Parallel Problem Solving from Nature
Parallel Problem Solving from Nature is a peer-reviewed research conference focusing on the topic of natural computing. As such it includes a wide scope of computer science. It originated in 1990 and has been held biennially across European locations ever since. Papers selected for PPSN conferences are presented as posters and published in proceedings in the Springer Lecture Notes in Computer Science series. PPSN conferences also include presentations by keynote speakers representing diverse viewpoints in the field, [|tutorials] given by experts, and [|workshops] for discussion of topics that may not be fully represented in the main conference. These activities that should advance the field of natural computing probably explain why PPSN gained an A-ranking in the 2023 CORE computer science conference ranking system, reflecting its importance as a venue in which computer science researchers can participate.
Origin
The idea behind PPSN emerged around 1989-1990 when Bernard Manderick, Reinhard Männer, Heinz Mühlenbein, and Hans-Paul Schwefel, realised they shared a common field of study that was not covered by the conferences on Operations Research, Physics, or Computer Science they attended regularly.The field of genetic algorithms had already been established in the form of the ICGA conference in 1985, but the founders of PPSN wanted a wider focus, with algorithms that included problem solving, parallel computing and the use of natural metaphors.
The success of the first PPSN event at Dortmund encouraged its organisers to start a biennial conference series, as a European counterpart to the American-based ICGA.
Analogies to natural processes included the thermodynamic process of annealing, immune systems and neural networks, as well as other paradigms, with Darwinian evolution being by far the most frequently used metaphor.
In this way, evolutionary algorithms and evolutionary computation became the common denominator for the PPSN approach to problem solving by mimicking biological principles like populations, birth, death, mutation, recombination, and natural selection.
History
So far, eighteen PPSN conferences have been held. The table below describes their dates, locations and cites their websites and proceedings, where accessible. The importance of Dortmund, as the location of the Technical University of Dortmund, where the conference originated, as the location of many successor conferences and as the location of on-going relevant research, should not be understated.| Year | Dates | Location | Website | Proceedings |
| 1990 | 1–3 October | Dortmund | No | LNCS 496 |
| 1992 | 28–30 September | Brussels | No | PPSN II |
| 1994 | 9–14 October | Jerusalem | No | LNCS 866 |
| 1996 | 22–26 September | Berlin | No | LNCS 1141 |
| 1998 | 27–30 September | Amsterdam | No | LNCS 1498 |
| 2000 | 16–20 September | Paris | No | LNCS 1917 |
| 2002 | 7–11 September | Granada | No | LNCS 2439 |
| 2004 | 18–22 September | Birmingham | No | LNCS 3242 |
| 2006 | 9–13 September | Reykyavik | No | LNCS 4193 |
| 2008 | 13–17 September | Dortmund | Yes | LNCS 5199 |
| 2010 | 11–15 September | Krakow | Yes | LNCS 6238, LNCS 6239 |
| 2012 | 1–5 September | Taormina | No | LNCS 7491, LNCS 7492 |
| 2014 | 13–17 September | Ljubljana | No | LNCS 8672 |
| 2016 | 17–21 September | Edinburgh | Yes | LNCS 9921 |
| 2018 | 8–12 September | Coimbra | No | LNCS 11101, LNCS 11102 |
| 2020 | 5–9 September | Leiden | No | LNCS 12269, LNCS 12270 |
| 2022 | 10–14 September | Dortmund | No | LNCS 13398, LNCS 13399 |
| 2024 | 14–18 September | Hagenberg | Yes | LNCS 15148, LNCS 15149, LNCS 15150, LNCS 15151 |
| 2026 | 29 August-2 September | Trento | Yes | Pending |
Organisation
Each PPSN conference as any peer-reviewed research conference requires a substantial amount of organisation. The organisers are people from the research community covered by the conference. Due to the long history of the conference it is not possible to present all organisers of all conferences. For some recent conferences the organisers can be identified from the conference website. For other recent conferences where the website is no longer available the conference organisers are listed in the Table of Contents Front Matter of the Conference Proceedings. In the table below the main organisers of the most recent PPSN conferences are given. The sources of the information about organisation are cited adjacent to each year.Hans-Paul Schwefel, recognised for his founding role in PPSN conferences, has been Honorary Chair of the PPSN conferences from 2020 to 2024 listed below. It may be assumed that he will continue in that position during the forthcoming PPSN 2026, but that has not yet been confirmed. When PPSN was held in Leiden in 2020 Grzegorz Rozenberg was also an Honorary Chair.
In addition to the organisers listed in the table below, there are others, whom may not always be recognised in each conference proceedings, or through the same title. Local Chairs or Local Support Chairs are very important to make sure that the conference takes place smoothly in the agreed venue. Some conferences have listed Technical Support Chairs or Online Conference Chairs. This will be important to ensure that the equipment in the venue works as expected. This may also have had particular importance in 2020 due the impact of the COVID-19 pandemic, requiring the conference to take place entirely online.
