some of the users responsibilities and help to find or reach a solution for the user’s task at hand, using e.g., Artificial Intelligence (AI) Planning techniques. However, this intertwining of user-centered dialog and AI planning systems, often called mixed-initiative planning (MIP), does not only facilitate more intelligent and competent systems, but does also raise new questions related to the alignment of AI and human problem solving. In this paper, we describe our approach on integrating AI Planning techniques into a dialog system, explain reasons and effects of arising problems, and provide at the same time our solutions resulting in a coherent, userfriendly and efficient mixed-initiative system. Finally, we evaluate our MIP system and provide remarks on the use of explanations in MIP-related phenomena. Behnke, Gregor, Schiller, Marvin, Ponomaryov, Denis, Nothdurft, Florian, Bercher, Pascal, Minker, Wolfgang, Glimm, Birte und Biundo, Susanne A Unified Knowledge Base for Companion-Systems - A Case Study in Mixed-Initiative Planning Proceedings of the International Symposium on Companion Technology (ISCT 2015) 2015 Schlüsselwörter: SFB-TRR-62,Planning,AutomatedReasoning Marker: SFB-TRR-62,Planning,AutomatedReasoning Zusammenfassung: Companion systems aim to extend the abilities of ordinary technical systems, for instance by modeling the user's situation, by recognizing the user's intentions, and by being able to interact with the user and to adapt to her/him. Such a system depends on planning capabilities to determine which actions are necessary to achieve a particular goal. In many situations it may not be appropriate for a companion system to develop plans on its own, but instead it has to integrate the user while creating the plan, i.e., it needs to be mixed-initiative. Based on earlier work, we demonstrate how a central knowledge base for a mixed-initiative planning system can be designed. We outline various benefts our approach brings to bear within a companion system. Lastly, we present several requests a user might issue towards the mixed-initiative planning system and how they can be answered by harnessing the knowledge base. Behnke, Gregor, Ponomaryov, Denis, Schiller, Marvin, Bercher, Pascal, Nothdurft, Florian, Glimm, Birte und Biundo, Susanne Coherence Across Components in Cognitive Systems – One Ontology to Rule Them All Proceedings of the 25th International Joint Conference on Artificial Intelligence (IJCAI 2015) Herausgeber: AAAI Press, 2015 Marker: SFB-TRR-62,Planning,AutomatedReasoning Zusammenfassung: The integration of the various specialized components of cognitive systems poses a challenge, in particular for those architectures that combine planning, inference, and human-computer interaction (HCI). An approach is presented that exploits a single source of common knowledge contained in an ontology. Based upon the knowledge contained in it, specialized domain models for the cognitive systems’ components can be generated automatically. Our integration targets planning in the form of hierarchical planning, being well-suited for HCI as it mimics planning done by humans. We show how the hierarchical structures of such planning domains can be (partially) inferred from declarative background knowledge. The same ontology furnishes the structure of the interaction between the cognitive system and the user. First, explanations of plans presented to users are enhanced by ontology explanations. Second, a dialog domain is created from the ontology coherent with the planning domain. We demonstrate the application of our technique in a fitness training scenario. Bercher, Pascal Hybrid Planning -- Theoretical Foundations and Practical Applications Doctoral Consortium at ICAPS 2015 2015 Marker: SFB-TRR-62,Planning Zusammenfassung: The thesis presents a novel set-theoretic formalization of (propositional) hybrid planning – a planning framework that fuses Hierarchical Task Network (HTN) planning with Partial-Order Causal-Link (POCL) planning. Several sub classes thereof are identified that capture well-known problems such as HTN planning and POCL planning. For these problem classes, the complexity of the plan-existence problem is investigated, i.e., the problem of deciding whether there exists a solution for a given planning problem. For solving the problems of the respective problem classes, a hybrid planning algorithm is presented. Its search is guided by informed heuristics. Several such heuristics are introduced, both for POCL planning problems (i.e., problems without task hierarchy) and for hybrid planning problems (i.e., heuristics that are "hierarchy-aware"). Behnke, Gregor, Bercher, Pascal, Biundo, Susanne, Glimm, Birte, Ponomaryov, Denis und Schiller, Marvin Integrating Ontologies and Planning for Cognitive Systems Proceedings of the 28th International Workshop on Description Logics (DL 2015) Herausgeber: CEUR Workshop Proceedings, 2015 Marker: AutomatedReasoning, Planning, SFB-TRR-62 Zusammenfassung: We present an approach for integrating ontological reasoning and planning within cognitive systems. Patterns and mechanisms that suitably link planning domains and interrelated knowledge in an ontology are devised. In particular, this enables the use of (standard) ontology reasoning for extending a (hierarchical) planning domain. Furthermore, explanations of plans generated by a cognitive system benefit from additional explanations relying on background knowledge in the ontology and