Computing by only observing

The paradigm of evolution/observation is based on the idea that a computing device can be obtained by combining a basic system and an observer that transforms the evolution of the basic system into a readable output. In this framework we investigate what can be computed by changing the observer but not the basic observed system. We consider grammars as basic systems combined with finite state automata as observers, watching either the sequence of sentential forms or the productions used by the grammar. It is possible to obtain computational completeness only varying the observer, without modifying the basic system, which is a fixed context-free grammar. © Springer-Verlag Berlin Heidelberg 2006.