Machine-Checked Finite Event Algebras for Observer-Patch Holography
Author: Bernhard Mueller
Affiliations: Bernhard Mueller, Pragma Research Inc.
A machine-checked finite-event-algebra paper for OPH measurement surfaces, including Boolean event structure, traces, conditional expectations, and Born-Luders update rules.
Section jump
Paper release:
r2039Released: September 8, 2026
Author affiliation: Bernhard Mueller, Pragma Research Inc.
Keywords: formal verification, Lean 4, projective measurement, partition pinching, support-aware relative entropy, Lüders update, CHSH
Mathematics Subject Classification (2020): Primary 68V20; Secondary 68V15, 81P15, 81P40, 46L53.
Introduction
Finite quantum measurement is short on paper. A proof calls a matrix a state, inserts a projection, normalizes the result, and moves on. Lean asks for every condition skipped in that sentence. The matrix must be positive and have unit trace. The projection must be Hermitian and idempotent. Normalization needs a nonzero denominator. Later norm estimates require a further set of instances.
Machine-checked quantum information is an active area, spread over
several systems and several design philosophies. Mathlib [source], the central
mathematics library of Lean 4 [source], contains an order-form CHSH/Tsirelson
theorem and the IsCHSHTuple interface [source]. Physlib’s
QuantumInfo.Finite.Pinching constructs the spectral
pinching of a state as a completely positive trace-preserving map and
proves commutation, fixed-point, Pythagorean, and pinching-bound results
[sources].
Lean-Quantum provides basis-independent infrastructure for states,
channels, tensor products, Choi and Kraus representations, and trace
inequalities [source]; Lean-QIT develops a
compositional infrastructure for quantum-information theory [source]. Zhao and Yu
formalize CHSH rigidity in Lean 4 [source]. Isabelle/HOL developments
cover projective measurement, quantum computation, and the CHSH upper
bound [sources].
These developments choose different carriers for states and different
bundling conventions, and results proved in one seldom apply verbatim in
another. The engineering question underneath is interface design: which
objects stay bare predicates, which get bundled, and how finished
results are handed to the interfaces a large library expects. We make no
priority claim for projective measurement, pinching, or Tsirelson’s
inequality.
The library described here packages the side conditions of finite projective measurement into a projection-event API over Mathlib matrices. Its main input is an arbitrary projective partition of the identity. The partition induces two canonical expectations: the pinching, which deletes off-block terms and maps the matrix algebra onto the partition commutant, and the average, which projects further onto the commutative span of the partition. The same event definitions feed the Lüders update and the CHSH adapter. This keeps algebraic identities separate from results that use trace, positivity, or state normalization.
The mathematics is classical: Lüders introduced the selective update rule [sources]; pinching by a family of orthogonal projections is a standard averaging operation in matrix analysis [source] and in quantum information [source]; the bimodule and trace-duality laws proved here are the finite-matrix forms of the defining properties of conditional expectations onto subalgebras [sources]; and the CHSH combination with its quantum bound goes back to Clauser, Horne, Shimony, and Holt [source] and to Tsirelson [source]. The contribution of the library is the checked interface: definitions bundled the way Mathlib expects, exact range and uniqueness theorems for both expectations, and adapters into existing Mathlib results.
Lean declaration identifiers are printed throughout in monospaced
type, for example partitionPinchingidem; the underscore is
part of the identifier. To locate a declaration, search for the exact
printed identifier, after removing only TeX’s protective backslash
before each underscore, in the EventAlgebra/*.lean files.
In the public repository these files are under
Lean/EventAlgebra/. Table tab:modules
maps each module name to its subject matter. The top-level
EventAlgebra.lean file imports these fifteen modules
alongside the wider OPH event-algebra library.
The checked development contributes fifteen pieces:
an arbitrary supplied projective partition, independent of a selected state or spectral resolution, with its commutant bundled as a
StarSubalgebraand its span bundled with multiplication, star, commutativity, and centrality theorems;partition pinching bundled as a complex
LinearMap, with exact range and fixed-point theorems, positivity, unitality, trace preservation, the commutant bimodule law, Hilbert–Schmidt geometry, and map-level uniqueness;an exact random-unitary representation of arbitrary partition pinching as the positive uniform average over all independently signed block reflections, together with a global-sign negative control;
an orthogonal-state support countermodel showing that the totalized matrix logarithm returns zero where any support-aware extended relative entropy must return infinity;
partition averaging bundled as a complex
LinearMaponto the span, with exact range, trace duality, map-level uniqueness, tower laws against the pinching, preservation of partition Born statistics, and a classical-conditioning collapse theorem;a typed nonzero-weight Lüders state update, a support theorem and an unguarded fixed-point characterization that exhibit conditioning as a retraction onto its certainty set, and naturality of the typed update under partition pinching for commutant events;
an event-to-observable CHSH client that discharges Mathlib-compatible selfadjointness, involutivity, and cross-commutation hypotheses before applying a complementary norm-form bound;
a checked state-expectation bound that converts the norm-form theorem into a state-level CHSH bound;
a finite-state Robertson theorem for supplied density matrices and Hermitian observables, with the ordinary-commutator form, a noncommuting saturation control, and a separate zero-variance control;
the exact quotient induced by a supplied projective partition: equality after block pinching is equivalent to equality under every commutant trace test, while block pinching and commutative partition averaging both erase cross-sector corners;
an exact Tsirelson saturation witness: a declared maximally entangled state and four declared projection events inhabiting a bipartite slot-locality interface of the wider library, whose CHSH expectation equals \(2\sqrt2\) exactly, packaged with the cited upper bounds, together with a record-diagonal delimitation proving the classical bound \(2\) for every diagonal state read against four diagonal observables valued in \([-1,1]\);
an ideal static phase-POVM/count-fit structure with conditional tomography, exact diagonal/real-closure blindness, and an explicit synthetic inhabitant proving that the structure does not type source operations, producer receipts, or discharge of the phase-sensitive-effect premise;
an exact determination boundary for that structure: a coordinate characterization of the phase-sensitivity clause, run-literal pinning of the state diagonal with one free off-diagonal coordinate, affine dependence of every count frequency on that coordinate, a decidable integer receipt window on the phase counts, and the minimal phase-mass receipt (Section 11.1);
a static conformance layer for that structure: taking the committed exact lift as a declared phase-sensitive effect, a deterministic exact-arithmetic calculator, an independent verifier, and a composed Lean arithmetic receipt inhabit the static model with generated expected-frequency numerators satisfying the assumed Born-fit equations, the scaling law, and the integer receipt window (Section 11.2); and
a reproducible, version-pinned artifact with per-declaration axiom output, no proof placeholders, and a documented catalog of the Mathlib gaps, scoped-instance hazards, and workarounds met during construction (Section 12).
Two results are outside the current library. No theorem identifies an
arbitrary partition with Physlib’s spectral partition. There is no
rank-one classical-representation theorem. The CHSH bounds carry a
saturation witness (Section 10.2);
the witness state and events are declared data, produced by no theorem
from any source object. A companion module,
Dynamics/ChoiCPTP.lean, defines an explicit finite-matrix
CPTP predicate and proves both partition expectations completely
positive and trace preserving; the fifteen-module audit here covers
their event-algebra interfaces rather than recounting that companion
development.
Section 2 fixes the mathematical and Lean interfaces. Sections 3 and 4 treat projection events and selective update. Section 5 gives the bundled partition pinching and its geometry, Section 6 the random-unitary representation and logarithm-support boundary, and Section 7 the averaging expectation, the two-level structure, and the partition-relative operational quotient. Sections 8, 9, and 10 describe the state functional, finite-state uncertainty, and the CHSH clients with the exact saturation witness and its record-diagonal delimitation. Section 11 describes the ideal static phase-POVM/count-fit model, its synthetic non-discharge control, and the declared-effect conformance fixture for the phase-count layer. Section 12 records the Mathlib engagement. Section 13 reports the audit methodology, and Section 14 positions the development feature by feature.
