Core submeasurement structures for the low individual degree test #
Foundational measurement, submeasurement, and projective-measurement structures: the counterpart
of MIPRE/Background/LIDT/MIPStarRE/LDT/Basic/SubMeasurementCore.lean in the port of
planning/c6b-plan.md (milestone M0, section "Port conventions").
The vendored structures have their effects in the matrix algebra Op ι. Here they are generic
over an ordered ⋆-ring R ([Ring R] [StarRing R] [PartialOrder R]), with the vendored field
names verbatim: local families take R = 𝔓, the local C*-algebra of a symmetric model, and joint
families R = K →L[ℂ] K. Each lemma asks for what its proof uses: positivity facts for a
star-ordered ring, and the two projective lemmas (ProjSubMeas.outcome_mul_total_eq_outcome,
ProjSubMeas.outcome_orthogonal) for a C*-algebra, where the C*-identity
star x * x = 0 → x = 0 (CStarRing.star_mul_self_eq_zero_iff) replaces the vendored
Matrix.conjTranspose_mul_self_eq_zero.
New here #
SubMeas.map,Measurement.map,ProjSubMeas.map,ProjMeas.map: the image of a (sub)measurement under a⋆-algebra homomorphism. This is how the port places a local family on a tensor factor: the vendoredSubMeas.liftLeft(LDT/Basic/SubMeasurementFamilies.lean) becomesA.map S.L, andliftRightbecomesA.map S.R.- The bridges to the repository's measurement vocabulary (
MIPRE/Foundations/Measurement.lean):Measurement.toPOVMInandMeasurement.ofPOVMIn, inverse to each other, andProjMeas.isPVMInandProjMeas.ofIsPVMIn.
Not ported #
Every declaration of the vendored file has a counterpart here.
A paper-local submeasurement with outcomes in α and effects in the ordered ⋆-ring R.
There is intentionally no global Inhabited instance: the zero family satisfies
these raw axioms, but using it as an ambient default would silently turn later
arguments into vacuous submeasurement statements.
- outcome : α → R
- total : R
Instances For
A paper-local measurement: a POVM whose positive effects sum to the identity.
Instances For
For a trivial distinguished-outcome measurement, every outcome operator is
positive: 0 ≤ if a = a₀ then 1 else 0.
⚠️ DEGENERATE — Construct a trivial measurement where only the distinguished
outcome a₀ is the identity and all other outcomes are zero.
This is a valid POVM but highly degenerate: it is only used in vacuous
fallback branches of the proof where the error bound is ≥ 1 (see the vendored
Test/MainTheorem.lean:mainFormal_trivial_witness).
Call this function explicitly with a chosen outcome. There is intentionally no
ambient Inhabited (Measurement α R) instance: choosing a hidden
default : α would make degenerate witnesses available to paper-facing
existential statements without displaying the selected outcome.
Equations
- One or more equations did not get rendered due to their size.
Instances For
A paper-local projective submeasurement (each effect is idempotent).
There is intentionally no global Inhabited instance: any such default would
again collapse to the degenerate zero family.
Instances For
A paper-local projective measurement (complete POVM + projective).
Instances For
For a trivial distinguished-outcome projective measurement, every outcome operator is idempotent.
⚠️ DEGENERATE — Construct a trivial projective measurement where only the
distinguished outcome a₀ is the identity and all other outcomes are zero.
This is a valid projective POVM but highly degenerate: see the discussion at
Measurement.trivialDistinguishedOutcome. As for Measurement, there is intentionally no
ambient Inhabited (ProjMeas α R) instance.
Equations
- MIPRE.LIDT.Co.ProjMeas.trivialDistinguishedOutcome a₀ = { toMeasurement := MIPRE.LIDT.Co.Measurement.trivialDistinguishedOutcome a₀, proj := ⋯ }
Instances For
Derived properties #
Two submeasurements are equal when they have the same outcome operators and the same total operator.
Two measurements are equal when they have the same outcome operators.
A one-outcome submeasurement associated to a single positive operator bounded by the identity.
Equations
- MIPRE.LIDT.Co.SubMeas.singleOutcome A hA_pos hA_le_one = { outcome := fun (x : Unit) => A, total := A, outcome_pos := ⋯, sum_eq_total := ⋯, total_le_one := hA_le_one }
Instances For
The single outcome operator of singleOutcome A is A.
