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Connections and obstruction witnesses

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5 A distinct noncanonical connection API

5.1 The minimal compiled API

The compiled Paper III API assumes only normalization at each chart. All chart transports act on one module \(M\), so chart labels distinguish routes but not Lean types.

Definition 5.1: Noncanonical connection normalized at each chart

A minimal connection is a family

\[ \Gamma_{b\leftarrow a}\in\operatorname{Aut}_R(M) \qquad(a,b\in B) \]

with only

\[ \Gamma_{a\leftarrow a}={\mathrm{id}}_M. \]

Neither inversion on reversed edges nor the cocycle law is a field of the structure.

Formal contract: Paper III v1.0.1. Komorebi.PaperIII.Transport.Connection

At a triple \((a,b,c)\), the compiled cocycle predicate is

\[ \Gamma_{c\leftarrow b}\Gamma_{b\leftarrow a} =\Gamma_{c\leftarrow a}. \]

Flatness means this equality holds for every triple. The formal multiplicative relative defect and triangle holonomy are

\[ D^\times_{c,b,a} = \bigl(\Gamma_{c\leftarrow b}\Gamma_{b\leftarrow a}\bigr) \Gamma_{c\leftarrow a}^{-1}, \qquad H_{c,b,a} = \Gamma_{a\leftarrow c} \Gamma_{c\leftarrow b} \Gamma_{b\leftarrow a}. \]

The defect is based at the target \(c\). The holonomy is based at \(a\). Formal contract: Paper III v1.0.1. Komorebi.PaperIII.Transport.Connection.CocycleAt; Komorebi.PaperIII.Transport.Connection.Flat; Komorebi.PaperIII.Transport.Connection.cocycleDefect; Komorebi.PaperIII.Transport.Connection.triangleHolonomy

Theorem 5.2: Checked flatness consequences

For the minimal connection API, flatness implies

\[ D^\times_{c,b,a}={\mathrm{id}}_M, \qquad H_{c,b,a}={\mathrm{id}}_M \]

for every \(a,b,c\).

Formal contract: Paper III v1.0.1. Komorebi.PaperIII.Transport.Connection.cocycleDefect_eq_refl_of_flat; Komorebi.PaperIII.Transport.Connection.triangleHolonomy_eq_refl_of_flat

Proof

Flatness replaces the two-edge route in \(D^\times\) by the direct route, which cancels its inverse. For \(H\), flatness first collapses \(a\to b\to c\) to \(a\to c\), then collapses \(a\to c\to a\) to the normalized transport \(a\to a\).

Proposition 5.3: The minimal API admits nontrivial holonomy

There is a connection on three points over \(\mathbb Q\) for which transport \(0\to1\) is multiplication by \(2\), every other transport between distinct endpoints is the identity, and

\[ H_{2,1,0}(1)=2. \]

In particular \(H_{2,1,0}\ne{\mathrm{id}}\).

Formal contract: Paper III v1.0.1. Komorebi.PaperIII.Transport.twistedThreePointConnection; Komorebi.PaperIII.Transport.twisted_triangleHolonomy_apply_one; Komorebi.PaperIII.Transport.twisted_triangleHolonomy_ne_refl

Boundary 5.4: Why the minimal defect and loop are distinct

Without reverse-edge inversion, \(\Gamma_{a\leftarrow c}\) need not equal \(\Gamma_{c\leftarrow a}^{-1}\). Therefore the multiplicative relative defect \(D^\times_{c,b,a}\) and triangle holonomy \(H_{c,b,a}\) are different comparisons. The formal module proves that global flatness trivializes both; it does not identify them for an arbitrary connection.

Two directed triangles distinguish canonical transport, whose loop is identity, from a chosen connection, whose holonomy changes by conjugation.
Exact coordinate transport and connection transport are distinct. The canonical loop telescopes to the identity. A chosen connection may carry nontrivial holonomy, which transforms by conjugation under gauge.

Text description of this figure

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Figure records this separation visually: the exact coordinate route telescopes, whereas the chosen connection route may carry a nonidentity loop.

Coordinate transport and connection choice

Canonical transport compares exact coordinate descriptions of the same object. Its loops telescope. A connection supplies a separate family of comparison maps, so its loops can carry information about that choice. The distinction keeps coordinate identities separate from connection assumptions.

5.2 A stronger reversible pair API

Let \(R\) be a commutative ring, let \(B\) be a type of charts or refinement states, and let each \(C_a\) be an \(R\)-module. The chart type is not assumed finite. The following definition is deliberately not derived from analysis and synthesis.

Definition 5.5: Normalized reversible connection

A normalized reversible connection is a family of linear equivalences

\[ \Gamma_{b\leftarrow a}:C_a\xrightarrow{\;\sim\;}C_b \qquad(a,b\in B) \]

such that

\[ \Gamma_{a\leftarrow a}={\mathrm{id}}, \qquad \Gamma_{a\leftarrow b}=\Gamma_{b\leftarrow a}^{-1}. \]

No cocycle equation is included in the structure.

Formal contract: Paper III v1.0.1. Komorebi.PaperIII.Transport.ReversibleConnection

This adds heterogeneous fibers and inversion on reversed edges to the homogeneous minimal connection. The connection is still a separate choice of maps, rather than a definition of canonical coordinate transport.

Definition 5.6: Calibration and flatness

When the \(C_a\) are exact packet coordinates of one ambient module, the connection is canonically calibrated if

\[ \Gamma_{b\leftarrow a}=J_{b\leftarrow a} \quad\text{for every }a,b. \]

It is flat if

\[ \Gamma_{c\leftarrow b}\Gamma_{b\leftarrow a} = \Gamma_{c\leftarrow a} \quad\text{for every }a,b,c. \]

The canonical connection is flat. A general flat connection is proved in Theorem 6.3 to be related to it by a gauge change.