Mathematical and formal setting
Let \(\mathrm{M}_n(\mathbb C)\) be the complex \(n\times n\) matrices, with conjugate transpose \(X\mapsto X^*\), trace \(\operatorname{Tr}\), and identity \(\mathbf 1\). Following the standard finite-dimensional setting [source], a projection event is a Hermitian idempotent \(P=P^*=P^2\), a state is a positive-semidefinite matrix \(\rho\) with \(\operatorname{Tr}(\rho)=1\), and the trace pairing is \(\mu_\rho(M)=\operatorname{Tr}(\rho M)\).
Lean represents these interfaces as predicates over Mathlib matrices:
IsEvent P is the conjunction \(P^*=P\) and \(P^2=P\); IsState rho is
positive semidefiniteness and unit trace. For functions that return
states, the library defines the subtypes ProjectionEvent n
and StateMatrix n. The split is practical. Algebraic lemmas
use raw matrices. A function advertised as a state update returns a
value whose type carries the state conditions.
Table tab:modules lists the fifteen source modules. The comparison in this work concerns their compiled interfaces and uses, not the number of declarations in each file.
| @L3.0cmL9.2cm@ Module | Principal interface |
Basic | projection events, states, trace pairing, closure and Born weight bounds |
Lueders | totalized matrix formula, typed state update, repeatability, composition, support, and fixed points |
PartitionPinching | projective partitions, bundled commutant, bundled linear pinching, exact range, geometry, bimodule law, and naturality |
PartitionAverage | partition span with closure, commutativity, and centrality; bundled averaging expectation with exact range, uniqueness, tower laws, statistics preservation, and classical conditioning |
StateExpectation | trace pairing bundled as a complex-linear functional, normalization and positivity |
Robertson | supplied-state Robertson inequality, ordinary-commutator identity, variance nonnegativity, and exact Pauli controls |
Superselection | complete operational quotient for partition pinching and cross-sector invisibility for both declared readouts |
RecordMajorization | positive uniform independent-sign random-unitary representation of arbitrary partition pinching and a global-sign negative control |
SpectralEntropyBoundary | exact support-failure density witness and totalized-matrix-logarithm no-go for support-aware relative entropy |
Tsirelson | CHSH ring identity, norm theorem, Mathlib interoperability, and event-level matrix client |
ExpectationBound | state-expectation operator-norm bound and the state-level CHSH corollary |
TsirelsonSaturation | declared Bell witness on the slot-locality interface attaining \(2\sqrt2\) exactly, packaged saturation receipt, and record-diagonal classical delimitation |
OperationalPhaseInstrument | ideal static phase-POVM/count-fit structure, conditional tomography, exact blindness receipts, and a synthetic non-discharge counterreceipt |
PhaseInstrumentDetermination | coordinate characterization of the phase clause, run-literal state pinning, affine count-frequency dependence, decidable integer receipt window, and the minimal phase-mass receipt |
OperationalPhaseAttainment | declared-effect inhabitant of the count-fit structure with generated expected-frequency numerators, stored Born-fit equations, scaling consequences, and the receipt-window clause |
Three Mathlib scopes affect compilation. ComplexOrder
equips \(\mathbb C\) with the partial
order in which \(0\le z\) means that
\(z\) is real and nonnegative.
MatrixOrder supplies the Loewner order.
Matrix.Norms.L2Operator activates the finite-matrix
operator norm and C*-ring instances used by the matrix CHSH theorems.
Without the right scope, Lean may report an instance problem even though
the required theorem is in scope; Section 12 describes
the failure modes.
Documentation tags classify results as algebra-only or trace-dependent. These tags do not define an import hierarchy. They record whether a proof uses ring, star, and norm structure alone, or also uses \(\operatorname{Tr}(\rho M)\), positivity, or normalization.
Projection events and the trace pairing
The event layer proves the expected closure rules. Zero, identity,
and \(\mathbf 1-P\) are events.
Orthogonality is symmetric. Orthogonal sums and products of commuting
events are events. Subevent absorption holds on both sides, and every
event is positive semidefinite. The declaration
IsEvent.onesubtwosmulinvolution proves that \(\mathbf 1-2P\) is a selfadjoint involution.
The CHSH adapter in Section 10 uses this
result.
The trace pairing is additive, homogeneous, compatible with finite sums, and obeys the sandwich identity \[\operatorname{Tr}(P\rho P)=\operatorname{Tr}(\rho P)\] for idempotent \(P\). Hermiticity of \(\rho\) and \(P\) implies that the pairing is real. Positivity of \(\rho\) and the event property imply \(0\le\mu_\rho(P)\) in Mathlib’s order on \(\mathbb C\); for a state the upper bound is \(\mu_\rho(P)\le 1\). The order-form statements are strictly stronger than their real-part corollaries, and both forms are provided.
The declaration isEventaddandbornWeightaddoforthogonal
returns two facts: the orthogonal sum is an event, and its Born weight
is the sum of the two Born weights. The event and orthogonality
hypotheses carry the first conjunct; the weight identity is linear and
uses none of them.
Lüders update as a partial state interface
For raw matrices, the library uses the totalized formula \[\mathcal L_P(\rho)=\mu_\rho(P)^{-1}P\rho
P.\] Lean’s field inverse maps zero to zero, so the formula is
total and covers algebraic identities in the zero-weight case. Its
return type is a raw matrix and carries no state guarantee. The typed
operation is \[\begin{aligned}
\texttt{luedersStateUpdate}:\quad&
\texttt{StateMatrix n}\to\texttt{ProjectionEvent n}\\
&\to(\mu_\rho(P)\ne0)\to\texttt{StateMatrix n}.
\end{aligned}\] This operation assumes NeZero n. The
unique \(0\times0\) matrix cannot have
unit trace, so a state-returning function must exclude that
dimension.
Proposition 1 (Checked Lüders interface). For a state \(\rho\), event \(P\), and nonzero outcome weight:
the raw formula is positive semidefinite and has trace one (
luedersUpdateisState);the updated state assigns weight one to \(P\) (
bornWeightluedersUpdateself);update is an idempotent retraction (
luedersUpdateidem);updates by commuting events compose and commute (
luedersUpdateluedersUpdateofcommuteandluedersUpdatecomm);when the state commutes with the event, the update is the normalized block restriction \(\mu_\rho(P)^{-1}\rho P\) (
luedersUpdateofcommute); andthe fixed-state equivalence \[\mathcal L_P(\rho)=\rho \quad\Longleftrightarrow\quad \mu_\rho(P)=1\] holds without a separate nonzero-weight hypothesis (
luedersUpdateeqselfiff).
The fixed-point theorem needs no nonzero-weight guard. A state fixed by a zero-weight totalized update would equal the zero matrix, which has the wrong trace. The raw function covers the zero-weight case; the state theorem does not carry a redundant premise.
The module assembles these results into a fixed-point description of
conditioning. The set certainStates collects the states
that assign weight one to \(P\).
Conditioning any state of nonzero weight lands in that set in a single
step (luedersUpdatememcertainStates), acts on the set as
the identity, and, among states, fixes exactly its elements.
Conditioning on \(P\) is therefore a
retraction of the nonzero-weight states onto its own fixed-point set.
The identity case rests on a support theorem,
muleqselfofbornWeightone: a state certain of \(P\) absorbs the event on both sides, \(\sigma P=P\sigma=\sigma\). The checked
proof compresses \(\sigma\) by the
complement event, whose weight vanishes; positive semidefiniteness
forces the zero-trace compression to vanish; and the Cauchy–Schwarz
property of the state’s quadratic form eliminates \(\sigma(\mathbf 1-P)\) itself.
Bundled arbitrary-partition pinching
A ProjectivePartition n k consists of projections \((P_i)_{i<k}\), pairwise orthogonality,
and \(\sum_iP_i=\mathbf 1\). It induces
\[\mathcal E_\pi(X)=\sum_iP_iXP_i,
\qquad
N_\pi=\{X:XP_i=P_iX\text{ for every }i\}.\] The code defines
\(N_\pi\) as
ProjectivePartition.commutant, a
StarSubalgebra defined using Mathlib’s centralizer, and
bundles \(\mathcal E_\pi\) as
partitionPinchingLinearMap. The membership theorem
memcommutantiff reduces membership to the pointwise
commutation equation.
