Foundations of Artificial Intelligence (FAI) Group
Prof. Dr. Joerg Hoffmann
Foundations of Artificial Intelligence Group
Campus E1 1
66123 Saarbruecken, Germany
Consultation hour (Sprechstunde) Tuesdays, 14:00--15:00.
+49 (0) 681 302 71471
+49 (0) 681 302 57342
Research Interests. I'm interested in a range of topics
involving issues such as hard search problems, practical problem
distributions, data structures and efficient implementation, modeling,
and validation. My main field of expertise is Automatic Planning
(commonly also referred to as AI Planning), on which I have worked
since 1997. Since ca. 2003, I have also worked on topics from SAT/CP
and from model checking. Since 2006, I've been doing research on
semantic technologies, including automated composition of web
services, modeling and discovery of geospatial web services, and
business process management. Most recently I've taken up research on
markov decision processes, as well as application-driven research in
network security testing.
Short CV. I received a diploma in computer science from
University Freiburg, Germany, in March 1999, and completed my PhD at
the same University in July 2002, with a thesis that won
Dissertation award 2002. I stayed on as a Postdoc until August
2004. From September 2004 until April 2006, I was a Researcher at Max
Planck Institute for Computer Science, Saarbruecken, Germany. From
April 2006 through August 2006, I was a Visiting Scientist at Cornell
University, Ithaca, NY, USA. From September 2006 until April 2008, I
was a Senior Researcher at the University of Innsbruck (Austria),
where I submitted/obtained my Habilitation in March 2008/April
2009. From April 2008 until September 2009, I was a Senior Researcher
at SAP Research, Karlsruhe, Germany. From October 2009 until March
2012, I was a Directeur de Recherche at INRIA, Nancy, France, enjoying
French life style and partly also enjoying the French language :-) I
finally became a Professor at Saarland University in April 2012, where
I'm heading the Foundations of Artificial
A central activity in my research area is the development of systems,
whose empirical performance serves to evaluate the underlying
ideas. Here 's a list of systems I've been involved in:
- IPP. This
is a planning tool I implemented as a student. It is based on the
Graphplan algorithm and nowadays largely outdated.
- FF. This planning tool was started in my
PhD thesis, and gained fame by outclassing the competition in the 2000
International Planning Competition (IPC), setting a completely new
standard in planner performance. The tool is still widely used today;
variants of its key techniques are used in almost every state of the
art planner. FF has been extended to several expressive variants of
planning, implemented in the tools Metric-FF (numeric state
variables), Conformant-FF (uncertain initial states), Contingent-FF
(partial observability), and Probabilistic-FF (like Conformant-FF but
with probabilistic initial states and action effects).
- SATPLAN. This
planner, originally proposed by Henry Kautz and Bart Selman, compiles
planning into a series of SAT problems. It has long dominated the
track for optimal planning tools at the IPC. My contribution amounted
to implementation works on encoding planning into SAT.
- UPPAAL. This is a very
widely used tool for model checking networks of timed automata. With
co-workers at the Ujniversity of Freiburg, I adapted planning
heuristic functions to this context, and showed that they can be
useful to more effectively find bugs (paths to undesired states) in
the state spaces of such networks.
- TorchLight is a recent tool I
have developed, which allows to analyze search space topology without
actually running any search. The tool applies to planners based on the
"ignoring delete lists" relaxation.
- adl2strips translates input from the
ADL planning language, which allows arbitrary first-order formulas in
operator preconditions and the goal, to the simpler STRIPS language
which restricts these to conjunctions of atoms. The tool also features
two methods for compiling away conditional effects. It has been used
in the 2004 IPC, and in some later editions of the IPC as well.
Downward. This planning tool was started in the PhD thesis of
Malte Helmert, and has in the meantime evolved into the main platform
for implementing and evaluating planning algorithms. Fast Downward
implements a great variety of search techniques based on heuristic
search (including those of FF). The FAI group are regular
contributors, devising for example some of the techniques
-- merge-and-shrink abstractions, a method to compute lower
bound heuristic functions to be used for optimal planning -- that were
awarded in the 2011 IPC versions of Fast Downward.
Attention lecturers! All lecture slide sources are
available on request. Just email me.
- Winter term 13/14, Saarland University:
- Winter term 13/14, Saarland
University: Planning and
- Summer term 13, Saarland
- Winter term 12/13, Saarland University:
- Winter term 12/13, Saarland
Search Algorithms (Seminar).
