Computing Using Signals: From Cells to P Systems

Abstract

In cell biology one of the fundamental topic is the study of how biological signals are managed by cells. Signals can arise from inside the cell or from the external environment and the correct answer to certain signals is essential for bacteria to survive in a certain environment. Starting from these biological motivations we consider a model of P systems where the computa- tion is controlled by signals which move across the regions. In particular, we consider Signals-Based P systems where the symbol-objects cannot be moved and the rules can be activated/inactivated using a ¯nite number of signals (signal-promoters) moved across the membranes; di®erently from standard P systems using promoters, in our case promoters cannot be created during the computation. After discussing the biological motivations we show how this model becomes universal when it uses one catalyst, and a bounded number of signal-promoters.