The range is a block-diagonal commutant and need not be commutative. For this reason, we do not call it a “classical algebra”; the classical layer is the span of Section 7. The library has no theorem identifying the span with the center of the commutant, and no rank-one classical-representation theorem.
Theorem 1 (Bundled retraction and exact range). For every projective partition \(\pi\), the map \(\mathcal E_\pi\) is complex linear, unital, positive, trace preserving, and idempotent. It lands in \(N_\pi\) and fixes \(N_\pi\) pointwise. Consequently \[\mathcal E_\pi(X)=X \Longleftrightarrow X\in N_\pi, \qquad \operatorname{range}(\mathcal E_\pi)=N_\pi\] where the second equality is the equality of the linear-map range and the underlying submodule of the bundled commutant.
The corresponding declarations are
partitionPinchingunital,
partitionPinchingposSemidef,
tracepartitionPinching, partitionPinchingidem,
partitionPinchingeqselfiffmemcommutant, and
rangepartitionPinchingLinearMap. State preservation is
exposed by partitionPinchingisState.
Theorem 2 (Bimodule and Hilbert–Schmidt structure).
If \(A,B\in N_\pi\), then \[\mathcal E_\pi(AXB)=A\mathcal E_\pi(X)B.\]
Pinching is also selfadjoint for the trace pairing and satisfies the
Pythagorean identity \[\operatorname{Tr}(X^*X)=
\operatorname{Tr}(\mathcal E_\pi(X)^*\mathcal E_\pi(X))+
\operatorname{Tr}((X-\mathcal E_\pi(X))^*(X-\mathcal
E_\pi(X))),\] and hence contracts the squared Hilbert–Schmidt
quantity. A commutant-valued complex-linear map with the same trace
pairings against every commutant element equals
partitionPinchingLinearMap.
The corresponding declarations are
partitionPinchingbimodule,
traceconjTransposepartitionPinchingmul,
tracepartitionPinchingpythagoras,
tracepartitionPinchingcontraction,
tracepartitionPinchingmulcommutant, and
partitionPinchingLinearMapunique. Together they make the
map a positive, unital, trace-preserving linear projection with a
bimodule law and a trace-duality characterization; these are the
identities that characterize the trace-preserving conditional
expectation onto a subalgebra in the operator-algebra literature [sources]. The
library proves the identities directly for this map. This core module
does not instantiate an operator-algebra conditional-expectation
interface. The companion Dynamics/ChoiCPTP.lean separately
proves its custom finite-matrix IsCPTP predicate from the
same Kraus and trace identities.
Lüders naturality
If \(P\in N_\pi\), compression
commutes with pinching. After normalization, trace preservation against
commutant elements gives \[\mathcal
E_\pi(\mathcal L_P(\rho))=
\mathcal L_P(\mathcal E_\pi(\rho)).\] The raw formula is
partitionPinchingluedersUpdate. The theorem
partitionPinchingluedersStateUpdate states the same
naturality for StateMatrix n and
ProjectionEvent n: the input and output are states, and the
nonzero-weight proof is transported by
bornWeightpartitionPinching. This checks the same operation
through the bundled state and event interfaces.
Random-unitary pinching and the entropy support boundary
The support-aware majorization precursor has an exact finite
representation. For each sign assignment \(s:\{0,\ldots,k-1\}\to\{\pm1\}\), set \[U_s=\sum_i s(i)P_i .\] Orthogonality and
completeness make every \(U_s\) a
selfadjoint unitary. The independent sign characters obey \(\sum_s s(i)s(j)=2^k\delta_{ij}\), hence
\[\frac1{2^k}\sum_s U_s X
U_s^*=\sum_iP_iXP_i=\mathcal E_\pi(X).\] The real weights are
strictly positive and sum to one, so this is a literal random-unitary
representation. A two-coordinate control proves that replacing the
independent sign family by only the global pair \(\{I,-I\}\) leaves an off-diagonal matrix
unchanged and is not pinching. These statements are checked in
RecordMajorization.lean. They are an algebraic precursor;
they do not prove spectral majorization or entropy monotonicity.
The support layer cannot be bypassed by totalizing the logarithm. In
Lean, \(\log 0=0\); continuous
functional calculus therefore sends the logarithm of every projection to
the zero matrix, since a projection’s spectrum lies in \(\{0,1\}\). Consequently the raw finite
expression \[\operatorname{Re}\operatorname{Tr}\!\left[\rho(\log\rho-\log\sigma)\right]\]
is zero for the two orthogonal rank-one coordinate projections. Both are
density matrices, but the first support is not contained in the second.
Thus any extended-real divergence that returns \(+\infty\) on support failure cannot equal
this totalized raw formula. The density, support, zero-value, and
inequivalence receipts are checked in
SpectralEntropyBoundary.lean.
This is a fail-closed architectural result, not a no-go for Umegaki entropy. A complete continuation must define the support-aware extended divergence and then prove the pinching relative-entropy Pythagorean identity, spectral majorization, constrained maximum-entropy formula, and the two-level publicization information chain.
Averaging on the partition span
The same partition carries a second canonical expectation. The
partition span \[D_\pi=\operatorname{span}\{P_i\}\] is
bundled as ProjectivePartition.span. Its closure package is
proved by span induction.
Proposition 2 (The commutative layer). \(D_\pi\) contains every projector and the
identity, and is closed under multiplication and conjugate transposition
(projmemspan, onememspan,
mulmemspan, conjTransposememspan). It is
commutative (spanmulcomm). It is contained in the commutant
(spanlecommutant), and every element of \(D_\pi\) commutes with every element of
\(N_\pi\)
(mulcommofmemspanofmemcommutant): the span lies in the
center of the commutant.
Only the inclusion into the center is used here. The reverse
inclusion is not part of this module’s API; zero projectors are removed
in the separate active-label coordinate equivalence. The averaging map
is \[\mathcal
A_\pi(X)=\sum_i\frac{\operatorname{Tr}(XP_i)}{\operatorname{Tr}(P_i)}\,P_i,\]
bundled as partitionAverageLinearMap. Lean’s zero-totalized
inverse makes the terms of zero projectors vanish, so no nonzero-block
hypothesis appears anywhere in the module: a zero projector contributes
zero to both sides of every identity below.
Theorem 3 (Averaging expectation and exact range). For every projective partition \(\pi\), the map \(\mathcal A_\pi\) is complex linear, unital, positive, trace preserving, and idempotent. It lands in \(D_\pi\), fixes \(D_\pi\) pointwise, and \[\mathcal A_\pi(X)=X \Longleftrightarrow X\in D_\pi, \qquad \operatorname{range}(\mathcal A_\pi)=D_\pi.\] Against every \(C\in D_\pi\) the average is invisible to the trace pairing, \(\operatorname{Tr}(\mathcal A_\pi(X)\,C)=\operatorname{Tr}(XC)\), and any \(D_\pi\)-valued complex-linear map with this property equals the bundled average.
The corresponding declarations are
partitionAverageunital,
partitionAverageposSemidef,
tracepartitionAverage, partitionAverageidem,
partitionAverageeqselfiffmemspan,
rangepartitionAverageLinearMap,
tracepartitionAveragemulofmem, and
partitionAverageLinearMapunique; state preservation is
partitionAverageisState. The uniqueness proof mirrors the
pinching case: the difference lies in the star-closed span, is
trace-orthogonal to its own conjugate transpose, and vanishes by
faithfulness of the trace.
Theorem 4 (Two-level structure). The two
expectations compose as a tower, \[\mathcal
A_\pi\circ\mathcal E_\pi=\mathcal A_\pi=\mathcal E_\pi\circ\mathcal
A_\pi ,\] (partitionAveragepartitionPinching,
partitionPinchingpartitionAverage). The average preserves
the Born statistics of the partition, \(\mu_{\mathcal
A_\pi(\rho)}(P_j)=\mu_\rho(P_j)\) for every \(j\)
(bornWeightpartitionAverage). For a partition member \(P_j\) of nonzero weight, averaging commutes
with Lüders conditioning, and both composites collapse to the normalized
projector: \[\mathcal A_\pi(\mathcal
L_{P_j}(\rho))
=\mathcal L_{P_j}(\mathcal A_\pi(\rho))
=\operatorname{Tr}(P_j)^{-1}\,P_j\]
(partitionAverageluedersUpdate,
partitionAverageluedersUpdateproj,
luedersUpdatepartitionAverageproj).
