. . "We resume computational complexity aspects of several models of membrane systems, namely P systems with active membranes, P systems with proteins on membranes and tissue P systems both with membrane separation and membrane division. A sequence of common issues is studied in relation to these P system models, and 16 open problems are stated in the text. We question the role of families of P systems and their necessity to solve computationally hard problems in polynomial time. For each P system model we focus on conditions guaranteeing the polynomial equivalence of families of P systems and Turing machines. The ability of P systems to solve NP/co-NP-complete problems in polynomial time (trading space for time) is a very popular issue. Interesting characterizations of the borderline between tractability and intractability, i.e., P/NP, have been recently shown. Similarly important, although less popular, is the relation between NP/co-NP and further classes as PP, the polynomial hierarchy PH and PSPACE. Several models of P systems has been shown to characterize the class PSPACE which itself characterizes parallel computations with an unlimited number of processors but a limited propagation of data between them." . "Membrane computing; active membrane; tissue P system; complexity"@en . "Berlin" . "15"^^ . "RIV/47813059:19240/14:#0005320" . . "Membrane Computing - 14th International Conference" . "Moldavsk\u00E1 republika" . "1"^^ . "P(ED1.1.00/02.0070)" . . "[86629C087332]" . "1"^^ . . . "0302-9743" . . . . . . "Active Membranes, Proteins on Membranes, Tissue P Systems: Complexity-Related Issues and Challenges"@en . . "RIV/47813059:19240/14:#0005320!RIV15-MSM-19240___" . "Springer-Verlag" . . "Active Membranes, Proteins on Membranes, Tissue P Systems: Complexity-Related Issues and Challenges"@en . "Active Membranes, Proteins on Membranes, Tissue P Systems: Complexity-Related Issues and Challenges" . "We resume computational complexity aspects of several models of membrane systems, namely P systems with active membranes, P systems with proteins on membranes and tissue P systems both with membrane separation and membrane division. A sequence of common issues is studied in relation to these P system models, and 16 open problems are stated in the text. We question the role of families of P systems and their necessity to solve computationally hard problems in polynomial time. For each P system model we focus on conditions guaranteeing the polynomial equivalence of families of P systems and Turing machines. The ability of P systems to solve NP/co-NP-complete problems in polynomial time (trading space for time) is a very popular issue. Interesting characterizations of the borderline between tractability and intractability, i.e., P/NP, have been recently shown. Similarly important, although less popular, is the relation between NP/co-NP and further classes as PP, the polynomial hierarchy PH and PSPACE. Several models of P systems has been shown to characterize the class PSPACE which itself characterizes parallel computations with an unlimited number of processors but a limited propagation of data between them."@en . . "19240" . "2013-01-01+01:00"^^ . "Sos\u00EDk, Petr" . "Active Membranes, Proteins on Membranes, Tissue P Systems: Complexity-Related Issues and Challenges" . "978-3-642-54238-1" . "1524" . . . .