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We consider a net of algebras, kinematically covariant under general diffeomorphisms. A physical state induces dynamical relations, encoded by an associated net of ideals, annihilated by this state. Hence the related net of observables is in general not covariant under the full kinematical group of diffeomorphisms, but only under its subgroup of dynamical symmeties.\\ We comment on the implications of this structure, and on the possibility to introduce algebraically a natural partial order, which is related to the notions of both, a causal structure and time.
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