On 30-Dec-02, you wrote: > Dear Stephen, ... > [Bruno]It is perhaps up to you to show me a quantum computable function not > being classicaly computable. But if you succeed you will give me > something like an unitary transformation, and then I will show you > how to write a classical program emulating this unitary > transformation. See Pour El and Richard's book on how to conceive > differential equations with non computable solutions (but still > locally generable by the UD though), but anyway, linear quantum > waves are classicaly emulable. It is a tedious but conceptually not > so hard exercise. > > >> >> I can not see how this is possible given that (as Svozil et at >> state in http://tph.tuwien.ac.at/~svozil/publ/embed.htm ) "for >> quantum systems representable by Hilbert spaces of dimension higher >> than two, there does not exist any such valuation s: LŪ {0,1} ... >> there exist different quantum propositions which cannot be >> distinguished by any classical truth assignment."

This is the Kochen-Specker theorem. It depends on the existence of an Hermitean operator to implement any function of variables. You should be aware that this problem is avoided by Bohm's intepretation of quantum mechanics - so it is not inherent in the physics. See http://www.math.rutgers.edu/~oldstein/quote.html Brent Meeker There is a theory which states that if ever anybody discovers exactly what the Universe is for and why it is here, it will instantly disappear and be replaced by something even more bizarre and inexplicable. There is another theory which states that this has already happened. -- Douglas Adams (Hitchhiker's Guide to the Galaxy)