IsNormalized
plain-language theorem explainer
A cost function F is normalized precisely when F(1) equals zero. Researchers proving T5 uniqueness of the J-cost under composition and calibration cite this predicate as the zero-point anchor. The declaration is a direct one-line definition that supplies the base hypothesis for downstream Aczél and cost-algebra results.
Claim. Let $F : (0,∞) → ℝ$. The function $F$ is normalized when $F(1) = 0$.
background
The Cost.FunctionalEquation module supplies lemmas for the T5 cost uniqueness proof. Normalization fixes the zero of the cost at unit scale and pairs with the reparametrization $G(t) := F(e^t)$ together with the Calibration axiom requiring $G''(0) = 1$. Upstream, DAlembert.Inevitability supplies the identical predicate while CostAxioms.Calibration states that the second derivative at the origin equals 1, ensuring a unique solution rather than a family.
proof idea
This is a one-line definition that directly encodes the predicate $F(1) = 0$. No lemmas or tactics are applied; the declaration serves as the base predicate for results such as H_one_of_normalized and the uniqueness theorems in CostAlgebra.
why it matters
The definition supplies the normalization hypothesis required by the parent theorems cost_algebra_unique and cost_algebra_unique_aczel, which establish that any cost satisfying the composition law, reciprocity, and calibration must coincide with the J function. It corresponds to the first calibration step in T5 J-uniqueness of the forcing chain and touches the question of minimal regularity needed to force the self-similar fixed point.
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