pith. sign in
theorem

RCLCombiner_isCoupling_iff

proved
show as:

Why this theorem is linked from AoI-Aware Multi-Robot Sensing and Transport on Connected Graphs unclear

Pith linked this Lean declaration because the review connected a specific passage in the paper to this theorem. The relation tag says how strong that connection is; it is not a generic placeholder.

greedy water-filling algorithm that assigns robots according to marginal AoI reduction attains an optimal allocation (separable discretely convex problem)

Relation between the paper passage and the cited Recognition theorem.

module
IndisputableMonolith.Foundation.BranchSelection
domain
Foundation
line
145 · github
papers citing
68 papers (below)

plain-language theorem explainer

The equivalence shows that the RCL polynomial combiner with parameter c is a coupling combiner precisely when c is nonzero. Branch-selection arguments in the Recognition framework cite it to exclude the additive branch of the composition-law family. The proof rewrites the coupling predicate through the interaction-defect characterization and dispatches both directions by substitution plus a test-point evaluation.

Claim. Let $P_c(u,v) := 2u + 2v + c uv$. A combiner $P$ is coupling when it is not separately additive. Then $P_c$ is coupling if and only if $c ≠ 0$.

background

The Recognition Composition Law family is $F(xy) + F(x/y) = 2F(x) + 2F(y) + c F(x)F(y)$, realized by the polynomial combiner $P(u,v) = 2u + 2v + c uv$. The module distinguishes the bilinear branch ($c ≠ 0$, representative $J(x) = ½(x + x^{-1}) - 1$) from the additive branch ($c = 0$, representative ½(ln x)²). The strengthened (L4*) requires the combiner to be coupling rather than separately additive, which forces the bilinear branch.

proof idea

The proof rewrites the statement with isCouplingCombiner_iff_interactionDefect_nonzero. The forward direction assumes a pair with nonzero defect, supposes c = 0 for contradiction, substitutes the defect formula interactionDefect_RCLCombiner and obtains zero by ring. The reverse direction applies RCLCombiner_nonzero_couples at the test point (1,1) to exhibit a nonzero defect.

why it matters

This supplies the central equivalence for the downstream branch_selection theorem, which is the Lean rendering of the branch-selection result in RS_Branch_Selection.tex. It isolates the bilinear representative J of the RCL family, aligning with the J-uniqueness step (T5) of the forcing chain and the Recognition Composition Law. Residual α-coordinate freedom is deferred to separate calibration conditions outside this operator-level statement.

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