Decoherence in pre-symmetric spaces.
We establish that all derivations on a semisimple Jordan-Banach algebra are automatically continuous. By showing that "almost all" primitive ideals in the algebra are invariant under a given derivation, the general case is reduced to that of primitive Jordan-Banach algebras.
For = ℝ or ℂ we exhibit a Jordan-algebra norm ⎮·⎮ on the simple associative algebra with the property that Jordan polynomials over are precisely those associative polynomials over which act ⎮·⎮-continuously on . This analytic determination of Jordan polynomials improves the one recently obtained in [5].