P systems with active membranes working in sublinear space

P systems with active membranes are a variant of P systems where the membranes can be created during the computation by division of existing ones. Using this feature, one can create an exponential number of membranes in a polynomial time, and use them in parallel to solve computationally hard problems, such as problems in NP or even in PSPACE. This possibility raises many interesting questions concerning the trade–off between time and space needed to solve various classes of computational problems by means of membrane systems. In this paper we concentrate on P systems with active membranes working in sublinear space, with a survey on recent research results concerning such systems