Formal contract: Paper III v1.0.1. Komorebi.PaperIII.Transport.ReversibleConnection.CocycleAt; Komorebi.PaperIII.Transport.ReversibleConnection.Flat; Komorebi.PaperIII.Transport.ReversibleConnection.canonicalConnection; Komorebi.PaperIII.Transport.ReversibleConnection.canonicalConnection_flat

The words calibrated and flat have only the algebraic meanings displayed above.

Remark 5.7: A connection on a chart graph

One may specify \(\Gamma_e\) only on the oriented edges of a chart graph, together with inverse maps on reversed edges. Path transport and loop holonomy below still make sense. A direct cocycle defect for \((a,b,c)\), however, requires a declared direct transport from \(a\) to \(c\). The pairwise API in Definition 5.5 keeps this comparison total.

5.3 Cocycle defect and triangle holonomy

The commutative ring hypothesis makes subtraction of linear maps available from this point through Section 7.

Definition 5.8: Cocycle defect

For \(a,b,c\in B\), define the additive cocycle defect

\[ \Delta_{c,b,a} = \Gamma_{c\leftarrow b}\Gamma_{b\leftarrow a} -\Gamma_{c\leftarrow a} \in{\operatorname{Hom}}_R(C_a,C_c). \]

Formal contract: Paper III v1.0.1. Komorebi.PaperIII.Transport.ReversibleConnection.cocycleDefect

The manuscript subscript order is target, intermediate, source. The Lean arguments are supplied in traversal order (a,b,c).

Definition 5.9: Triangle holonomy

The triangle holonomy based at \(a\) is

\[ H_{c,b,a} = \Gamma_{a\leftarrow c} \Gamma_{c\leftarrow b} \Gamma_{b\leftarrow a} \in\operatorname{Aut}_R(C_a). \]

It traverses \(a\to b\to c\to a\).

Formal contract: Paper III v1.0.1. Komorebi.PaperIII.Transport.ReversibleConnection.triangleHolonomy; Komorebi.PaperIII.Transport.ReversibleConnection.triangleObstruction

Holonomy is attached to the chosen connection \(\Gamma\), never to an unspecified coordinate change.

Theorem 5.10: Identity between defect and holonomy

For every triple \((a,b,c)\),

\[ \boxed{ H_{c,b,a}-{\mathrm{id}}_{C_a} = \Gamma_{a\leftarrow c}\Delta_{c,b,a}. } \]

Consequently,

\[ \Delta_{c,b,a}=0 \quad\Longleftrightarrow\quad H_{c,b,a}={\mathrm{id}}_{C_a}. \]

Formal contract: Paper III v1.0.1. Komorebi.PaperIII.Transport.ReversibleConnection.triangleHolonomy_sub_id; Komorebi.PaperIII.Transport.ReversibleConnection.cocycleDefect_eq_zero_iff_triangleHolonomy_eq_refl

Proof

Using reversibility,

\[ \begin{aligned} \Gamma_{a\leftarrow c}\Delta_{c,b,a} &= \Gamma_{a\leftarrow c} \Gamma_{c\leftarrow b} \Gamma_{b\leftarrow a} - \Gamma_{a\leftarrow c}\Gamma_{c\leftarrow a}\\ &=H_{c,b,a}-{\mathrm{id}}_{C_a}. \end{aligned} \]

Left composition by the equivalence \(\Gamma_{a\leftarrow c}\) is injective, which gives the equivalence of the two vanishing statements.

Corollary 5.11: Canonical transport has zero connection defect

If \(\Gamma_{b\leftarrow a}=J_{b\leftarrow a}\), then

\[ \Delta_{c,b,a}=0, \qquad H_{c,b,a}={\mathrm{id}} \]

for all triples.

Formal contract: Paper III v1.0.1. Komorebi.PaperIII.Transport.ReversibleConnection.canonicalTransport_zero_connectionDefect; Komorebi.PaperIII.Transport.ReversibleConnection.canonicalTransport_triangleHolonomy_eq_refl

Proof

The defect vanishes by the canonical cocycle in Theorem 4.4; apply Theorem 5.10.

5.4 Paths and endpoint independence

Definition 5.12: Connection transport along a path

For a vertex sequence \(p=(a_0,a_1,\ldots,a_n)\), define

\[ \Gamma_p = \Gamma_{a_n\leftarrow a_{n-1}}\cdots \Gamma_{a_1\leftarrow a_0}, \qquad \Gamma_{(a_0)}={\mathrm{id}}_{C_{a_0}}. \]

If \(a_n=a_0\), then \(\Gamma_p\) is the holonomy of the loop \(p\).

Formal contract: Paper III v1.0.1. Komorebi.PaperIII.Transport.ReversibleConnection.pathTransport; Komorebi.PaperIII.Transport.ReversibleConnection.VertexPath; Komorebi.PaperIII.Transport.ReversibleConnection.indexedPathTransport

Products follow path order: the first traversed edge acts on the right.

Proposition 5.13: Flat pair transport collapses to endpoints

If \(\Gamma\) is flat, then every path satisfies

\[ \Gamma_p=\Gamma_{a_n\leftarrow a_0}. \]

In particular, every loop has identity holonomy.

Formal contract: Paper III v1.0.1. Komorebi.PaperIII.Transport.ReversibleConnection.pathTransport_eq_direct_of_flat; Komorebi.PaperIII.Transport.ReversibleConnection.indexedPathTransport_eq_direct_of_flat; Komorebi.PaperIII.Transport.ReversibleConnection.indexedLoopTransport_eq_refl_of_flat

Proof

Induct on the path length. Appending \(a_{n+1}\) left-multiplies the inductive expression by \(\Gamma_{a_{n+1}\leftarrow a_n}\), and flatness replaces the two factors by \(\Gamma_{a_{n+1}\leftarrow a_0}\). For a loop, normalization gives \(\Gamma_{a_0\leftarrow a_0}={\mathrm{id}}\).