inference. An application of this approach in the domain of fitness training is presented. Alford, Ron, Bercher, Pascal und Aha, David Tight Bounds for HTN planning with Task Insertion Proceedings of the 25th International Joint Conference on Artificial Intelligence (IJCAI 2015) Herausgeber: AAAI Press, 2015 Marker: SFB-TRR-62,Planning Zusammenfassung: Hierarchical Task Network (HTN) planning with Task Insertion (TIHTN planning) is a formalism that hybridizes classical planning with HTN planning by allowing the insertion of operators from outside the method hierarchy. This additional capability has some practical benefits, such as allowing more flexibility for design choices of HTN models: the task hierarchy may be specified only partially, since missing required tasks'' may be inserted during planning rather than prior planning by means of the (predefined) HTN methods. While task insertion in a hierarchical planning setting has already been applied in practice, its theoretical properties have not been studied in detail, yet -- only \EXPSPACE{} membership is known so far. We lower that bound proving \NEXPTIME-completeness and further prove tight complexity bounds along two axes: whether variables are allowed in method and action schemas, and whether methods must be totally ordered. We also introduce a new planning technique called {\em acyclic progression}, which we use to define provably efficient TIHTN planning algorithms. Alford, Ron, Bercher, Pascal und Aha, David Tight bounds for HTN planning with Task Insertion (Extended Abstract) Proceedings of the Eighth Annual Symposium on Combinatorial Search (SoCS) Herausgeber: AAAI Press, 2015 Marker: SFB-TRR-62,Planning Zusammenfassung: Hierarchical Task Network (HTN) planning with task insertion (TIHTN planning) is a variant of HTN planning. In HTN planning, the only means to alter task networks is to decompose compound tasks. In TIHTN planning, tasks may also be inserted directly. In this paper we provide tight complexity bounds for TIHTN planning along two axis: whether variables are allowed and whether methods must be totally ordered. Bercher, Pascal, Höller, Daniel, Behnke, Gregor und Biundo, Susanne User-Centered Planning - A Discussion on Planning in the Presence of Human Users Proc. of the Int. Symposium on Companion Technology (ISCT 2015) 2015 Marker: SFB-TRR-62,Planning Zusammenfassung: AI planning forms a core capability of intelligent systems. It enables goal directed behavior and allows systems to react adequately and flexibly to the current situation. Further, it allows systems to provide advice to a human user on how to reach his or her goals. Though the process of finding a plan is, by itself, a hard computational problem, some new challenges arise when involving a human user into the process. Plans have to be generated in a certain way, so that the user can be included into the plan generation process in case he or she wishes to; the plans should be presented to the user in an adequate way to prevent confusion or even rejection; to improve the trust in the system, it needs to be able to explain its behavior or presented plans. Here, we discuss these challenges and give pointers on how to solve them. Alford, Ron, Bercher, Pascal und Aha, David Tight Bounds for HTN Planning Proceedings of the 25th International Conference on Automated Planning and Scheduling (ICAPS 2015) Herausgeber: AAAI Press, 2015 Marker: SFB-TRR-62,Planning Zusammenfassung: Although HTN planning is in general undecidable, there are many syntactically identifiable sub-classes of HTN problems that can be decided. For these sub-classes, the decision procedures provide upper complexity bounds. Lower bounds were often not investigated in more detail, however. We generalize a propositional HTN formalization to one that is based upon a function-free first-order logic and provide tight upper and lower complexity results along three axes: whether variables are allowed in operator and method schemas, whether the initial task and methods must be totally ordered, and where recursion is allowed (arbitrary recursion, tail-recursion, and acyclic problems). Our findings have practical implications, both for the reuse of classical planning techniques for HTN planning, and for the design of efficient HTN algorithms Bercher, Pascal, Richter, Felix, Hörnle, Thilo, Geier, Thomas, Höller, Daniel, Behnke, Gregor, Nothdurft, Florian, Honold, Frank, Minker, Wolfgang, Weber, Michael und Biundo, Susanne A Planning-based Assistance System for Setting Up a Home Theater Proceedings of the 29th National Conference on Artificial Intelligence (AAAI 2015) , Seite 4264--4265. Herausgeber: AAAI Press, 2015 Marker: SFB-TRR-62,Planning Zusammenfassung: Modern technical devices are often too complex for many users to be able to use them to their full extent. Based on planning technology, we are able to provide advanced user assistance for operating technical devices. We present a system that assists a human user in setting up a complex home theater consisting of several HiFi devices. For a human user, the task is rather challenging due to a large number of different ports of the devices and the variety of available cables. The system supports the user by giving detailed instructions how to assemble the theater. Its performance is based on advanced user-centered planning capabilities including the generation, repair, and explanation of plans.
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# Dissertation

