Le 17-juin-05, à 07:19, Russell Standish a écrit :

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Hmm - this is really a definition of a universal machine. That such a machine exists is a theorem. Neither depend on the Church-Turing thesis, which says that any "effective" computation can be done using a Turing machine (or recursive function, or equivalent). Of course the latter statement can be considered a definition, or a formalisation, of the term "effective computation.

`Hmm - I disagree. Once you give a definition of what a turing machine`

`is, or of what a program fortran is, then it is a theorem that`

`universal turing machine exists and that universal fortran program`

`exists. To say that a universal machine exists, computing by definition`

`*all* computable function, without any "turing" or "fortran"`

`qualification, you need Church thesis.`

Bruno http://iridia.ulb.ac.be/~marchal/