Remark 5.14

The converse trivial holonomy implies flatness depends on which loops are present in an API defined on a chart graph. In the complete pair API, triviality of every triangle holonomy is equivalent to flatness by Theorem 5.10. No theorem about topological simple connectivity is being invoked.

6 Gauge covariance and comparison with canonical transport

Definition 6.1: Gauge change

A gauge is a family of automorphisms \(G_a\in\operatorname{Aut}_R(C_a)\). It acts on a connection by

\[ \Gamma^G_{b\leftarrow a} = G_b\Gamma_{b\leftarrow a}G_a^{-1}. \]

Formal contract: Paper III v1.0.1. Komorebi.PaperIII.Transport.ReversibleConnection.Gauge; Komorebi.PaperIII.Transport.ReversibleConnection.gauge

A gauge changes coordinate representatives at each chart. The chart graph stays the same.

Theorem 6.2: Gauge covariance

The defect and triangle holonomy transform as

\[ \Delta^G_{c,b,a} =G_c\Delta_{c,b,a}G_a^{-1}, \qquad H^G_{c,b,a} =G_aH_{c,b,a}G_a^{-1}. \]

Thus flatness and triviality of triangle holonomy are gauge invariant.

Formal contract: Paper III v1.0.1. Komorebi.PaperIII.Transport.ReversibleConnection.gauge_cocycleDefect; Komorebi.PaperIII.Transport.ReversibleConnection.gauge_triangleHolonomy; Komorebi.PaperIII.Transport.ReversibleConnection.gauge_flat_iff; Komorebi.PaperIII.Transport.ReversibleConnection.gauge_triangleHolonomy_eq_refl_iff

Proof

Substitute the definition of \(\Gamma^G\). Adjacent factors \(G_b^{-1}G_b\) and \(G_c^{-1}G_c\) cancel. In the defect, both the composite and direct terms acquire the same outer factors \(G_c\) and \(G_a^{-1}\). In the loop, all inner factors cancel and only conjugation at the base remains.

Theorem 6.3: Flat connections are gauges of the canonical pair transport

Suppose the \(C_a\) are exact packet coordinate modules for one ambient module, so the canonical \(J_{b\leftarrow a}\) is available. If \(\Gamma\) is a flat normalized reversible pair connection, choose \(o\in B\) and set

\[ G_a=\Gamma_{a\leftarrow o}J_{o\leftarrow a}. \]

Then every pair transport satisfies

\[ \boxed{ \Gamma_{b\leftarrow a} =G_bJ_{b\leftarrow a}G_a^{-1}. } \]

Formal contract: Paper III v1.0.1. Komorebi.PaperIII.Transport.ReversibleConnection.flatGauge; Komorebi.PaperIII.Transport.ReversibleConnection.flat_isGaugeOfCanonical

Proof

Reversibility gives \(G_a^{-1}=J_{a\leftarrow o}\Gamma_{o\leftarrow a}\). Therefore

\[ \begin{aligned} G_bJ_{b\leftarrow a}G_a^{-1} &= \Gamma_{b\leftarrow o} J_{o\leftarrow b}J_{b\leftarrow a} J_{a\leftarrow o} \Gamma_{o\leftarrow a}\\ &= \Gamma_{b\leftarrow o}\Gamma_{o\leftarrow a}\\ &= \Gamma_{b\leftarrow a}. \end{aligned} \]

The first reduction uses the canonical cocycle twice; the second uses flatness of \(\Gamma\).

Boundary 6.4: Flat does not mean calibrated

The theorem produces a gauge relating \(\Gamma\) to \(J\). It does not prove \(\Gamma=J\) before that gauge is chosen. Conversely, nontrivial triangle holonomy cannot be removed by a gauge, because conjugation cannot turn a nonidentity automorphism into the identity.

7 Obstruction packets: local certificates and holonomy blocks

7.1 The generic compiled certificate

Let \(\mathsf{Candidate}\), \(\mathsf{Packet}\), and \(\mathsf{Residual}\) be arbitrary types, with a distinguished \(0\in\mathsf{Residual}\), and let

\[ r:\mathsf{Candidate}\longrightarrow \mathsf{Packet}\longrightarrow\mathsf{Residual} \]

be a residual function.

Definition 7.1: Solution and obstruction packet for a candidate

A candidate \(x\) is a solution when

\[ \operatorname{IsSolution}_r(x) \quad\Longleftrightarrow\quad \forall p,\ r(x,p)=0. \]

An obstruction packet for \(x\) is a pair consisting of a named packet \(p\) and a certificate \(r(x,p)\ne0\).

Formal contract: Paper III v1.0.1. Komorebi.PaperIII.NonlinearObstructions.IsSolution; Komorebi.PaperIII.NonlinearObstructions.ObstructionPacket

Theorem 7.2: Exact logical force of a local obstruction

Every obstruction packet for \(x\) proves that \(x\) is not a solution, and

\[ \neg\operatorname{IsSolution}_r(x) \quad\Longleftrightarrow\quad \text{there exists an obstruction packet for }x. \]

The reverse implication from failure to a packet witness is classical and does not require the packet type to be finite.

Formal contract: Paper III v1.0.1. Komorebi.PaperIII.NonlinearObstructions.ObstructionPacket.not_isSolution; Komorebi.PaperIII.NonlinearObstructions.obstructionPacket_of_not_isSolution; Komorebi.PaperIII.NonlinearObstructions.not_isSolution_iff_nonempty_obstructionPacket

Proof

A purported solution would make the residual vanish at the certified packet, contradicting its nonzero field. Conversely, if no packet carries a nonzero residual, then every residual is zero and the candidate satisfies the definition of solution.

What one obstruction certifies

The certificate answers one question: does this specified candidate satisfy every declared packet condition? One nonzero residual settles that question for this candidate. A statement that no candidate can solve the problem would require an obstruction for every candidate.