Meine Dissertation beschreibt eigene Beiträge in den Bereichen Hierarchisches Planen und Partial-Order Causal-Link (POCL)-Planen:

• Ich stelle einen vereinfachten, rein propositionalen Formalismus für hierarchisches Planen vor und zeige, dass dieser dieselbe Problemkomplexität ("Existiert eine Lösung für das gegebene hierarchische Problem?") besitzt wie die bisher bekannte Formalisierung (IJCAI 2011).
• Ich untersuche die Problemkomplexität für hierarchisches Planen für den Fall, dass man auch das Einfügen von Aktionen in Pläne zulässt. Es zeigt sich, dass hierdurch das Problem stark vereinfacht wird: Statt semi-entscheidbar ist das Problem dann in EXPSPACE (IJCAI 2011).
• Ich untersuche, wie man hierarchische Planungsprobleme mit Hilfe des POCL-Planens lösen kann. Hierzu habe ich stark an der Entwicklung einer Landmarkentechnik mitgewirkt (AAAI 2012) und diese weiter entwickelt (SoCS 2014), welche das Konzept der Landmarken aus dem nicht-hierarchischen Planen in das hierarchische Planen überträgt.
• Ich untersuche auch, wie man nicht-hierarchische Planungsprobleme mit POCL-Planen löst.

• Auf der theoretischen Seite habe ich dazu untersucht, wie die Problemkomplexität für eine bestimmte Art der Problemrelaxierung aussieht. Die sogenannte Delete-Relaxierung resultiert im zustandsbasierten Planen in eine Problemklasse, die in P entscheidbar ist, während die analoge Problemklasse im POCL-Planen NP-vollständig ist (ICTAI 2013).
• Dieser Beweis resultiert direkt in eine neue Heuristik für POCL-Planen (ICTAI 2013), die qualitativ neue Eigenschaften besitzt im Vergleich zu bisher existierenden POCL-Heuristiken.
• Zusätzlich habe ich eine Technik entwickelt, mit der man Heuristiken aus dem zustandsbasierten Planen direkt im POCL-Planen einsetzen kann (KEPS 2013, KI 2013).

Die folgenden Vorträge beschreiben mein Promotionsvorhaben:

• Vortrag zum Promotionsvorhaben; ca. 2 Jahre vor geplanter Abgabe.

# Betreuungen

Ich habe diverse Bachelor-/Master- und Diplomarbeiten ausgeschrieben sowie einige HiWi-Jobs. Siehe: