The disjoint-union factorization of the corrected value #
The corrected constrained partition value of a disjoint union at a
boundary state factors as the product of the componentwise values
at the restricted states, with the lexicographic label order on
the union. This part supplies the subset and transition-system
half; B.lean splits the colourings and the summand, and C.lean
migrates canonical data.
The route reindexes the Eulerian subset sum along the
componentwise splitting of DisjSubsetSplit, restricts and
multiplies boundary-relative transition systems componentwise,
adds circuit counts (each component's orbit data is even: the
edge-pairing reversal is a fixed-point-free involution on walk
orbits), and splits the through product and the colouring sums.
Membership characterizations (any fragment) #
Attachment over the union (mirrors DisjSubsetSplit) #
A left flag is internally attached in the union exactly when it is internally attached in the left component.
A right flag is internally attached in the union exactly when it is internally attached in the right component.
The component edge subsets #
The left component of an edge subset of a disjoint union.
Equations
- RS.leftSub F = { flags := RS.leftPart F.flags, pairing_mem := ⋯ }
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The right component of an edge subset of a disjoint union.
Equations
- RS.rightSub F = { flags := RS.rightPart F.flags, pairing_mem := ⋯ }
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Internality is componentwise on the left.
Internality is componentwise on the right.
Parity of the open orbit data #
The edge pairing reverses walk orbits: it is a fixed-point-free
involution of the periodic flags conjugating the walk permutation
to its inverse. Consequently both the nontrivial cycles and the
fixed points of the walk permutation pair up, and the orbit total
entering openCircuitCount is even.
Componentwise relative transition systems #
Restriction to the components #
Restrict a union matching to a left flag, fixing it if the image lies on the right.
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Restrict a union matching to a right flag, fixing it if the image lies on the left.
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On an internal left flag, the union system's match is the left descent, injected.
On an internal right flag, the union system's match is the right descent, injected.
The left descent of an internal left flag is again internal.
The right descent of an internal right flag is again internal.
The restriction of a transition system on the union to its left component: the matching never crosses between components, so it restricts.
Equations
- RS.leftRel κ = { match_ := RS.leftDescend κ, match_invol := ⋯, match_ne := ⋯, match_mem := ⋯, match_vertex := ⋯ }
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The restriction to the right component.
Equations
- RS.rightRel κ = { match_ := RS.rightDescend κ, match_invol := ⋯, match_ne := ⋯, match_mem := ⋯, match_vertex := ⋯ }
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The product system #
The product of two componentwise transition systems: a system on the union, inverse to the two restrictions.
Equations
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The product of two componentwise orientations.
Equations
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Circuit count additivity #
A walk of the product system started at a left flag stays left and tracks the left component's walk.
The right analogue.
A left flag is periodic for the product system exactly when it is periodic for the left factor: the walk never crosses components.
A right flag is periodic for the product system exactly when it is periodic for the right factor.
The product system's periodic flags are the disjoint sum of the two factors' periodic flags.
Equations
- One or more equations did not get rendered due to their size.
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Under that identification the product system's walk permutation is the sum of the two factors' walk permutations.
Circuit counts add: the product system's open circuit count is the sum of the two components'. Each component's orbit data is even, so no halving correction survives the split.