The collapse identity is the finite-matrix form of classical conditioning: on the commutative layer, conditioning on an observed partition member replaces the averaged state by the indicator of that member, normalized. The identity is stated for raw matrices; the only hypothesis is the nonzero outcome weight.
The same partition also gives an exact operational quotient. Two matrices \(X\) and \(Y\) are declared equivalent when
\[\operatorname{Tr}(XC)=\operatorname{Tr}(YC) \qquad\text{for every }C\text{ commuting with all }P_i.\]
Theorem 5 (Complete partition quotient). For every finite projective partition, \[\bigl(\forall C\in N_\pi:\operatorname{Tr}(XC)=\operatorname{Tr}(YC)\bigr) \quad\Longleftrightarrow\quad \mathcal E_\pi(X)=\mathcal E_\pi(Y).\] Consequently, every matrix \(D\) with \(\mathcal E_\pi(D)=0\) is invisible to all trace tests from the sector-preserving commutant. In particular, each cross-sector corner \(P_iDP_j\) with \(i\ne j\) lies in that kernel.
Proof. Trace duality gives the forward statistics of the
pinched matrices. For the converse, apply the uniqueness theorem for the
commutant-valued trace-dual projection. The cross-sector statement
follows from orthogonality of the partition projectors. The complete
equivalence, kernel, and corner statements are machine-checked in
Superselection.lean. ◻
The theorem is relative to a supplied partition. It neither constructs a physical sector decomposition nor identifies the commutant with a laboratory readout algebra.
For every supplied projective partition, averaging maps surjectively
onto the commutative partition-span algebra. It factors through block
pinching, and every value commutes with the partition commutant. A
one-block rank-two control keeps the maps distinct: pinching retains a
within-block coherence which averaging removes. The finite matter
interface bundles the same map as a typed public-record adaptor. These
statements are machine-checked in B10EdgeCenterAction.lean.
The interface adds no edge object, edge-to-partition identification,
source selection, or physical detector interpretation to the
event-algebra theorems.
The bundled state expectation
For a matrix \(\rho\),
stateExpectationLinearMap rho bundles \(M\mapsto\operatorname{Tr}(\rho M)\) as a
complex-linear functional. If \(\rho\)
is a state it maps identity to one. If \(\rho\) and \(M\) are positive semidefinite, then the
expectation is nonnegative. The proof of expectationnonneg
uses a finite spectral decomposition of \(M\), cycles the trace, and reduces the
result to a sum of products of nonnegative diagonal entries; Section 12 explains why this elementary route
was chosen. Additivity and homogeneity come from the bundled
LinearMap interface and are not repeated as pointwise
lemmas.
Finite-state Robertson uncertainty
Let \(\rho\) be a supplied density matrix and let \(A\) and \(B\) be supplied Hermitian matrices. Write \[A_0=A-\operatorname{Tr}(\rho A)\mathbf 1, \qquad B_0=B-\operatorname{Tr}(\rho B)\mathbf 1,\] and define \[(\Delta_\rho A)^2=\Re\operatorname{Tr}(\rho A_0^2), \qquad c_\rho(A,B)=2\Im\operatorname{Tr}(\rho A_0B_0).\] Hermiticity makes both subtracted expectations real. The positive matrix \(\rho\) induces the seminormed pairing \[\langle X,Y\rangle_\rho=\operatorname{Tr}(Y\rho X^*).\] It may be degenerate when \(\rho\) is not faithful, which is why the formal proof uses Mathlib’s positive-semidefinite matrix seminorm rather than silently assuming a positive-definite state.
Theorem 6 (Supplied-state Robertson inequality). For every supplied finite state and pair of Hermitian observables, \[\frac{c_\rho(A,B)^2}{4} \le (\Delta_\rho A)^2(\Delta_\rho B)^2.\] The same finite pairing also gives \[\bigl(c_\rho(A,B):\mathbb C\bigr)= -i\operatorname{Tr}\bigl(\rho(AB-BA)\bigr).\] In particular, the ordinary-commutator form is \[\frac{\left|\operatorname{Tr}\bigl(\rho(AB-BA)\bigr)\right|^2}{4} \le (\Delta_\rho A)^2(\Delta_\rho B)^2.\] A zero variance on either side therefore forces the commutator readout to vanish.
Proof. Cauchy–Schwarz bounds the squared modulus of \(\langle A_0,B_0\rangle_\rho\). Its
imaginary part is no larger. Trace cyclicity identifies the pairing with
\(\operatorname{Tr}(\rho A_0B_0)\), and
scalar centring does not change the commutator. The complex identity,
the centered reduction, and the ordinary-commutator inequality are
machine-checked in Robertson.lean. ◻
The exact two-level control uses \(\rho=|{+z}\rangle\langle{+z}|\). Pauli \(X\) and \(Y\) do not commute, have unit variance, and saturate the bound with \(c_\rho(X,Y)=2\). Pauli \(Z\) and \(X\) also do not commute, while \(Z\) has zero variance and the state commutator readout vanishes. The theorem is an uncertainty statement for supplied finite inputs. It selects no state, observable, Hamiltonian, or physical instrument.
CHSH interoperability as a client
For selfadjoint involutions \(a_0,a_1,b_0,b_1\) with cross commutation,
set \[S=a_0b_0+a_0b_1+a_1b_0-a_1b_1.\]
The development first proves, in a bare ring, \[S^2=4\mathbf
1-(a_0a_1-a_1a_0)(b_0b_1-b_1b_0)\] (chshmulself). In
a nontrivial unital C*-ring this yields the operator-norm bound \(\lVert S\rVert\le2\sqrt2\)
(tsirelsonbound), the norm form of Tsirelson’s inequality
[source] for the CHSH
combination [source]. The
analytic half is short: selfadjoint involutions have norm one by the
C*-identity (normeqoneofselfAdjointinvolution), commutators
of norm-one elements have norm at most two
(normcommutatorletwo), and the square identity converts
these bounds into \(\lVert
S\rVert^2\le8\). The precise Mathlib structure is a
NormedRing, StarRing, CStarRing,
and Nontrivial. The result is stated for a unital
C*-ring.
The theorem tsirelsonboundofisCHSHTuple accepts
Mathlib’s IsCHSHTuple. The matrix instantiation,
matrixtsirelsonbound, activates Mathlib’s scoped operator
norm. The declaration matrixtsirelsonboundofevents accepts
four projection events plus the four cross-commutation equations,
constructs the dichotomic observables \(\mathbf 1-2P\), and returns the norm bound.
This gives the event layer a compiled path into the CHSH theorem.
Mathlib’s tsirelsoninequality is an order inequality in
a star-ordered real algebra [source]. The theorems in this artifact are
an operator-norm bound, its state-level corollary below, and the exact
equality witness of Section 10.2.
The state-level corollary
The bridge from norms to states is the checked bound \[\lvert\operatorname{Tr}(\rho M)\rvert\le\lVert
M\rVert\] for every state \(\rho\) and observable \(M\)
(normexpectationlel2opNorm). The proof diagonalizes the
state, cycles the trace to \(\operatorname{Tr}\!\bigl(D\,(V^*MV)\bigr)\),
dominates every diagonal entry of the conjugated observable by the
operator norm (normdiagentrylel2opNorm, by testing against
a standard basis vector), uses that unitary conjugation does not
increase the norm (normeqoneofmemunitaryGroup with
submultiplicativity), and sums the nonnegative eigenvalues to one.