The total of singleOutcome A is A.
Promote a complete submeasurement to a measurement.
This is the explicit bridge from the paper's sub-measurement convention
∑ a, A_a ≤ I to the POVM convention ∑ a, A_a = I: callers must supply the
completion proof rather than relying on a degenerate default.
Equations
- A.toMeasurement hcomplete = { toSubMeas := A, total_eq_one := hcomplete }
Instances For
Promoting a complete submeasurement and forgetting completeness gives it back.
Promotion to a measurement keeps the outcome operators.
The outcome operators of a measurement sum to the identity.
Positive outcomes are self-adjoint.
Positive outcomes are self-adjoint.
Every submeasurement outcome is bounded by the total operator.
Each POVM element is bounded by the identity: outcome a ≤ 1.
Proof: outcome a = 1 - ∑_{b ≠ a} outcome b ≤ 1 since all terms are positive.
Every submeasurement outcome is bounded by the identity.
The total operator of a submeasurement is positive.
Projective submeasurement outcomes are self-adjoint (positive by assumption).
Projective measurement outcomes are self-adjoint (inherited from
Measurement.outcome_pos).
Projective submeasurements in a C*-algebra #
Each projective outcome is absorbed by the total operator.
The total operator of a projective submeasurement is itself a projector.
Distinct outcomes of a projective submeasurement are orthogonal.
Distinct outcomes of a projective measurement are orthogonal.
Any two outcomes of a ProjMeas commute.
Images under ⋆-homomorphisms #
The port's placement of a local family on a tensor factor: A.map S.L is the vendored
SubMeas.liftLeft A, and A.map S.R the vendored SubMeas.liftRight A.
The image of a submeasurement under a ⋆-algebra homomorphism.
Equations
Instances For
The outcome operators of the image are the images of the outcome operators.
The total of the image is the image of the total.
The image of a measurement under a ⋆-algebra homomorphism.
Equations
- MIPRE.LIDT.Co.Measurement.map f M = { toSubMeas := MIPRE.LIDT.Co.SubMeas.map f M.toSubMeas, total_eq_one := ⋯ }
Instances For
The image of a measurement, as a submeasurement, is the image of its submeasurement.
The outcome operators of the image measurement are the images of the outcome operators.
The image of a projective submeasurement under a ⋆-algebra homomorphism.
Equations
- MIPRE.LIDT.Co.ProjSubMeas.map f P = { toSubMeas := MIPRE.LIDT.Co.SubMeas.map f P.toSubMeas, proj := ⋯ }
Instances For
The image of a projective submeasurement, as a submeasurement, is the image of its submeasurement.
The image of a projective measurement under a ⋆-algebra homomorphism.
Equations
- MIPRE.LIDT.Co.ProjMeas.map f P = { toMeasurement := MIPRE.LIDT.Co.Measurement.map f P.toMeasurement, proj := ⋯ }
Instances For
The image of a projective measurement, as a measurement, is the image of its measurement.
Bridges to MIPRE.POVMIn and MIPRE.IsPVMIn #
A positive operator valued measure of the repository as a measurement.
Equations
- MIPRE.LIDT.Co.Measurement.ofPOVMIn P = { outcome := P.op, total := 1, outcome_pos := ⋯, sum_eq_total := ⋯, total_le_one := ⋯, total_eq_one := ⋯ }
Instances For
A measurement as a positive operator valued measure of the repository
(MIPRE/Foundations/Measurement.lean).
Instances For
The operators of toPOVMIn M are the outcome operators of M.
A family of self-adjoint idempotents summing to one, mutually orthogonal, as a projective measurement.
Equations
- MIPRE.LIDT.Co.ProjMeas.ofIsPVMIn P h = { outcome := P, total := 1, outcome_pos := ⋯, sum_eq_total := ⋯, total_le_one := ⋯, total_eq_one := ⋯, proj := ⋯ }
Instances For
The outcome operators of ofIsPVMIn P h are the P a.
A projective measurement is a projective measurement of the repository
(MIPRE/Foundations/Measurement.lean): orthogonality is ProjSubMeas.outcome_orthogonal.