Other organisers were not identified consistently across the three conferences that have completed below, nor in the one forthcoming. This does not imply that they were less important than those included in the table. These included a Keynote Chair, a Competition Chair, an Industrial Liaison Chair and a Social Media Chair.
Not included in the table because of the very large number of people involved are the Programme Committee. Reporting to the Programme Committee Chairs, these are the people who carry out the peer-review process to ensure that PPSN conferences maintain a high standard of academic rigour. A full list of Programme Committee members can be found in the Table of Contents Front Matter of the PPSN conference proceedings following the list of conference organisers given in the Organization section.
| Year | 2020 | 2022 | 2024 | 2026 |
| Location | Leiden | Dortmund | Hagenberg | Trento |
| General Chairs | Thomas Bäck and Mike Preuss | Günter Rudolph | Michael Affenzeller and Stephan Winkler | Giovanni Iacca |
| Programme Committee Chairs | Carola Doerr, Michael Emmerich and Heike Trautmann | Hernán Aguirre, Pascal Kerschke, Gabriela Ochoa and Tea Tušar | Heike Trautmann, Tea Tušar, Penousal Machado and Thomas Bäck | Doina Bucur, Antonio Della Cioppa, Ting Hu and Eric Medvet |
| Proceedings Chairs | André Deutz and Hao Wang | Anna V Kononova | Anna V Kononova | Giorgia Nadizar and Anil Yaman |
| Workshops Chair | Anna Esparcia-Alcázar | Christian Grimm | Roman Kalkreuth | Sarah L. Thomson |
| Tutorials Chair | Ofer Shir | Heike Trautmann | Fabrício Olivetti de França | Yuri Lavinas |
| Publicity Chairs | Bas van Stein and Wenjian Luo | Nicolas Fischöder and Peter Svoboda | Jan Zenisek, Christian Haider and Louise Buur | Jessica Mégane and Jéssica Parente |
Format
Each Parallel Problem Solving from Nature conference includes a variety of activities to update and inform participants about the latest trends in natural computing. Since each conference is biennial a lot may have changed since the last one. Keynote speakers are invited to each conference to give expert lectures on particular topics in the field. Peer-reviewed papers are presented as posters to give a very broad view of the subjects covered by the conference. Time is available for workshops to allow discussion of topics that may not be included in the main conference. In order to enable participants to learn about some topics included in the very broad range of topics that PPSN covers, time is also allowed for tutorials.[|Keynote speakers]
The diversity of subjects that the conference covers means that it has attracted a wide range of keynote speakers in natural computing and related areas. Keynote speakers are listed on PPSN conference websites, or if the website is not available, in the Table of Contents Front Matter of the Conference Proceedings..| Year | Keynote speakers |
| 1998 | Grzegorz Rozenberg, Nicholas Gessler, and Lawrence Davis |
| 2000 | Aaron Sloman, Luc Steels and Henrik Hautop Lund |
| 2002 | Alexander Nareyek, Roderic Guigó and William Hart |
| 2004 | Mandyam V. Srinivasan, Benjamin W. Wah and C. Lee Giles |
| 2006 | Herschel Rabitz, Nadia Busi, and Edward Tsang |
| 2008 | Levent Tunçel, Thomas Breitling and Arndt von Haeseler |
| 2010 | Jon Garibaldi, Zbigniew Michalewicz and Darrell Whitley |
| 2012 | Angelo Cangelosi, Natalio Krasnogor, Panos M. Pardalos, and Leslie G. Valiant |
| 2014 | Jadran Lenarčič, Thomas Bäck and A. E. Eiben |
| 2016 | Susan Stepney, Josh Bongard and Andrew Philippides |
| 2018 | Ahmed Elgammal, Francis Heylighen and Kurt Mehlhorn |
| 2020 | Eric Postma, Carme Torras and Christian Stöcker |
| 2022 | Doina Bucar, Claudio Semini and Travis Waller |
| 2024 | Oliver Schütze, Richard Küng and Bernardino Romera-Paredes |
Papers
Similar to many other research conferences, PPSN invites the submission of [|papers]. These are peer-reviewed and the ones selected for publication will be published in the conference proceedings published in the Springer Lecture Notes in Computer Science series, cited for past conferences in the table above, given in the history section. A possibly unique feature of PPSN conferences is that accepted papers are not oral presentations in the conference, they are presented in a poster session. This allows more papers to be included, as well as allowing attendees to gain more information beyond the poster when the conference proceedings are published.Workshops
Each PPSN conference includes workshops, these are intended as "forums for presenting and discussing new emerging approaches or for critical reflections within a subfield. They provide an excellent opportunity to meet people with similar interests, to be exposed to cutting-edge research and to exchange ideas in an informal setting". They typically take place over one day or half a day, although some may be smaller. A call for workshop proposals is published by the conference organisers well in advance so that accepted workshop organisers can manage their workshop independently of the main conference programme, other than with the knowledge of the time slot within which their workshop will fit. PPSN 2024 included four workshops described in the table below.| Number | Organisers | Title |
