Introduction: Membrane Computing — What It Is and What It Is Not

The history of formalizing the notion of algorithm (and of computation) dates back to G.W. Leibniz (1646–1716) when it focused on trying to model the computations performed by humans, for example bank clerks. These efforts culminated in the first part of the 20th century with the formalization in the form of machines, in the work of Turing [238]. These formalizations were very successful, because they led to the construction of the first electronic computers in the 1940’s. These efforts already were using some ideas from biology, for example, the functioning of neurons in neural networks (Kleene [106], McCulloch and Pitts [165]).