Computational power of cell separation in tissue P systems

Polynomially uniform families of tissue P systems with the operation of cell separation were recently studied. Their computational power in polynomial time was shown to range between P and NP∪co-NP, characterizing borderlines between tractability and intractability by the length of rules controlling the interchange of objects. Here, we show that the computational power of these uniform families is limited by the class PSPACE, which is the class characterizing the power of classical parallel computing models, such as PRAM or the alternating Turing machine.