Membrane Computing

This volume is based on papers presented at the5thWorkshoponM- brane Computing, WMC5, which took place in Milan, Italy, in the period June 14-16, 2004, as a satellite event of DNA10 (10th International Workshop on DNA-Based Computing). The ?rst three workshops were organized in Curtea de Arge¿ s, Romania - they took place in August 2000 (with the proceedings p- lished in Lecture Notes in Computer Science, volume 2235), in August 2001 (with a selection of papers published as a special issue ofFundamenta Inform- icae, volume 49, numbers 1-3, 2002), and in August 2002 (with the proceedings publishedinLectureNotesinComputerScience,volume2597).Thefourthwo- shop took place in Tarragona, Spain, in July 2003 (the proceedings appeared as volume 2933 of Lecture Notes in Computer Science). Like the previous two meetings, also WMC5 was an o?cial workshop of the Molecular Computing Network (MolCoNet) funded by the EU Commission in theFifthFrameworkprogramInformationSocietyTechnologies(projectnumber IST-2001-32008). The preproceedings of WMC5 were published as a MolCoNet report, and they were available during the workshop. This volume contains only a selection of the papers from the preproceedings.