- Summer term 12, Saarland University:
- Winter term 07/08, University of Innsbruck: Automatic Planning
- Winter term 05/06, Saarland University: Automatic Planning
- Summer term 05, Saarland University: Automatic Planning Systems
- Winter term 04/05, Saarland University: Search Methods for
Transition Systems, Example AI Planning (Lecture).
2013 Best PC Member Award.
2013 Influential Paper Award (with Julie Porteous and Laura
2012 Best Paper Award (with Emil Keyder and Patrik Haslum).
of the optimal track at the 7th International Planning Competition
(IPC'11), with Fast Downward Stone-Soup (1st prize) and
Merge-and-Shrink (2nd prize).
- Nominated for ICAPS 2011 Best Paper Award.
2008 Influential Paper Award, Honorable Mention (with Jana
Koehler, Bernhard Nebel, and Yannis Dimopoulos).
2007 Best Research Paper Award (with Malte Helmert and Patrik
- Nominated for IJCAI 2007 Best Paper Award (with Carla Gomes,
Ashish Sabharwal, and Bart Selman).
of the optimal track at the 5th International Planning Competition
(IPC'06), with SATPLAN.
- Nominated for ICAPS 2006 Best Paper Award (with Ashish Sabharwal
and Carmel Domshlak).
- IJCAII-JAIR Best
Paper Prize 2005 (with Bernhard Nebel).
- AAAI 2005 Outstanding PC Member Award.
2004 Best Paper Qward (with Ronen Brafman).
Dissertation Award 2002. Award for the best European Dissertation
in the field of AI. Awarded annually by ECCAI, the European
Coordination Committee for Artificial Intelligence.
- Winner of the
fully-automated track at the 2nd International Planning Competition
(IPC'00), with FF.
of the ADL track at the 1st International Planning Competition
(IPC'98), with IPP.
- Program Co-Chair of
National Conference of the American Association for Artificial
- Member of the Executive Council of
Conference on Automated Planning and Scheduling (ICAPS).
- Associate Editor
(Journal of Artificial Intelligence Research).
- Area Chair for Planning
of AI Communications, the
European Journal on AI [2009--2012].
- Conference Co-Chair of
International Conference on Automated Planning and Scheduling
- Invited Speaker at the 34th Annual
German Conference on Artificial Intelligence.
- Lecturer at the Summer School on Automated Planning and
- Lecturer at
Summer School on Automated Planning and Scheduling 2011.
- Lecturer at the International Summer
School on AI Planning 2003.
- Technical Coordinator of EU-funded STREP SWING: Semantic Web
Service Interoperability for Geospatial Decision Making.
- Sponsorship Co-Chair of ICAPS 2014.
- Demonstrations Chair of ESWC 2008.
- Doctoral Consortium Co-Chair of ICAPS 2007.
- Tutorial Chair of KI 2007.
- Founding member of the permanent IPC committee established by the
ICAPS council at ICAPS 2006.
- Member of the organizing committee of the International Planning
- Invited speaker at the Workshop on Local Search Techniques in
Constraint Satisfaction at CP 2005.
- Co-Chair of the International
Planning Competition 2004.
- Member of the Senior Program Committees of AAAI'15, ECAI'14,
ICAPS'14, IJCAI'13, AAAI'11, ICAPS'11, IJCAI'11, AAAI'10, ICAPS'09,
IJCAI'09, AAAI'08, and AAAI'07.
- Member of the Program Committees of AAAI'14, WIMS'14, AAAI'13,
SOCS'13, ICAPS'13, KR'12, SOCS'11, KI'11, CPAIOR'09, AIMSA'08,
ECAI'08, ICAPS'08, ICAPS'07, KI'07, SPIN'07, ECAI'06, AAAI'06,
ICAPS'06, IJCAI'05, AAAI'05, ICAPS'05, ICAPS'04, AI&Math'04, ICAPS'03,
- Co-Chair of the 3rd Workshop on Heuristics for
Domain-Independent Planning (HDIP'11) at ICAPS 2011.
- Co-Chair of the 2nd Workshop on Heuristics for
Domain-Independent Planning (HDIP'09) at ICAPS 2009.
- Co-Chair of the workshop Semantic Web meets Geospatial
Applications at AGILE 2008.
- Co-Chair of the workshop Heuristics for Domain-Independent
Planning: Progress, Ideas, Limitations, Challenges at ICAPS
- Co-Chair of the workshop
on the competition at ICAPS 2003.
Ah yes, I also have hobbies.
Here's the glorious web page of my
Inglorious Mustard Boys ...