September 22 – 27 , 2013, Dagstuhl Seminar 13391

Algorithm Engineering


Andrew V. Goldberg (Microsoft Corp. – Mountain View, US)
Giuseppe F. Italiano (University of Rome "Tor Vergata", IT)
David S. Johnson (New York, US)
Dorothea Wagner (KIT – Karlsruher Institut für Technologie, DE)

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Dagstuhl Report, Volume 3, Issue 9 Dagstuhl Report
Aims & Scope
List of Participants
Dagstuhl Seminar Schedule [pdf]


Topics of the Seminar

The seminar covered all methodological aspects of algorithm engineering. Examples are the scientific method in algorithmics, the use of modern computer architecture in algorithmics, and certifying algorithms. These aspects were also addressed in dedicated discussion sessions.

Science of Algorithms

One aspect of algorithm engineering is the scientific method, where research on algorithms is interpreted as in other disciplines such as physics and life sciences: the observation of a phenomenon that is not yet understood is investigated via falsifiable hypotheses as explanations of the phenomena, and experimental evaluations to test these hypotheses. That way not only empirical evidence on the behavior of algorithms is attained but also new theoretical insights are sought. Experimental algorithmics is already a core component of algorithm engineering from its very beginning. However, the design of reasonable experiments, the use of meaningful test instances, and reproducibility of experiments are still issues to be discussed in order to derive a common understanding and agree on a best practice.

Manycore and GPU Algorithms

Exploiting the full potential of a modern computer poses many interesting new challenges for algorithm engineering: ever increasing parallelism, deep memory hierarchies, and heterogeneous architectures. Algorithms should be tailored to utilize multiple cores, but also access memory efficiently, taking into account issues such as data locality. Nowadays the use of GPUs, which are increasingly common in modern servers, is an important issue for efficient algorithm implementation. This is in particular interesting for frequently used and "classical" algorithms.

Certifying Algorithms

An effective way to ensure correct results of algorithm implementations are certifying algorithms. The idea is to check each returned result for correctness using a simple checker. It then suffices to test or perhaps verify the checker. Making checking fast implies interesting algorithmic questions when checking is aided by certificates of correctness computed by the main algorithm.

Focus Topic: Web Search and Large Graphs

Experiences from previous Dagstuhl seminars showed that the interaction between different scientific communities stimulates methodological discussions. This exchange is in particular important for neighboring scientific communities who typically meet at separate conferences. For this seminar, we focus on web search, large graphs and social networks in order to also address the scientific WWW and Social Media community. In these fields, methods from algorithm engineering are applied. However, these scientists typically don't publish at the algorithm engineering conferences mentioned above but meet and publish at conferences like the "International World Wide Web Conference", the "ACM Conference on Hypertext and Hypermedia" or the "International AAAI Conference on Weblogs and Social Media".

Search engines work with a large amount of data, making high-performance algorithms and data structures very important. Relevant problems include fast indexing, text and query processing, and relevance computation. The latter involves a large web graph. Web-enabled applications give raise to other large graphs, such as social networks, like "friend graphs" or e-mail graphs induced by message origin-destination pairs. Algorithms on such graphs are of great interest. For example, identifying interest-based sub-communities (e.g., classical music fans) enables better service experience or contextual advertisement.


The aim of this seminar was to bring together researchers with different backgrounds, e.g., from algorithm and datastructures, computational geometry, combinatorial optimization, parallel algorithms and algorithm engineering in order to strengthen and foster collaborations and to identify key research directions for the future. In particular, the seminar was intended to foster the exchange between algorithm engineering and scientists from the web search community. While the dominant goal of the seminar was the exchange of current research developments and discussion of topical subjects, it also contributed to bring algorithm engineering forward as a still evolving and expanding field in computer science. The seminar program included four dedicated discussion sessions on methodological questions, as well as research related issues like future DIMACS Implementation Challenges.


The organizers decided to schedule talks and discussions not grouped according to topics but provide a vivid mix of different research questions and results. According to the composition of the seminar participants, not all topics were covered equally well. For example, certifying algorithms were not addressed in detail. On Monday, Renato Werneck gave a short report on the "11th DIMACS Implementation Challenge on Steiner Tree Problems" taking place in 2013/14. The program of Monday afternoon was concluded by a panel discussion on "Empirical and Theoretical Approaches to Algorithm Design: Synergies and Opportunities". The second panel discussion on "Benchmarks and reproducibility of experiments" took place on Tuesday. The third panel discussion on Thursday focused on "Promoting and advancing the field" and on Friday a discussion about "Teaching Algorithm Engineering" concluded the program.

The seminar hosted 39 participants. Besides presentations and panel discussions the program offered room for bilateral discussions and working groups. Schloss Dagstuhl and its staff provided a very convenient and stimulating environment. The seminar participants appreciated the cordial atmosphere which improved mutual understanding and inspiration. The organizers of this seminar wish to thank all those who helped make the workshop a fruitful research experience.

Summary text license
  Creative Commons BY 3.0 Unported license
  Andrew V. Goldberg, Giuseppe F. Italiano, David S. Johnson, and Dorothea Wagner

Related Dagstuhl Seminar


  • Data Bases / Information Retrieval
  • Data Structures / Algorithms / Complexity
  • World Wide Web / Internet


  • Experimental algorithmics
  • Parallel and distributed computing
  • Web search
  • Social networks


In the series Dagstuhl Reports each Dagstuhl Seminar and Dagstuhl Perspectives Workshop is documented. The seminar organizers, in cooperation with the collector, prepare a report that includes contributions from the participants' talks together with a summary of the seminar.


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Dagstuhl's Impact

Please inform us when a publication was published as a result from your seminar. These publications are listed in the category Dagstuhl's Impact and are presented on a special shelf on the ground floor of the library.


Furthermore, a comprehensive peer-reviewed collection of research papers can be published in the series Dagstuhl Follow-Ups.