The identity-component bridge: faithfulness and satisfiability #
The concrete-to-abstract bridge
Physicslib4.Spacetime.LorentzianSpacetime.toAbstractIdentityComponent
(Physicslib4/AQFT/HaagKastlerCurved/Concrete.lean) instantiates the abstract
interface's isometry group Isom with the oriented identity component of the
isometry group, matching the blueprint's "isometries connected to the identity" in
Axiom 5 (def:isometric-covariance-in-curved-spacetime). This file records that the
identity component acts faithfully and that the curved Haag-Kastler axioms are jointly
satisfiable over the bridge.
The identity-component isometry group acts faithfully on the spacetime: an identity-component isometry is determined by its action on points. (Inherited from the faithful action of the full isometry group.)
Relating back to Axiom 5 over the concrete spacetime. The trivial net
over the concrete Lorentzian spacetime — with Isom the genuine
identity-component isometry group — satisfies isometric covariance
(def:isometric-covariance-in-curved-spacetime).
The curved-spacetime Haag–Kastler axioms are consistent over every geometric Lorentzian spacetime.
The group of Axiom 5 is that of toAbstractIdentityComponent, the isometries of L connected to
the identity. The witness is the trivial net, which assigns ℂ to every region; the statement
specialises Physicslib4.AQFT.HaagKastlerCurved.nonempty_haagKastlerNet to the interface of L.
Implementation note: the net has its algebras in universe 0, because the witness is built from
ℂ, which lives in Type.
Blueprint: thrm:haag-kastler-net-in-curved-spacetime-nonempty