Markov Algorithm

"A Markov algorithm is a string rewriting system that uses grammar-like rules to operate on strings of symbols. Markov algorithms have been shown to have sufficient power to be a general model of computation, and can thus be shown to be equivalent in power to a Turing machine. Since this model is Turing-complete, Markov algorithms can represent any mathematical expression from its simple notation."

http://en.wikipedia.org/wiki/Markov_algorithm