Composing with the event-level norm bound gives the state-level CHSH
corollary (matrixstatetsirelsonboundofevents): for a state
and four projection events with cross-party commutation, \[\bigl\lvert\operatorname{Tr}(\rho
S)\bigr\rvert\le2\sqrt2\] for the CHSH combination \(S\) of the dichotomic observables \(\mathbf 1-2P\). The pairing \(\operatorname{Tr}(\rho S)\) is real by
starbornWeight, since \(S\) is selfadjoint, so the modulus bound is
a two-sided real bound. Section 10.2
exhibits a declared witness attaining the bound.
Exact saturation on the slot-locality interface
The module TsirelsonSaturation.lean supplies the
attainment witness. Its carrier objects come from the wider library. A
supplied bipartite slot split of the record algebra, committed as the
interface SlotLocalityInterface, which carries a norm-form
Tsirelson bound through the theorem slotlocalityreceipts.
The module inhabits that interface at two-dimensional slots with the
singleton identity Kraus family (bellSlotInterface). The
declared state is the normalized maximally entangled state on the
four-dimensional product carrier, transported to \(\mathrm{Fin}\,4\) along a fixed index
equivalence so that the typed state and expectation vocabulary of
Sections 2 and 8 applies
(bellStateisState). The four declared events are the
spectral projections of the two Pauli directions on the left slot and of
the two quarter-rotated directions on the right slot; each carries a
checked event certificate, and the four cross-party commutations are
checked on the product carrier.
Theorem 7 (Exact Tsirelson saturation). The CHSH expectation of the declared state \(\rho_{\mathrm{Bell}}\) against the combination \(S\) of the dichotomic observables \(\mathbf 1-2P\) of the four declared events equals the upper bound exactly: \[\operatorname{Tr}(\rho_{\mathrm{Bell}}\,S)=2\sqrt2 .\]
The equality is chshsaturation; its modulus form is
chshsaturationnorm. The packaged statement,
tsirelsonsaturationreceipt, is one conjunction over one
witness: the committed norm bound of the interface cited at the witness,
the state-level bound of Section 10.1
(matrixstatetsirelsonboundofevents) cited at the four
events for every state on the carrier, the state certificate with the
exact attainment in value and in modulus, and the identification of the
attaining observable with the slot-lifted CHSH operator of the interface
witness (toFourchshProdeq). The two upper bounds are cited
from the committed theorems, not re-proved.
The boundary is declared data. The saturating state and the four events are declarations of the module; no theorem produces them from committed source runs, and no physical regions, spacelike separation, or observer instruments are constructed. Identification of the supplied finite event-order structure with an observer-produced physical spacetime is not supplied, and the receipt consumes the bipartite slot split as a supplied datum.
The record-diagonal classical delimitation
The same module bounds the classical side. For convex weights \(w\) and four diagonal observables \(a_0,a_1,b_0,b_1\) valued in \([-1,1]\) on any finite carrier, the CHSH
expectation obeys the classical bound \[\Bigl|\sum_i w_i\,
(a_{0i}b_{0i}+a_{0i}b_{1i}+a_{1i}b_{0i}-a_{1i}b_{1i})\Bigr|\le2\]
(diagonalchshletwo); the matrix form, for a diagonal state
read against four diagonal readouts in the CHSH combination, is
diagonalstatechshletwo. In particular, the counted
correlation state of the wider library, a record-diagonal state
assembled from the counted joint run of the committed observer pair
\((86,247)\), obeys the bound \(2\) against every quadruple of diagonal
\([-1,1]\)-valued readouts
(countedstatediagonalchshletwo). Record-basis diagonality
is therefore insufficient for the value \(2\sqrt2\). This is a delimitation of one
fixed diagonal state with four readouts diagonal in the same basis, not
of arbitrary contextual classical experiments. The Bell state and all
four attaining settings are real matrices, so the proved gap is
entanglement, non-diagonal coherence, and noncommutativity; it does not
isolate the genuinely complex Pauli-\(Y\) direction of the declared
phase-sensitive effect, and no theorem asserts that the committed phase
lift is necessary or sufficient for attainment.
The delimitation extends from one fixed counted state to the whole
committed production surface
(SourceReachabilityDelimitation.lean). The module defines
the class of states reachable from the three source-counted occupation
laws under every operation the development commits: the walk-step
transports, the internal slot exchange, the ambient anchorings, the
marginalizations, the regional and scalar conditional expectations,
marginal products, and convex mixtures. Every state in that class
remains diagonal in the record basis with nonnegative weights summing to
one, and its CHSH value against any four record-diagonal \([-1,1]\)-valued readouts is at most \(2\), strictly below the attained \(2\sqrt2\) of the declared witness. The
witness state itself carries an off-diagonal entry of one half, so no
map that preserves record diagonality reaches that particular witness
from the class. This target-specific obstruction does not show that
every realization of the value \(2\sqrt2\) requires non-diagonal
preparation: readouts that are not slot-local with respect to the
declared split are outside the bound, and the slot-local separability
theorem for arbitrary settings is supplied by the companion module
described next. The result is a statement about the committed operation
class and the declared Bell-state witness; every conceivable
architecture extension is outside its scope. Like
Dynamics/ChoiCPTP.lean, the module is a companion in the
wider library, outside this paper’s fifteen-module count and scale
table.
The companion module ProductSplitSeparability.lean lifts
the jointly-diagonal restriction on the declared slot split. A
product-basis diagonal state with a probability diagonal is the explicit
convex combination of the point states \(e_{aa}\otimes e_{bb}\) weighted by its
diagonal entries (productDiagonalseparable), and against
any four Hermitian settings in the Loewner unit interval, two on each
slot and with no commutation assumed inside a slot, its slot-local CHSH
trace is real with modulus at most \(2\)
(productDiagonalslotLocalchshletwo). Every reachable state
on the two committed pair carriers is therefore separable across the
split and obeys the bound against all slot-local unit-interval readouts.
Slot membership is the hypothesis that carries the bound: the Bell
settings conjugated by \(\mathrm{CNOT}\,(H\otimes1)\) commute
pairwise across the wings, lie in the unit interval, and reach exactly
\(2\sqrt2\) on the product-diagonal
state \(|00\rangle\langle00|\), with
one of them in neither slot
(crossWingcommutationnotsufficient). A slot-local value
above \(2\) on a state certifies
off-diagonal record coherence; the theorem supplies neither physical
regions nor a source preparation. Like the reachability module, it is a
companion in the wider library, outside the fifteen-module count and
scale table.
An ideal static phase-POVM count fit
The module OperationalPhaseInstrument.lean makes the
interface boundary machine-visible. Its structure
IdealPhasePOVMCountModel is an ideal static model: one
matrix state, the committed web effects plus one designated phase
effect, exact binary POVM certificates, integer count literals with the
diagonal pair fixed to \((111,68)\),
and exact frequency-equals-Born equations. It contains no source
operation, completely-positive outcome maps, trace-preserving summed
channel, postmeasurement state, readback implementation, producer
identity, receipt binding, or statistical validation rule.
Every ideal model yields fixed-trace identification
(idealphasemodelcompletestomography), and its state is the
unique state fitting all exact equations
(preparationidentifiedbyexactfitdata). The construction
modelOfIdealPhaseFitData is equivalent only to the
existence of IdealPhaseFitData
(hasIdealPhaseFitiffdata); this is an algebraic fit
statement rather than a theorem establishing the phase-sensitive
effect.
Two incompleteness controls are exact. Two certified distinct states
carry identical Born data on every diagonal effect
(diagonalcontextinsufficient), so the diagonal context
alone identifies no state; the committed rotated context separates that
pair; and no diagonal effect and no complexified real effect satisfies
the phase-sensitivity clause (phaseeffectnotdiagonal,
phaseeffectgenuinelycomplex). Hence a complete static
family needs non-diagonal content and some separator outside the
complexified-real closure (phasecontextnecessary). The
theorem does not force the particular rotated effect, the designated
phase effect, their order, or an operational implementation.