| 1 | Tinkle Chugh, George De Ath, Paul Kent, Alma Rahat and Kaifeng Yang | BOSS: Bayesian and Surrogate-assisted Search and Optimisation |
| 2 | Carola Doerr, Vanessa Volz, Boris Naujoks, Olaf Mersmann, Mike Preuss and Pascal Kerschke | Good Benchmarking Practices for Evolutionary Computation BENCHMARKING |
| 3 | Benjamin Doerr, Concha Bielza, John McCall and Weijie Zheng | 30 Years of EDAs |
| 4 | Heike Trautmann, Lennart Schapermeier and Oliver Schütze | Multimodal Multiobjective Optimization |
Tutorials
PPSN conferences include tutorial sessions where experts in particular areas of the fields covered by the conference present in order to enable participants to learn about topics they may have been unfamiliar with before the conference. Unlike workshops, which may be regarded as mini-conferences and involve multiple presenters, tutorials at PPSN conferences are organised as detailed lectures, usually with only one or a few presenters. Thus there is time to include more tutorials than workshops in each PPSN conference. The table below provides information about the tutorials presented at the PPSN 2024 conference, the times and dates of which are shown in the PPSN 2024 Program. Titles are shown as given in the 2024 program.| Number | Presenter | Title |
| 1 | Ke Li | Decomposition Evolutionary Multi-Objective Optimization: What We Know from the Literature and What We are not Clear from a Data Science Perspective |
| 2 | Benjamin Doerr | A Gentle Introduction to Theory |
| 3 | Nikolaus Hansen | CMA-ES |
| 4 | Ofer M Shir | Mathematical Programming as a Complement to Bio-inspired Optimization |
| 5 | Martin Krejca | Theory of Estimation of Distribution Algorithms |
| 6 | Michal Pluhacek, Adam Vikorin and Roman Senkerik | Large Language Models as Tools for Metaheuristic Design: Exploring Challenges and Opportunities |
| 7 | Bogodan Fipič and Aljosa Vodopija | Constraint Handling in Multiobjective Optimization |
| 8 | Kate Smith-Miles and Mario Andrés Muñoz Acosta | Instance Space Analysis for Rigorous and Insightful Algorithm Testing |
| 9 | Chao Qian | Pareto Optimization for Subset Selection: Theories and Practical Algorithms |
| 10 | Jeroen Rook, Manuel López-Ibáñez and Heike Trautmann | Advanced Use of Automatic Algorithm Configuration: Single- and Multi-Objective Approaches |
| 11 | Michael Hellwig, Steffan Fink and Hans-Georg Beyer | Introduction to Evolution Strategies for Constrained Optimization Problems |
| 12 | Per Kristian Lehre | Runtime Analysis of Population-based Evolutionary Algorithms |
| 13 | Anna V Kononova, Niki van Stein and Diederick Vermetten | Structural bias in optimsation algorithms |
| 14 | Nelishia Pillay | Transfer Learning in Evolutionary Spaces |
| 15 | Per Kristian Lehre and Mario A Hevia Fajardo | Adversarial Optimisation through Competitive Coevolutionary Algorithms |
| 16 | A E Eiben | Robot Evolution |
Importance
Parallel Problem Solving from Nature conferences have become an established feature of European natural computing and evolutionary computation research, over the 35 years that they have been held. They have been held over a longer period than the other biennial European conference in related fields, Artificial Evolution, which has recently also been held in even-numbered years, but not on conflicting dates. In earlier years the Artificial Evolution conference was held in odd-numbered years, thus preventing any risk of conflict. Because Artificial Evolution conferences have usually been held in locations in France, PPSN has offered a wider range of locations.Although they are not annual, they have complemented the annual European EvoStar conferences, the latter being focused through sub-conferences on four areas arguably narrower in total than the scope of PPSN.
PPSN conferences do not include the very large number of simultaneous tracks that much larger global conferences in evolutionary computation and related fields, such as GECCO or IEEE CEC can do. So PPSN conferences cannot attract a similar number of attendees to each conference as these conferences. However, being smaller and located in venues typically easier to reach across Europe, they enable interaction between participants to be easier. Through peer-review they maintain a high standard of publication from each conference. Via keynote speakers, tutorials and workshops they help advance the fields included within the scope of the conference.
It is thus not surprising that Parallel Problem Solving from Nature gained an A-ranking in the 2023 CORE conference rankings. GECCO and FOGA were two other conferences in the field that also gained A-rankings, but there were many others that gained lower ranks, if at all, supporting the importance of PPSN.
A new round of ICORE ranking is being prepared in 2025, but it is not due to be released until 2026.