PhyslibAlpha.AlgebraicFramework.JordanOrderUnit.Conditioning
Conditioning a state by a Jordan projection
For a projection `p`, quadratic compression is `U_p`. Whenever `U_p` is positive and the state assigns nonzero probability to `p`, the normalized functional
`x ↦ ω(U_p x) / ω(p)`
is again a state. Positivity of `U_p` is an explicit hypothesis here: it is a theorem of JB spectral theory, not part of the weak `IsJordanOrderUnit` interface. This separation lets the conditioning construction live at its true level without postulating the missing JB theorem.
Quadratic conditioning
9 declarations
Conditioning a state on a Jordan projection
Given a Jordan projection in a Jordan order unit space and a state , if and the quadratic representation is a positive map, then the conditioned state is the unital positive linear map defined by where denotes the quadratic representation of the projection .
Evaluation of the Conditioned State
Let be a Jordan order unit space, be a Jordan projection, and be a state on such that . Suppose the quadratic representation is a positive map (i.e., it maps the positive cone of to itself). For any element , the state conditioned on the projection is evaluated as: where denotes the quadratic representation of the projection .
The conditioned state satisfies
Let be a Jordan order unit space and be a Jordan projection. Let be a state on such that , and let be the quadratic representation of . Suppose is a positive map. Then the conditioned state (defined by ) is normalized, i.e., .
The conditioned state is a positive map
Let be a Jordan order unit space, be a Jordan projection, and be a state on . Suppose that and the quadratic representation is a positive map (i.e., ). Then the conditioned state , defined by the mapping , is a positive functional. That is, for any , if , then .
Conditioning a state on a Jordan projection satisfies
Let be a Jordan order unit space and be a Jordan projection. Let be a state such that and the quadratic representation is a positive map. Then the state conditioned on , defined by the mapping , assigns the value to the projection . That is, where denotes the conditioned state.
Conditioned state for
Let be a Jordan order unit space. Let be a Jordan projection and be a state on such that . Suppose the quadratic representation is a positive map. If is Jordan-orthogonal to (that is, ), then the conditioned state evaluated at is zero, i.e., . Here, the conditioned state is defined as the functional .
Conditioning on a Jordan projection assigns zero probability to
Let be a Jordan order unit space and be a Jordan projection. Let be a state on such that . Suppose the quadratic representation of is a positive map (i.e., ). Then the state conditioned on , defined by the map , assigns the value to the algebraic complement .
Conditioning a state on a Jordan projection given quadratic positivity
Given a Jordan projection in a Jordan order unit space and a state such that , if satisfies the condition `IsQuadraticallyPositive` (which ensures that the quadratic representation of any projection is a positive map), then the conditioned state is defined as the unital positive linear map: where denotes the quadratic representation of the projection .
Evaluation of the Conditioned State
Let be a Jordan order unit space and let be a Jordan projection. Assume is quadratically positive. For any state on such that and any element , the state conditioned on (denoted by `conditionOfQuadraticPositive`) evaluates to: where is the quadratic representation of the projection .