The non-discharge boundary is exact. The declaration
syntheticIdealPhaseFitData chooses the rational diagonal
state with weights \(111/179\) and
\(68/179\), rotated counts \((315,401)\), and phase counts \((1,1)\). The theorem
syntheticidealphasefit proves that these chosen literals
inhabit HasIdealPhaseFit without any producer, run,
operation, or receipt input. Exact finite frequency equality is also not
a general validation criterion for sampled data. Therefore ideal fit
cannot certify custody or establish the phase-sensitive effect. A
genuine target needs source-attached CP outcome maps, a trace-preserving
summed channel, operation/readback and common-preparation semantics,
producer-bound receipts, and a preregistered statistical validation rule
(or an explicitly exhaustive deterministic semantics). Operational
additivity and composition require a separate cross-context additivity
premise.
Exact determination boundary and the integer receipt window
The module PhaseInstrumentDetermination.lean sharpens
the boundary to an exact reduction. The phase-sensitivity clause has a
coordinate characterization: for a Hermitian effect \(E\) the Born-weight gap between the two
Pauli-Y states equals \(-2\,\mathrm{Im}\,E_{01}\)
(bornWeightrhoYsubofisHermitian), so the clause holds
exactly when \(\mathrm{Im}\,E_{01} \neq
0\) (phasesensitivityiffoffdiagim). The diagonal and
complexified-real exclusions are the \(\mathrm{Im}\,E_{01} = 0\) instances, and
conjugating a committed web projector by any real matrix, gauge images
and permutations included, is excluded in one statement
(phaseeffectnerealconjugatedweb).
The committed run literals pin the model state. Every inhabitant
satisfies \(\rho_{00} = 111/179\),
\(\rho_{11} = 68/179\), and \(\rho_{10} = \overline{\rho_{01}}\)
(prepcoordinates), so one complex off-diagonal coordinate
carries the entire remaining state content. Every count frequency of
every inhabitant, in every instrument context, is an exact affine
function of that coordinate, with real coefficients determined by the
context’s effect entries (frequencyaffine). Over the
committed core the phase frequency equals \(1/2 - \mathrm{Im}\,\rho_{01}\)
(phasefrequencyeq) and the rotated frequency equals \(315/716 -
(\sqrt{3}/2)\,\mathrm{Re}\,\rho_{01}\)
(rotatedfrequencyeq); two committed-core inhabitants have
equal states exactly when all count frequencies agree
(prepeqifffrequencieseq). Positivity bounds the coordinate
by \(|\rho_{01}|^2 \le 7548/32041\)
(prepoffdiagnormSqle), which forces the decidable integer
window \(32041\,(a-b)^2 \le
30192\,(a+b)^2\) on the phase counts \((a,b)\) of every committed-core inhabitant
(phasecountsreceiptwindow). Both phase outcomes of every
committed-core inhabitant carry positive mass, and the minimal phase
count mass over committed-core inhabitants is exactly two, attained by
the synthetic inhabitant (minimalphasecountmass).
The reduction states the phase residue exactly: for a committed-core inhabitant the state diagonal, the affine dependence of every count frequency on the one free coordinate, and the admissible count window are forced by the committed diagonal literals and the committed effects. Two operational requirements are not encoded by this static type: a representation of the measurement by completely positive outcome maps with a trace-preserving summed channel and compatible effects, and a source-produced common preparation that selects the context and produces the public outcomes. The window is a necessary arithmetic condition only and carries no provenance information, since the synthetic inhabitant meets it without a source run.
Static conformance fixture for the phase-effect layer
The committed exact lift \(I/2 -
(2\sqrt{3}/3)\,i\,(QP - PQ)\), equal to the Pauli \(+Y\) projector, is taken as a declared
phase-sensitive effect. It is not a state transition or an instrument.
The module consumes that declaration and inhabits
IdealPhasePOVMCountModel over the committed core with
static integer literals. A deterministic calculator expands the Born
table of the declared effects on the declared matrix \(\mathrm{diag}(111/179, 68/179)\) in exact
arithmetic over \(\mathbb{Q}(\sqrt{3},
i)\): each context pair is the exact Born weight of the context
effect scaled to the least positive integer multiple of the reference
mass \(179\) clearing its denominator,
giving \((111, 68)\) at mass \(179\) in the diagonal and record-conjugate
contexts, \((315, 401)\) at mass \(716\) in the rotated contexts, and \((179, 179)\) at mass \(358\) in the phase context. These are
generated expected-frequency numerators, not observations or validation.
No sampling or floating-point step occurs. An independent verifier
sharing no arithmetic code rebuilds the table from the pinned payload
and demands exact agreement with every receipt field, run-mass-multiple
minimality and the integer window included. The composed receipt
(operationalPhaseAttainmentreceipt) derives, from one
antecedent bundle pinned to the declared effect and matrix, the
conjunction: committed core, declared effect in the phase slot,
vanishing off-diagonal matrix entry, committed diagonal literals, the
stored Born-fit equations and their cross-multiplied scaling
consequences, positive integer masses, and phase counts inside the
registered window. The Lean theorem does not prove leastness, source
reachability of this two-dimensional matrix, or receipt provenance; the
external verifier checks the deterministic least-denominator arithmetic
separately. The instrument representation, the source-produced
preparation, and the independent cross-context additivity premise are
not supplied.
The module LuedersPhaseInstrument types the channel
clauses as a structure PhaseInstrument on the eight
committed contexts: outcome maps that are completely positive,
trace-nonincreasing on positive-semidefinite inputs, summing to a
trace-preserving channel per context, and inducing the committed effect
table. The Lüders maps \(X \mapsto
EXE\) inhabit it (luedersPhaseInstrument) with a
singleton Kraus family, and the normalized post-measurement state is
certain of its effect (luedersPhaseInstrumentrepeatable).
On \(\mathrm{diag}(111/179, 68/179)\)
the outcome traces reproduce the fixture frequencies, with \(1/2\) in the phase context, whose
post-measurement state is the declared \(+Y\) projector itself; the phase and
diagonal values are also obtained by direct matrix computation through
the outcome maps, with no use of the stored Born-fit equations. A
swap-twisted instrument meets every channel clause with the same induced
effects, differs on the record entry, and fails repeatability
(effecttabledoesnotdetermineinstrument). Certain-state
invariance does select it: a Kraus-form outcome map with projective
induced effect \(E\) that leaves every
state certain of \(E\) unchanged is the
Lüders map \(X \mapsto EXE\), and
conversely, so among Kraus-form instruments with the committed effects
the Lüders instrument is exactly the certain-state-invariant one; the
swap-twisted instrument fails that invariance, and the committed
repeatability clause (the normalized output is certain of its effect) is
strictly weaker and does not select
(InstrumentSelectionByCertainStates). Certain-state
invariance is a declared operational hypothesis, no source implements
it, and the instrument representation, the source-produced preparation,
and cross-context additivity are not supplied. The module is a companion
in the wider library, outside the fifteen-module count and scale
table.
The companion module SourcePhaseSelection asks what
phase-sensitive effect candidates can be built from source-attached
algebraic fields. Its generator reads two inputs only, the six exact
rows of the declared two-dimensional irreducible representation and the
diagonal record projector, forms the projector orbit, and enumerates the
twelve noncommuting orbit pairs. A declared complexification adapter
sends each nonzero real skew commutator \(C\) to \(I/2-iC/(2|C_{01}|)\). The generated effect
values are exactly the two Pauli-\(Y\)
projectors (generatedeffectvaluesexact); the first pair in
the current stable label order has the \(+Y\) projector, which equals the declared
lift and the instrument’s phase slot
(currentfirstlabelledeffecteqsourcePhaseLift,
currentfirstlabelledeffecteqdeclaredluederseffect). Eight
pairs give \(+Y\) and four give \(-Y\), so the theorem is effect-value
equality rather than witness uniqueness. Reversing the commutator order
for a fixed pair swaps the transpose effects
(effectMatrixnegativeeqtransposepositive), but reversing
the event list does not generally flip the conventional first-labelled
orientation: the last current pair is also \(+Y\). No theorem source-selects the
first-label rule. The robust result is the unordered pair of \(Y\) projectors under the declared adapter.
