The diagonalization method in quantum recursion theory

As quantum parallelism allows the effective co-representation of classical mutually exclusive states, the diagonalization method of classical recursion theory has to be modified. Quantum diagonalization involves unitary operators whose eigenvalues are different from one.Comment: 15 pages, completely rewritte

Models and representation

The problem of representation has generated a sizable literature, which has been growing fast in particular over the last decade. The aim of this chapter is to review this body of work and assess the strengths and weaknesses of the different proposals