Boundary 7.3: Candidate-specific means candidate-specific

The theorem rules out the named \(x\). It neither constructs a solution nor shows that every candidate is obstructed. It provides no minimality, stability, computability, or classification theorem for the packet witness.

7.2 Specialization to holonomy blocks

For a reversible connection, specialize the generic residual at a fixed triangle by taking a packet label to be a pair \((\mu,\nu)\) and the residual to be the corresponding block of \(H-{\mathrm{id}}\). A nonzero block, together with its label and a proof of nonvanishing, gives an obstruction packet certificate in the sense of Definition 7.1. The reconstruction theorem below supplies the further step: vanishing of all these local residuals is equivalent to the cocycle equation at that triangle.

Fix a triangle \((a,b,c)\) and resolve the base fiber \(C_a\) by a finite complete family of idempotents \((\Pi^a_\mu)_{\mu\in I_a}\). Orthogonality may also hold, as it does for the exact range coordinate projectors below, but the compiled reconstruction theorem does not require it. In exact range coordinates, \(\Pi^a_\mu\) is simply the projector that retains component \(\mu\) and zeros the other components.

Definition 7.4: Holonomy obstruction and packet residuals

Define

\[ {\operatorname{Ob}}_{c,b,a}=H_{c,b,a}-{\mathrm{id}}_{C_a}, \qquad {\operatorname{Ob}}^{\mu\nu}_{c,b,a} = \Pi^a_\mu{\operatorname{Ob}}_{c,b,a}\Pi^a_\nu. \]

The map \({\operatorname{Ob}}^{\mu\nu}_{c,b,a}\) is the obstruction block, or packet residual, from input packet \(\nu\) to output packet \(\mu\). If it is nonzero, then \((\mu,\nu)\) and that nonvanishing proof form an obstruction packet certificate. Diagonal blocks detect holonomy within one packet. Off-diagonal blocks detect packet mixing induced by holonomy.

Formal contract: Paper III v1.0.1. Komorebi.PaperIII.HolonomyBlocks.PacketResolution; Komorebi.PaperIII.HolonomyBlocks.PacketResolution.block

The certificate records a specified holonomy defect, the label of an input and output packet, and a proof that the corresponding block is nonzero.

Theorem 7.5: Exact reconstruction and detection by obstruction blocks

The total obstruction has the exact finite resolution

\[ \boxed{ {\operatorname{Ob}}_{c,b,a} = \sum_{\mu,\nu\in I_a} {\operatorname{Ob}}^{\mu\nu}_{c,b,a}. } \]

Moreover, the following are equivalent:

  1. \(\Delta_{c,b,a}=0\);

  2. \(H_{c,b,a}={\mathrm{id}}\);

  3. \({\operatorname{Ob}}_{c,b,a}=0\);

  4. \({\operatorname{Ob}}^{\mu\nu}_{c,b,a}=0\) for every \(\mu,\nu\).

Formal contract: Paper III v1.0.1. Komorebi.PaperIII.HolonomyBlocks.obstruction_sum_blocks; Komorebi.PaperIII.HolonomyBlocks.obstructionBlocks_zero_iff; Komorebi.PaperIII.HolonomyBlocks.obstructionDetection_equivalences

Proof

Insert completeness on both sides:

\[ {\operatorname{Ob}} = \left(\sum_\mu\Pi^a_\mu\right) {\operatorname{Ob}} \left(\sum_\nu\Pi^a_\nu\right) = \sum_{\mu,\nu}\Pi^a_\mu{\operatorname{Ob}}\Pi^a_\nu. \]

Thus (iv) implies (iii), and (iii) implies (iv) by composition with the projectors. Conditions (ii) and (iii) are equivalent by the definition of \({\operatorname{Ob}}\) and additive cancellation. Conditions (i) and (ii) are equivalent by Theorem 5.10.

Why both packet indices matter

For the declared finite complete resolution, reconstruction uses both packet indices. Inspecting only diagonal blocks can miss transport from one packet to another. The full family records that mixing and reconstructs the total obstruction exactly.

Figure depicts the finite block resolution on both sides of the obstruction and the off-diagonal blocks that witness packet mixing.

A four-by-four obstruction grid highlights the possible transfer from input packet three to output packet one.
A finite complete packet resolution reconstructs the total holonomy obstruction from blocks indexed by input and output packets. A nonzero off-diagonal block is an exact witness of packet mixing.

Text description of this figure

View full-size figure (new tab)

Corollary 7.6: Witness supported in one packet

If \({\operatorname{Ob}}^{\mu\nu}_{c,b,a}\ne0\), then there is a vector \(x\) supported in packet \(\nu\) such that

\[ \Pi^a_\mu{\operatorname{Ob}}_{c,b,a}x\ne0. \]

Such an \(x\) is an exact finite witness of nonflatness.

Formal contract: Paper III v1.0.1. Komorebi.PaperIII.HolonomyBlocks.exists_packetWitness_of_obstructionBlock_ne_zero

Proof

Classically choose \(y\) on which the nonzero linear map \(\Pi^a_\mu{\operatorname{Ob}}\Pi^a_\nu\) is nonzero and set \(x=\Pi^a_\nu y\). Idempotence gives \(\Pi^a_\nu x=x\), and the required output is the chosen nonzero value.

7.3 Gauge behavior of packet blocks

Vanishing or nonvanishing of the total triangle obstruction is gauge invariant by Theorem 6.2, but a fixed packet pattern need not be. A general \(G_a\) can mix the projectors \(\Pi^a_\mu\).

Proposition 7.7: Gauge covariance when packet projectors are preserved

If \(G_a\Pi^a_\mu=\Pi^a_\mu G_a\) for every \(\mu\), then

\[ \left({\operatorname{Ob}}^G\right)^{\mu\nu} = G_a{\operatorname{Ob}}^{\mu\nu}G_a^{-1}. \]

Consequently the zero/nonzero status of each obstruction block is preserved by gauges that preserve the packet projectors.