The module’s enabled-domain relation reproduces the canonical \(36/12\) split between state-changing Lüders
updates and equality stutters (changingEnabledCellCensus,
alreadyOperationEnabledCellCensus). It constructs no
instrument and supplies no preparation, outcome, readback, or
provenance; the phase-sensitive-effect declaration keeps the adapter and
orientation choice. Like the reachability module, it is a companion in
the wider library, outside the fifteen-module count and scale table.
The companion module SourcePhaseInstrumentOutcomeBridge
joins those generated source semantics to the declared Lüders phase
instrument. It maps every generated \(+Y\) event to the declared phase-outcome
index \(0\) and every generated \(-Y\) event to index \(1\), then proves exact equality of the
generated effect with that entry of the committed effect pair
(generatedEffecteqcommittedPhaseOutcome). All five
generated state matrices are positive semidefinite with trace one
(stateMatrixisState). For each of the 48 enabled source
steps the corresponding Born weight is nonzero, and the normalized
output of the indexed declared Lüders map equals the generated semantic
result matrix (sourceStepnormalizedluedersoutcomeeqresult).
This is a matrix-level compatibility theorem. The index is not a
recorded public outcome, and the result neither source-selects nor
implements the Lüders instrument, nor supplies one common cross-context
preparation, readback, run binding, provenance, or custody. The clauses
are conjoined in
sourcePhaseInstrumentOutcomeBridgereceipt.
The companion module SourcePhaseCommonPreparationHull
identifies the exact common-support surface of the generated phase
relation. Exactly the three real orbit states admit all twelve generated
phase events (hasAllPhaseEventsiff). Their normalized real
mixture with weights \[\frac{265}{537},\qquad
\frac{136}{537},\qquad \frac{136}{537}\] is exactly the declared
run state; this is theorem
commonSupportMixtureeqcommittedRunState. Equality to that
matrix uniquely determines all three coefficients, without assuming
normalization (commonSupportMixturecoefficientsunique).
Each common-support state assigns weight \(1/2\) to either generated Pauli-\(Y\) orientation, and every common-support
state/event pair inherits the normalized declared Lüders-outcome
equality. The declared run matrix is not any generated state, no
generated source step starts from it, and the result of every generated
phase event lacks all-event support. This is retrospective convex-hull
compatibility, not a source-produced or enabled common preparation. The
pointwise one-step cells supply no convex-lift, mixing, reset,
re-preparation, or sequential schedule. The twelve generated events are
not the eight public instrument contexts, and the theorem supplies no
instrument implementation, public outcome, readback, run binding,
provenance, custody, cross-context additivity, or physical attachment.
The clauses are conjoined in
sourcePhaseCommonPreparationHullreceipt.
The module SourcePhaseBornWeightBoundary proves the
exact single-shot identity \[\operatorname{Tr}(\rho
P_{+Y})=\frac12-\operatorname{Im}(\rho_{01})\] for every
normalized two-dimensional state. Thus a non-half weight for the current
conventional first-labelled \(+Y\)
effect under the declared adapter/order weight requires nonzero
imaginary off-diagonal coherence; real off-diagonal coherence alone is
insufficient (statecurrentfirstlabelledweighteqhalfsubim).
It then places that conventional effect and the enumerated
source-reachable class behind an explicit prospective preparation-bridge
interface. If such a bridge maps reachable matrices to states and
preserves record diagonality, the selected \(+Y\) effect has Born weight exactly \(1/2\) on every bridged preparation
(reachablerecordPreservingphaseweighthalf). On a
record-diagonal state the generated \(-Y\) orientation and the diagonal
comparator \((1/2)I\) have the same
weight. Constant diagonal and off-diagonal bridges show that the
preservation hypothesis is logically inhabitable and load-bearing. Both
are mathematical controls that ignore their inputs. The result derives
no source bridge or operation, common preparation, public outcome,
sequential instrument behavior, operational readback, run, provenance,
or custody.
Working over Mathlib: scopes, gaps, and affordances
This section records what the construction consumed from Mathlib,
where the library resisted, and which workarounds closed the gaps. The
artifact repeats the catalog in the notes file
MATHLIBNOTES.md.
Scoped instances
The three scopes of Section 2 share a
failure mode. The partial order on \(\mathbb
C\) and the Loewner order are scoped instances; every \(0\le z\) goal and every
positive-semidefiniteness statement over \(\mathbb C\) elaborates only when the scope
is open, and a missing scope surfaces as an instance-resolution error
far from its cause. ComplexOrder also carries the scoped
ordered-ring structure on \(\mathbb C\)
that supplies multiplicativity of nonnegativity inside the complex
order. There is no global norm on Mathlib matrices; the operator norm,
the NormedRing structure, and the CStarRing
instance arrive only under Matrix.Norms.L2Operator, so the
entire Tsirelson section lives behind that scope. The
Nontrivial instance for \(n\times
n\) complex matrices with \(n\ne0\) did not synthesize and is
constructed by hand, entrywise. The matrix unitary group is a submonoid
distinct from Mathlib’s unitary bundle, so its norm-one
property is also proved by hand from the C*-identity.
Gaps and workarounds
Bilinear trace positivity. Mathlib proves \(0\le\operatorname{Tr}(A)\) for a single
positive-semidefinite matrix and covers sandwich forms \(BAB^*\). The bilinear statement \(0\le\operatorname{Tr}(AB)\) for two
positive-semidefinite factors is absent. For Born weights the gap costs
nothing, because \(\operatorname{Tr}(\rho
P)=\operatorname{Tr}(P\rho P)\) for idempotent \(P\). For expectationnonneg the
natural route, the C*-order equivalence between nonnegativity and Gram
factorization, fails to elaborate: two continuous-functional-calculus
instances are not synthesized for the matrix algebra under its product
topology. The proof takes the elementary route instead, a spectral
decomposition of the observable followed by a trace cycle and termwise
nonnegativity, in about a dozen lines.
The ring identity. The square identity behind the Tsirelson
bound is pure noncommutative ring algebra under side relations: four
involutivity equations and four cross commutations. Lean has no
noncommutative analogue of linearcombination, and
noncommring does not use hypotheses. The checked proof
builds a small confluent rewrite system. Each commutation hypothesis is
recast as a universally quantified, association-compatible form \(b(ax)=a(bx)\), and each involution as \(a(ax)=x\); applied through
simp only, these rules move every \(b\) past every \(a\) in right-associated words and cancel
adjacent equal letters. Every rewrite strictly decreases the number of
letter pairs out of normal order, so the system terminates, and
abel closes the remaining additive goal.
Higher-order motives. Two steps needed their motives spelled out. The binary span-induction principle behind the closure package of Proposition 2 does not infer its motive from the goal; the predicate is passed explicitly. Rewriting with the unit-trace equation inside a hypothesis whose proof term mentions the bundled state predicate fails the motive typecheck, because the state predicate itself contains the trace being abstracted; a term-level chain through injectivity of the real embedding replaces the rewrite.
Rewriting discipline. Unfolding the definition of the Born weight rewrites the first syntactic occurrence, which in normalized expressions is often the normalizing scalar \(\mu_\rho(P)^{-1}\) instead of the intended trace argument. The affected proofs isolate each trace identity as a standalone step with explicit arguments to the trace commutation and cycling lemmas.
Affordances
The Matrix.PosSemidef API is complete enough that the
development never unfolds the definition of positive semidefiniteness:
sandwich closure, sums, scalar multiples, diagonal nonnegativity, trace
nonnegativity, and the Gram construction cover every need, and the
scalar lemma accepts a complex scalar that is nonnegative in the complex
order, which makes the Lüders normalization a single application. Trace
faithfulness is available in two forms: the conjugate-transpose
criterion powers the uniqueness theorems of both expectations, and the
zero-trace criterion together with the Cauchy–Schwarz property of
positive matrices powers the support theorem of Section 4. On the analytic side, the
C*-identity, the norm-one property of the unit, and submultiplicativity
reduce the norm half of the Tsirelson bound to about forty lines over
the four-typeclass signature, and the matrix case is a two-line
instantiation behind the norm scope. The state-expectation bound of
Section 10.1 rests on the scoped norm
being definitionally the Euclidean operator norm: the type synonym is
identity-transparent, so a show converts Euclidean-space
statements to raw matrix-vector algebra, and the basis-vector,
submultiplicativity, and eigenvalue-trace lemmas finish the proof in
about sixty lines. Mathlib’s CHSH file supplied the
IsCHSHTuple bundle, so interoperability with the order-form
theorem cost one conversion theorem.
