General Information Many forms of contributions to the challenge are conceivable. Participants may wish to implement algorithms or use existing implementations for evaluation; participants may develop new algorithms, implement them and compare to existing ones; participants may formalize the underlying biological problem in a new manner and subsequently show the merits of the resulting algorithms and implementation over existing ones. However, in any case an emphasis should be placed on validation of results on real and artificial data sets. The introductory text on fragment assembly contains references to data sets and for genome rearrangements the data sets are currently being put together. Prospective participants in the implementation challenge are asked to contact the program committee and submit abstracts of their project. The abstract is meant to be informal. Send e-mail to vingron@gmd.de . The committee offers the participants advice and support in their projects throughout the duration of the implementation challenge. DIMACS facilities will provide a clearing-house for exchange of programs and data and for communication among researchers. Any questions and comments on the challenge and/or the documents here are welcome and may also be directed to vingron@gmd.de .