Formal contract: Paper III v1.0.1. Komorebi.PaperIII.HolonomyBlocks.obstructionBlock_gauge_of_commutes; Komorebi.PaperIII.HolonomyBlocks.obstructionBlock_gauge_eq_zero_iff

Proof

Use \({\operatorname{Ob}}^G=G_a{\operatorname{Ob}} G_a^{-1}\) and commute \(G_a\) and \(G_a^{-1}\) through the two packet projectors. Composition by an equivalence is injective in both directions.

Boundary 7.8: Packet patterns are not absolute

Without the commutation hypothesis in Proposition 7.7, only the vanishing of the total obstruction is gauge invariant. The location of individual nonzero blocks may change under a gauge that mixes packets.

8 Products supported in packets and holonomy walks

The passage from words to walks also applies to products of different matrices. Let \(V\) be one finite packet type, let \(R\) be a semiring, and let \(B_1,\ldots,B_m\in R^{V\times V}\) be a finite sequence of possibly different packet matrices. Rows are targets and columns are sources as before.

Proposition 8.1: Packet path expansion for different matrices

For \(i,j\in V\) and \(m\geq1\), set \(i_0=i\) and \(i_m=j\). Then

\[ \boxed{ (B_m\cdots B_1)_{ji} = \sum_{(i_1,\ldots,i_{m-1})\in V^{m-1}} B_m[i_m,i_{m-1}]\cdots B_1[i_1,i_0]. } \]

When \(m=1\), the sum is over the unique empty tuple and its summand is \(B_1[j,i]\). For \(m=0\), the product is the identity and the entry is the Kronecker delta \(\delta_{ji}\). If every \(B_r[q,p]\) vanishes outside a declared relation \(\mathcal R_r(p,q)\), then the endpoint entry is zero whenever there is no packet path compatible with the successive relations.

Formal contract: Paper III v1.0.1. Komorebi.PaperIII.EdgeOperators.heterogeneousProduct; Komorebi.PaperIII.EdgeOperators.heterogeneousPathSum; Komorebi.PaperIII.EdgeOperators.heterogeneousPacketPathExpansion; Komorebi.PaperIII.EdgeOperators.SupportedStep; Komorebi.PaperIII.EdgeOperators.SupportedPath; Komorebi.PaperIII.EdgeOperators.heterogeneousProduct_apply_eq_zero_of_no_supportedPath

Proof

Expand each matrix product entry and distribute the finite sums. Induction on the factor list yields the displayed path sum, with the empty list evaluated as the identity matrix. If no supported intermediate packet exists, every summand contains an entry that is zero by its declared support relation.

Boundary 8.2: Changing packet types along a chain

The compiled theorems heterogeneousPacketPathExpansion_two and heterogeneousPacketPathExpansion_three allow different packet types at the successive stages of two- and three-factor products. The arbitrary-length theorem above permits different factors but uses one common finite packet type \(V\). A fully dependent arbitrary-length chain of changing modules and packet types remains outside the version 1.0.1 contract.

Remark 8.3: Checked specialization

When every \(B_r\) is one repeated endomorphism \(T\), the recursive specialization to packet powers is inherited from Paper I.

Inherited formal contract: Papers I–II. Komorebi.PacketNaturalityCompletion.Packets.transferBlock_pow_eq_packetPathSum

For a loop represented on one common finite scalar packet coordinate type, the proposition resolves its successive transport matrices into packet walks. If \(R\) is a ring, as in the reversible connection API, then \((H-I)_{ji}=H_{ji}-\delta_{ji}\). In particular, off-diagonal entries are unchanged. Thus a nonzero off-diagonal holonomy obstruction in this model with a common index type requires a transport word along the closed chart loop whose packet path runs from its input packet to its output packet. This conclusion requires declared block supports for the connection matrices. An arbitrary connection need not respect the transfer graph from Section 2.

9 A minimal exact example

Example 9.1: A scalar triangle

Let \(B=\{0,1,2\}\) and \(C_0=C_1=C_2={\Bbbk}\) for a field \({\Bbbk}\). Choose \(u,v,w\in{\Bbbk}^\times\) and set

\[ \Gamma_{1\leftarrow0}(x)=ux,\qquad \Gamma_{2\leftarrow1}(x)=vx,\qquad \Gamma_{2\leftarrow0}(x)=wx, \]

with reverse transports given by inverse scalars. Then

\[ \Delta_{2,1,0}(x)=(vu-w)x, \]

and the triangle holonomy based at \(0\) is

\[ H_{2,1,0}(x)=w^{-1}vux. \]

Therefore

\[ H_{2,1,0}-{\mathrm{id}} =w^{-1}\Delta_{2,1,0}. \]

The connection is flat on this triangle exactly when \(vu=w\). If the three coordinate systems are literally the same and canonical transport is used, then \(u=v=w=1\) and the obstruction vanishes. Choosing arbitrary nonzero \(u,v,w\) is a connection choice, not a consequence of changing exact packet coordinates.

Example 9.2: A transfer walk with two steps

Let a packet graph have edges \(e:0\to1\) and \(f:1\to2\), with no other edges. Then

\[ T=L_e+L_f,\qquad (T^2)_{20}=c(f)c(e). \]

The products \(L_eL_e\), \(L_eL_f\), and \(L_fL_f\) vanish by typed mismatch. Only \(L_fL_e\), corresponding to the walk \(0\to1\to2\), contributes to the \((2,0)\) entry. This example also fixes the noncommutative coefficient order.

10 Canonical coordinates for arbitrary maps

The analysis and synthesis identities are identities of functions, not only of linear maps. Consequently exact coordinate change does not become curved merely because the represented operation is nonlinear.