Artifact evaluation and proof audit
The source is a Lake project. Its toolchain pins
leanprover/lean4:v4.29.1; its manifest pins Mathlib commit
5e932f97dd25535344f80f9dd8da3aab83df0fe6. Build the library
with
lake build EventAlgebra.
The canonical Lean modules are publicly available in the Observer Patch Holography repository [source]. The exact source snapshot is the repository revision containing this manuscript and its built PDF; the manuscript source accompanies the submission.
Table 1 describes the fifteen modules discussed here and the umbrella root. Other modules imported by the broader root are outside this paper’s count. The comparison in Section 14 concerns interfaces, not counts.
| Module | Lines | Audited declarations |
|---|---|---|
Basic |
302 | 25 |
Lueders |
294 | 14 |
PartitionPinching |
474 | 27 |
PartitionAverage |
513 | 30 |
StateExpectation |
105 | 4 |
Robertson |
416 | 20 |
Superselection |
197 | 9 |
RecordMajorization |
322 | 6 |
SpectralEntropyBoundary |
161 | 5 |
Tsirelson |
275 | 8 |
ExpectationBound |
174 | 4 |
TsirelsonSaturation |
834 | 39 |
OperationalPhaseInstrument |
878 | 40 |
PhaseInstrumentDetermination |
504 | 24 |
OperationalPhaseAttainment |
373 | 22 |
EventAlgebra (root) |
172 | 0 |
| Total | 5994 | 277 |
Every public result discussed in the paper appears under its Lean
name. The modules end with #print axioms commands for the
principal declarations, and a clean build emits the generated output.
The 277 audited declarations report only subsets of propositional
extensionality, classical choice, and quotient soundness, the standard
Lean/Mathlib base. No declaration reports sorryAx, and a
source scan finds no sorry placeholder in these
modules.
The submitted API uses every orthogonality hypothesis in its orthogonal-sum theorem. The sequential-update theorem has no unused event premise. State update is typed and excludes dimension zero. The fixed-point equivalence has no nonzero-weight guard, and the averaging module carries no nonzero-block hypotheses. The commutant, span, and both expectations are bundled, and the CHSH adapters are clients of the event definitions.
The repository contains the toolchain, Lake manifest, source modules, build command, in-source axiom queries, and a Creative Commons BY-NC-SA 4.0 license. No persistent archive identifier is claimed.
Feature-level comparison
Table tab:comparison compares compiled features. It does not treat a count of elementary lemmas as a research contribution.
| @L2.1cmL4.25cmL6.0cm@ Feature | Closest checked infrastructure | This artifact |
| Projective measurement | Isabelle/HOL projective-measurement developments; state/measurement interfaces in current Lean libraries | finite matrix event predicate, typed event/state subtypes, closure and trace-pairing lemmas; treated as prerequisite; no priority claim |
| Pinching | Physlib spectral pinching is a state-selected bundled CPTP map with fixed-point and geometric results | arbitrary supplied
projective partition; bundled linear map and commutant; companion
custom-IsCPTP proof; no Physlib correspondence
theorem |
| Retraction structure | operator-algebra conditional expectations and channel interfaces | exact range/fixed points, positive/unital/trace-preserving, bimodule, Hilbert–Schmidt geometry, map-level trace-duality uniqueness |
| Random-unitary and entropy boundary | random-unitary dephasing and support-aware Umegaki divergence in finite quantum information | exact independent-sign average for arbitrary supplied partitions; a support-failure countermodel showing that totalized matrix logarithms cannot encode the extended divergence |
| Commutative layer | conditional expectations onto commutative subalgebras in operator-algebra practice | bundled averaging expectation onto the partition span, exact range and uniqueness, tower laws with pinching, Born-statistics preservation, classical-conditioning collapse |
| Lüders update | Isabelle projective measurement and general channel infrastructure | raw formula plus typed partial state API, support theorem, unguarded state fixed-point equivalence, typed naturality with arbitrary-partition pinching |
| CHSH/Tsirelson | Mathlib order theorem; Isabelle upper bound; Lean CHSH rigidity | complementary norm theorem, event-level client, state-expectation corollary, and an exact saturation witness on declared data; fixed record-diagonal states with jointly diagonal readouts capped at the classical bound |
| Reproducibility | public CI and archived releases are common best practice | pinned Lean/Mathlib, an exact repository snapshot, clean build instructions, and declaration-level axiom queries; no DOI claim |
Physlib provides more channel structure: its spectral pinching is a
CPTPMap [source]. This artifact accepts a
supplied partition that need not come from the spectrum of a state. The
two APIs therefore have different inputs, and no correspondence theorem
connects them.
Lean-Quantum and Lean-QIT cover a larger part of quantum information [sources]. Here, the scope is limited to connections among projections, commutants, spans, the two expectations, selective update, and Mathlib’s CHSH interface.
Limitations and conclusion
The library connects projection events, Born weights, a typed Lüders update, arbitrary projective partitions, the two expectations of a partition, and event-level CHSH bounds in norm and state form, with an exact saturation witness and a record-diagonal classical delimitation on the same event API. The pinching has the bundled commutant as its exact range and the average has the bundled span; each map is the unique trace-dual projection onto its range, the two compose as a tower, and both interact with Lüders conditioning by checked theorems. The supplied-state Robertson bound, the independent-sign representation, the logarithm-support boundary, and the partition-relative operational quotient use the same finite matrix API. Each formal statement in the paper points to a declaration in the repository source.
The construction follows one pattern: state algebraic content as predicates over raw matrices, move to subtypes exactly where an API promises a state, bundle the carrier and the projection so that range and uniqueness theorems are exact, and hand finished objects to Mathlib interfaces through small adapters. The pattern is independent of measurement theory and applies to other finite-dimensional operator-algebra developments over Mathlib.
The companion Dynamics/ChoiCPTP.lean establishes
complete positivity and trace preservation for both expectations under a
custom finite-matrix IsCPTP interface. There is no theorem
connecting the supplied partition to Physlib’s spectral pinching and no
rank-one classical specialization. The CHSH saturation witness rests on
declared data: no theorem produces the state or the events from a
committed source run. The ideal static phase-fit model has an explicit
synthetic inhabitant and is not an operational instrument. The entire
development is finite-dimensional and says nothing about normal maps on
infinite-dimensional von Neumann algebras.
The proved surface contains the arbitrary-partition pinching with its exact range and bimodule law, the averaging expectation with its tower and classical-conditioning laws, typed Lüders naturality, the complete partition-relative quotient, the supplied-state Robertson inequality, the state-level CHSH corollary, the exact saturation receipt with its record-diagonal delimitation, and the ideal phase-fit model with its synthetic non-discharge counterreceipt; the companion module adds the custom CPTP proofs. It contains no Physlib spectral-partition correspondence and no source-selected quantum instrument; the two-qubit saturation witness consists of declared data, and the operational phase instrument and its source custody are not constructed.
Declarations
Funding. No funding was received for this work.
Competing interests. The author declares no competing interests.
Author contributions. Bernhard Mueller is the sole author, designed the study, reviewed the formal development, and takes responsibility for the manuscript and artifact.
Data and code availability. No empirical data were generated. The canonical Lean source is available in the Observer Patch Holography repository [source]. The repository revision containing this manuscript provides the Lean source, pinned dependency files, build instructions, and declaration-level axiom queries under a Creative Commons BY-NC-SA 4.0 license. No persistent archive identifier is claimed.
AI Assistance Disclosure
This research project used research-grade commercial models, including Anthropic’s Fable and OpenAI’s GPT-5.6-Sol, for research support, software development, editing, and synthesis. The authors are responsible for the paper’s claims, methods, and final text.