The source support of the realized family, its lift groupoid and its interfaces
The preceding two sections give the lift of one finite lattice: an admitted antecedent (Proposition 6.1), a redundant realization, its readout and its section (Theorems 7.1 and 7.2). The supplied construction, however, is not one lattice. It is a countable family of finite histories, indexed by a cutoff, a period and a scale level, together with comparisons between them, auxiliary reference volumes, coefficient spaces of field labels, an imported free comparison theory and several successive limits. This section develops the source-side structure that is needed to carry that family, and states what that structure does and does not determine. It has four parts: the admitted support; the lift groupoid of a single leaf; the sectors and interfaces of the supplied construction, with the status of each discrepancy; and the separation of what follows from the source side from what is supplied as realization data. Nothing in this section is used as a hypothesis by the supplied derivations that follow; it is the frame in which their source–readout formulations are stated.
8.1 A fan of marked dependencies
Let be a nonempty countable set. The fan Φ
has vertices
r
, dependency preorder generated by r
for every
, and one marked token
for each
, with support
r
. The lineage, invariant and intrinsic boundary data of
are those of the walking marked dependency
, transported along the map
Φ
r
. For a subset
write Φ
for the corresponding subfan.
Proposition 8.1 (Admission of the fan). For every countable the fan Φ
is admitted. More precisely:
1. for finite Φ
is obtained from
copies of
by successive attachments along the root face
, and is admitted;
2. for the inclusion Φ
Φ
is a strong map, and Φ
is the directed colimit of the Φ
over finite
; this colimit is stabilizing;
3. distinct leaves are incomparable: for neither
nor
Proof. The admission construction of [3] is the least isomorphism-saturated class containing the initial witnesses, among them, and closed under the specified finite attachments along source faces, presentation-preserving retracts and stabilizing directed colimits. The root
of
is a source face: it is predecessor-closed, and it is lineage-and boundary-closed because the marked token is not supported in it and the intrinsic boundary is empty. (1) Attaching a further copy of
to Φ
along the identification of its root with r is a pushout along that face. The attaching map is strong and reflects marks, since no marked support lies in the face. The pushout adds one vertex, one strict pair and one marked token, and leaves every existing support, strict pair and lineage datum unchanged; the candidate conditions (finite nonempty supports each containing a strict pair, well-typed inherited data) therefore hold in Φ
. Induction on
gives admission. (2) An inclusion of subfans preserves the preorder, the marking, the supports with their strict pairs and the inherited data, and is injective; it is therefore strong. Every finite set of vertices and tokens of Φ
lies in some Φ
with
finite, and its preorder, supports and inherited data are the same in every larger subfan; this is the stabilization condition. (3) The preorder is generated by the pairs r
, and neither a pushout along the root nor the colimit adds a relation between leaves.
This is the same admission that supports the family of prepared paths in the gravitational reconstruction [4]; only the index set and the realized sector differ. The literal preparation of a leaf is
the preparation of Proposition 6.1, by restriction along
Proposition 8.2 (What the support determines).
, the strong automorphisms of Φ
are exactly the maps fixing r and permuting the leaves, with
; thus Aut(Φ
= Sym(
2. The fold mapr) = 0
, is strong, and
for every
3. Every finite family of marked tokens of Φ lies in a finite admitted subfan.
Proof. (1) A strong automorphism preserves the preorder, hence fixes the unique vertex that lies strictly below at least two others, and permutes the remaining vertices. It preserves supports, so it sends to the token supported on
r
. Conversely each permutation of
defines such a map, and it preserves the inherited data because these are transported from the same
along the maps
preserves the preorder and the strict pairs r
1, carries each support bijectively onto
, so is injective on marked supports, and preserves the inherited data by their definition. (3) is Proposition 8.1(2).
The three statements have direct consequences for the reconstruction. By (1), nothing on the source side distinguishes one leaf from another. Any assignment of cutoffs, periods or scale levels to leaves, any order among them and any relation between two leaves is therefore realization data. By (2), the single-cell presentation of Proposition 6.1, in which one marked occurrence supports the whole realized tuple, is the image of the fan presentation under a strong map; the two presentations carry the same realized record, and every statement of the preceding sections applies leaf by leaf. By (3), every estimate of the supplied construction, which always concerns finitely many histories at a time, is a statement over an admitted finite support, and a limit is a readout of a net of realized data over the colimit; it is not a new source object.
8.2 The lift groupoid of one leaf
Searchable transcription
Fix one finite lattice (V, E), connected as a graph, with Z = GV × GE, U = GE and π, σ as in Theorem 7.1. Two groups act on Z: the frame group GV by k · (r, A) = (kr, (kxAek−1 y )e), and the lifted gauge group GV by (r, A) · h = ((rxh−1 x )x, A). The two actions commute. Let E be the action groupoid of GV frame × GV gauge on Z, and Comp the action groupoid of the gauge group on U, (h · U)e = hxUeh−1 y . These are the groupoids of realized histories and of allowed comparison isomorphisms on this branch.
Theorem 8.3 (The realization is an equivalence of groupoids). The assignment
is a functor
Comp, and it is an equivalence: it is surjective on objects, full and faithful. Consequently
Searchable transcription
1. for every U ∈U the lift groupoid Lift(U) = E ×h
Comp {U} is nonempty and contractible: any
two recovery witnesses (z, φ), (z′, φ′) of U are related by exactly one arrow of E compatible
with φ, φ′;2. for the automorphism group of
in
is
Searchable transcription
AutE(z) = {(k, h) : kxAek−1
y
= Ae, hx = r−1
x kxrx} ∼= StabGV (π(z)),and for any base vertex evaluation
identifies Stab
with the centralizer in
of the holonomy group of
at
Proof. For) and (
) one computes
) =
, so Π is a functor. It is surjective on objects because
= id. Fullness:
let
). Then
and
have the same readout, so by Theorem 7.1 there is
with
, and (
) is an arrow
over
. Faithfulness: if (
) and (
) are arrows
, then
), and freeness of the frame action gives
. An equivalence of groupoids has contractible homotopy fibres, which is (1): an object of Lift(
) is a pair (
) with
a gauge transformation carrying
, and an arrow (
) is an arrow (
with; here
is forced and then
exists and is unique by fullness and faithfulness. (2) An arrow (
) fixes
) exactly when
and
; the first equation
gives
, and then
Stab(
)); conversely
each such
determines
, which fixes
. Finally, if
stabilizes
then
for every path
is determined by
, and applying this to closed paths shows that
commutes with every holonomy at
; conversely, for
in that centralizer the formula
is independent of the path and defines a stabilizing gauge transformation.
The theorem sharpens the statement, made after Proposition 6.1, that the recovery fibres are nonempty: on this realized branch a recovery witness is unique up to unique isomorphism, and
the realization neither adds nor removes symmetry; the reducible configurations, with nontrivial stabilizers, are exactly as reducible upstairs as downstairs. It does not classify other native antecedents of the same target; that question is addressed in the last subsection. The signed lattice permutations may be adjoined to both groupoids, since they act compatibly, (Section 9); the statement and its proof are unchanged.