Proposition 10.1: Exact naturality for arbitrary functions

Let \({\mathcal A}^X_a:X\xrightarrow{\sim}X_a\) and \({\mathcal A}^X_b:X\xrightarrow{\sim}X_b\) be exact coordinate equivalences for \(X\), with inverses \({\mathcal S}^X_a\) and \({\mathcal S}^X_b\). Likewise, let \({\mathcal A}^Y_r:Y\xrightarrow{\sim}Y_r\) and \({\mathcal A}^Y_s:Y\xrightarrow{\sim}Y_s\) be exact coordinate equivalences for \(Y\), with inverses \({\mathcal S}^Y_r\) and \({\mathcal S}^Y_s\). Let \(F:X\to Y\) be any function, with no linearity or differentiability hypothesis. Set

\[ J^X_{b\leftarrow a}={\mathcal A}^X_b\circ{\mathcal S}^X_a, \qquad J^Y_{s\leftarrow r}={\mathcal A}^Y_s\circ{\mathcal S}^Y_r, \]

and define

\[ \widehat F_{r\leftarrow a} = {\mathcal A}^Y_r\circ F\circ{\mathcal S}^X_a. \]

Then

\[ J^Y_{s\leftarrow r}\circ\widehat F_{r\leftarrow a} = \widehat F_{s\leftarrow b}\circ J^X_{b\leftarrow a}. \]

If \({\mathcal A}^Z_t:Z\xrightarrow{\sim}Z_t\) is another exact coordinate equivalence and \(G:Y\to Z\) is any function, then exact coordinate representation also preserves composition:

\[ \widehat{G\circ F}_{t\leftarrow a} = \widehat G_{t\leftarrow r}\circ\widehat F_{r\leftarrow a}. \]

Formal contract: Paper III v1.0.1. Komorebi.PaperIII.Transport.exactCoordinateMap; Komorebi.PaperIII.Transport.exactCoordinateMap_comp; Komorebi.PaperIII.Transport.exactCoordinateMap_naturality

Proof

Both sides of the naturality equation reduce to \({\mathcal A}^Y_s\circ F\circ{\mathcal S}^X_a\) using \({\mathcal S}\circ{\mathcal A}={\mathrm{id}}\) in \(X\) and \(Y\). For composition, the middle \({\mathcal S}^Y\circ{\mathcal A}^Y\) cancels in the same way.

Boundary 10.2: Where nonlinear defects can enter

A nonlinear coordinate defect cannot be blamed on the exact canonical \(J\) of Definition 4.3; Proposition 10.1 makes that defect identically zero. Nonzero defects require extra structure such as a noncanonical connection, truncation, approximation, restricted domains, or failure of an operation to respect a declared packet model.

11 Nonlinear operation trees: locality and the formalization frontier

11.1 The compiled foundation of unary and binary trees

Definition 11.1: Finite grammar for operation trees

For types of input labels \(I\), constants \(K\), unary symbols \(U\), and binary symbols \(B\), the released formal grammar has four constructors:

\[ \begin{aligned} t ::={}&\operatorname{input}(i) \mid\operatorname{constant}(k) \mid\operatorname{unary}(u,t)\\ &\mid\operatorname{binary}(b,t_1,t_2). \end{aligned} \]

Given an arbitrary value type \(Y\), evaluation takes completely explicit maps

\[ I\to Y,\qquad K\to Y,\qquad U\to Y\to Y,\qquad B\to Y\to Y\to Y. \]

No algebraic, continuity, or differentiability law is imposed on these semantics.

Formal contract: Paper III v1.0.1. Komorebi.PaperIII.NonlinearObstructions.OperationTree; Komorebi.PaperIII.NonlinearObstructions.OperationTree.eval

When \(I\) has decidable equality, let \(\operatorname{inputs}(t)\) be the finite set of input labels actually occurring in \(t\).

Theorem 11.2: Input locality for operation trees

Let \(\eta_1,\eta_2:I\to Y\) be two input environments. If

\[ \eta_1(i)=\eta_2(i) \qquad\text{for every }i\in\operatorname{inputs}(t), \]

then the two evaluations of \(t\) are equal under the same constant, unary, and binary semantics. In particular, if \(\operatorname{inputs}(t)=\varnothing\), evaluation is independent of the input environment.

Formal contract: Paper III v1.0.1. Komorebi.PaperIII.NonlinearObstructions.OperationTree.eval_congr_on_inputs; Komorebi.PaperIII.NonlinearObstructions.OperationTree.eval_eq_of_inputs_eq_empty

Proof

Structural induction on \(t\). The input case is the agreement hypothesis; the constant case is reflexive; the unary case applies the induction hypothesis to its child; and the binary case applies it independently to the left and right subtrees, whose input sets form a union.

Boundary 11.3: Exact force of locality

The theorem says evaluation reads only syntactically named inputs. It does not prove that the operations are linear or nonlinear in any analytic sense, that the tree is stable, that two different trees are equivalent, or that a solution to a tree equation exists.

11.2 Typed colored extension beyond the finite contract

Definition 11.4: Finitary colored operation signature

A finitary colored signature consists of:

  • a finite type \(V\) of colors;

  • a type \(\Sigma\) of operation symbols;

  • an arity \(r(\sigma)\in{\mathbb N}\) for every \(\sigma\in\Sigma\);

  • input colors \(\operatorname{in}_\sigma:\operatorname{Fin}(r(\sigma))\to V\);

  • an output color \(\operatorname{out}(\sigma)\in V\).

A realization assigns a space \(X_v\) to each color and a map

\[ \Phi_\sigma: \prod_{q\in\operatorname{Fin}(r(\sigma))}X_{\operatorname{in}_\sigma(q)} \longrightarrow X_{\operatorname{out}(\sigma)}. \]

Outside the finite formal contract. The intended Lean target is a dependent inductive typed tree; no such declaration is part of the version 1.0.1 completion contract.

