Frisco, Pierluigi2016-02-232016-02-23200484-688-6101-4http://hdl.handle.net/11441/36314It is proved that four membranes su±ce to P systems with minimal symport/antiport to generate all recursively enumerable sets of numbers. It is also proved that P systems with symport/antiport without maximal par- allelism are equivalent to partially blind counter automata.application/pdfengAttribution-NonCommercial-NoDerivatives 4.0 Internacionalhttp://creativecommons.org/licenses/by-nc-nd/4.0/info:eu-repo/semantics/conferenceObjectinfo:eu-repo/semantics/openAccess