# Nonuniversality in computation: A proof by semantic shift?

Today, the 8th of September 2016, we had a very interesting discussion about a theorem, due to Selim G. Akl, pointed to me in a tweet by Andy Adamatzky. Such theorem has, according to Akl, the consequence that the Church-Turing thesis, a basic tenet of theoretical computer science, is false. Of course, surprising statements require solid arguments: is Akl’s solid enough?

First of all, let us recall what the Church-Turing thesis is, and what it is not. Its statement, as reported by the Stanford Encyclopedia of Philosophy, goes as follows: Continue reading