Definition 11.5: Typed operation tree and evaluation

A typed operation tree is recursively either a leaf of declared color or a node labeled by \(\sigma\), with one correctly colored child for each input slot of \(\sigma\). Evaluation is recursive:

\[ {\operatorname{ev}}(\operatorname{node}(\sigma;t_1,\ldots,t_{r(\sigma)})) = \Phi_\sigma({\operatorname{ev}}(t_1),\ldots,{\operatorname{ev}}(t_{r(\sigma)})). \]

Outside the finite formal contract. Candidate API: Komorebi.PaperIII.NonlinearObstructions.ColoredOperationTree and ColoredOperationTree.eval. This is stronger than the compiled uncolored unary–binary grammar.

11.3 Packet labelings and the multilinear first target

Suppose every \(X_v\) has a finite complete packet family \((P^v_i)_{i\in I_v}\). A packet labeling assigns an admissible packet index to each edge or node of a typed tree. For multilinear \(\Phi_\sigma\), inserting

\[ {\mathrm{id}}_{X_v}=\sum_{i\in I_v}P^v_i \]

at every input and output yields a finite sum over trees with packet labels. This is the branching analogue of inserting intermediate projectors in Proposition 8.1.

Formalization target 11.6: Finite multilinear tree expansion

The first milestone for the nonlinear module is an exact theorem saying that the evaluation of a finite tree of multilinear nodes equals the finite sum of its packet-resolved labeled evaluations. Required proof obligations include:

  1. a dependent well-typed tree syntax;

  2. finite packet-label types at every color;

  3. an explicit convention for nullary and unary nodes;

  4. multilinearity in every input slot;

  5. preservation of input-slot order without assuming commutativity of operations.

Outside the finite formal contract. Candidate target: Komorebi.PaperIII.NonlinearObstructions.ColoredOperationTree.eval_eq_sum_packetLabellings.

11.4 Connection defects at nonlinear nodes

For coordinate models of the source and target colors, an additive target coordinate space, and a chosen noncanonical connection, a pointwise node defect can be defined by

\[ \mathfrak D^\Gamma_{b,a}(\Phi) = \Gamma^Y_{b\leftarrow a}\circ\widehat\Phi_a - \widehat\Phi_b\circ \left(\prod_q\Gamma^{X_q}_{b\leftarrow a}\right). \]

This expression compares two chosen routes. With canonical exact transport in every slot it vanishes by Proposition 10.1.

Formalization target 11.7: Operation-tree defect propagation

For multilinear nodes, one expects an exact finite expansion obtained by replacing one or more nodes by their defects and transporting the remaining branches. For smooth nonlinear nodes, the corresponding chain rule is indexed by rooted partitions and Faà di Bruno trees. A formal theorem will require a fixed differentiability category, base points, derivative conventions, symmetry factors, and remainder policy.

Outside the finite formal contract. Tree-level defect identities, higher chain rules, and nonlinear norm bounds are outside the finite Lean contract. Ordinary mathematical results in these directions appear in Part II under their stated hypotheses.

Boundary 11.8: Analytic and geometric exclusions

The finite formal contract does not include convergence of an infinite tree series, existence of derivatives, a Banach-space Faà di Bruno theorem, a Baker–Campbell–Hausdorff expansion, a continuum limit, or an identification of algebraic holonomy with curvature of a smooth bundle. Part II supplies ordinary proofs for its explicit nonlinear and analytic statements. This edition does not derive a connection from data, optimization, physics, or probability.

12 Formalization ledger for version 1.0.1

Formalization status and boundaries
TopicStatusDeclaration or roadmap targetExact boundary
Packet matrix and edge operatorLean-backed IIIPacketGraph.packetMatrix; EdgeSystem.edgeOpFinite scalar matrices over a semiring; one scalar coordinate per packet.
Edge support and pair dichotomyLean-backed IIIedgeOp_eq_zero_off_support; edgeOp_mul_edgeOp_eq_zero; edgeOp_mul_edgeOp_of_composableBroken interfaces vanish; matched pairs collapse to the endpoint block with coefficient in operator order.
Typed word evaluationLean-backed IIIComposable; wordOp; wordOp_append; wordOp_eq_zero_of_not_composableList order is execution order; concatenation reverses operator-product order; nonwalks vanish.
Finite word and walk expansionsLean-backed IIIexplicitWordExpansion; walkExpansion; wordExpansion_eq_explicitWordExpansion; transferOp_pow_eq_walkExpansionActual finite tuple sum and zero-filtered composable-walk sum; finite graph and packet types.
Endpoint coefficient walk sumLean-backed IIIreverseCoefficient; Connects; transferOp_pow_apply_eq_sum_walksExact scalar endpoint entry, including the empty-walk case and noncommutative coefficient order.
Fixed reachability and orbit supportLean-backed III; inherited hull bridgetransferOp_pow_apply_eq_zero_of_no_walk; transferOp_pow_mulVec_apply_eq_zero_of_unreachable_supportFinite powers and supported seeds; the orbit-hull span conclusion uses the frozen Paper I contract.
Exact frame transportLean-backed IIIexactTransport_cocycle; exactPathTransport_eq_endpoint; exactPathTransport_loopOne frame family on a single module; arbitrary finite paths telescope and closed paths are trivial.
Exact coordinate cocycleInherited Lean-backed IINestedRefinement.refineCoordinates_comp; NestedRefinement.coordinateRefinementEquiv_transComplete finite projector coordinates, not reduction.
Typed coordinate naturalityInherited Lean-backed IINestedRefinement.coordinateOperator_comp; NestedRefinement.coordinateOperator_naturalityLinear maps over semiring modules.
Minimal connection APILean-backed IIITransport.Connection; cocycleDefect; triangleHolonomy; triangleHolonomy_eq_refl_of_flatOnly self-normalization is assumed; reverse inversion and the cocycle are not structure fields.
Twisted three-point loopLean-backed IIItwistedThreePointConnection; twisted_triangleHolonomy_ne_reflConcrete rational connection; the selected loop sends \(1\) to \(2\).
Reversible additive defectLean-backed IIIReversibleConnection; triangleHolonomy_sub_id; cocycleDefect_eq_zero_iff_triangleHolonomy_eq_reflHeterogeneous module fibers, reverse-edge inversion, and an additive defect over a commutative ring.
Reversible finite pathsLean-backed IIIpathTransport_eq_direct_of_flat; indexedPathTransport_eq_direct_of_flat; indexedLoopTransport_eq_refl_of_flatFinite pair-connection paths collapse to endpoints under algebraic flatness.
Gauge covarianceLean-backed IIIgauge_cocycleDefect; gauge_triangleHolonomy; gauge_flat_iffFiberwise algebraic conjugation; no smooth gauge theory.
Flat versus canonical transportLean-backed IIIflatGauge; flat_isGaugeOfCanonicalA chosen base chart and ambient frames exhibit every flat pair connection as a gauge transform of canonical transport.
Operation-tree localityLean-backed IIIOperationTree; OperationTree.eval; OperationTree.eval_congr_on_inputsArbitrary unary and binary semantics; only dependence on named inputs is proved.
Generic obstruction packetLean-backed IIIObstructionPacket.not_isSolution; not_isSolution_iff_nonempty_obstructionPacketExact candidate-specific logical certificate; no global classification.
Holonomy block obstructionLean-backed IIIobstruction_sum_blocks; obstructionBlocks_zero_iff; obstructionDetection_equivalencesFinite complete idempotent packet family on the base fiber; orthogonality is not required by the compiled reconstruction.
Packet witness and block gaugeLean-backed IIIexists_packetWitness_of_obstructionBlock_ne_zero; obstructionBlock_gauge_of_commutes; obstructionBlock_gauge_eq_zero_iffWitness extraction is classical; blockwise covariance requires the gauge to commute with every packet projector.
Heterogeneous matrix pathsLean-backed IIIheterogeneousPacketPathExpansion; heterogeneousProduct_apply_eq_zero_of_no_supportedPathArbitrarily many different matrices over one common finite packet type; fully typed changing-index chains compile only at lengths two and three.
Arbitrary-function coordinatesLean-backed IIIexactCoordinateMap_comp; exactCoordinateMap_naturalityExact set-level equivalences and arbitrary functions; no linearity or differentiability assumption.
Colored and smooth treesRoadmap onlyroadmap ColoredOperationTree.eval_eq_sum_packetLabellingsDependent colors, multilinear packet expansion, derivatives, and Faà di Bruno identities remain outside the contract.

