2016-03-302016-03-3020109788461423576http://hdl.handle.net/11441/39139Two proofs have been shown for P systems with active membranes in previ- ously published papers, demonstrating that these P systems can solve in polynomial time exactly the class of problems PSPACE. Consequently, these P systems are equivalent (up to a polynomial time reduction) to Second Machine Class models as the alternating Turing machine or the PRAM computer. These proofs were based on a modified definition of uniform families of P systems. Here we demonstrate that the results remain valid also in the case of standard definitions.application/pdfengAttribution-NonCommercial-NoDerivatives 4.0 Internacionalhttp://creativecommons.org/licenses/by-nc-nd/4.0/info:eu-repo/semantics/conferenceObjectinfo:eu-repo/semantics/openAccesshttps://idus.us.es/xmlui/handle/11441/39139