12.1 Kernel-backed Paper III surface

The authoritative declaration-level contract is formalization/lean/LEAN_THEOREM_MAP_v1.0.1.md. It groups the compiled surface as follows.

  • EdgeOperators and EdgeExtensions: scalar packet matrices, typed edge and word support, finite word/walk expansions, endpoint coefficient sums, fixed-length reachability, orbit support, and common-index heterogeneous products with declared supports.

  • Transport and ReversibleConnections: exact frame transport, the minimal connection, heterogeneous reversible pair transport, additive defect and triangle holonomy, finite paths, canonical connections, and the fiberwise gauge action.

  • CoordinateNaturality and HolonomyBlocks: composition and naturality for arbitrary functions between exact coordinate systems, finite two-sided block reconstruction, equivalent obstruction criteria, packet-supported witnesses, and packet-preserving block gauges.

  • NonlinearObstructions: finite unary–binary operation trees, input locality, and candidate-specific obstruction certificates.

The release verification report records the checker-generated declaration and audit totals. The parity gate requires every fully qualified Paper III target printed beside a statement to occur in the theorem map, rejects stale or duplicate targets, and checks it against the compiled environment. KernelAudit.lean reports dependencies for the mapped and supporting theorems, and its fail-closed gate scans every compiled Komorebi.PaperIII declaration. The four inherited statement contracts remain identified separately by their Papers I–II names.

Boundary 12.1: No scope promotion by prose

The displayed endpoint coefficient formula, reachability results, reversible connection theorems, additive defect–holonomy identity, gauge covariance, holonomy-block reconstruction, packet witnesses, common-index heterogeneous path expansion, and arbitrary-function coordinate naturality are all part of the version 1.0.1 kernel-backed surface. What remains outside is the dependent fiber-valued edge-system generalization, a fully dependent arbitrary-length chain whose module and packet type change at every stage, dependent colored operation trees, packet-labeled multilinear tree expansions, nonlinear tree-defect and Faà di Bruno identities, and the analytic and geometric extensions listed above.

13 The finite contract and the nonlinear transition

Typed packet support turns the expansion of a transfer power into a walk calculus. Incompatible words vanish because their interfaces do not match. Canonical packet coordinate transport is the exact equivalence obtained from analysis and synthesis. It satisfies the cocycle law, so every finite canonical loop telescopes to the identity. Holonomy enters after a separate connection is supplied. The compiled minimal API proves that flatness makes both the relative defect and holonomy trivial, and it exhibits a nontrivial rational loop. Under the compiled reversible API, a nonzero additive triangle defect is equivalent to nonidentity holonomy, transforms covariantly under gauge, and is detected exactly by a finite family of packet blocks. Finite flat paths collapse to their endpoints. Every flat reversible pair connection is explicitly related to canonical transport by a gauge change through a chosen base chart.

These facts define the boundary of the finite formal contract. At that boundary, exact coordinates preserve composition and satisfy naturality for arbitrary functions in Paper III, while the typed linear packet coordinate counterpart remains inherited from Paper II. Nontrivial nonlinear defects must therefore be attached to additional modeling choices or to packet compatibility of the particular operation. Colored operation trees, multilinear packet labelings, and Faà di Bruno expansions remain outside this finite Lean contract. Part II develops the corresponding ordinary mathematics, including packet jets, rooted tree expansions, and explicit nonlinear obstruction theorems.

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