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LeanPool.PointwiseComposition.CategoricalRiceShapiro.PartialRecursive.CanonicalComposition

Supporting results for pointwise provable equality.

The canonical index of a composed partial-recursive program #

canonicalPartrecCompIndex f g is the Mathlib index of Nat.Partrec.Code.comp applied to the programs those two indices name. Its constructor number is 5 and its two subcodes are the given indices, which the three theorems below record. Each rests on the same closed form,

canonicalPartrecCompIndex f g = 2 * (2 * Nat.pair f g + 1) + 4,

proved once in canonicalPartrecCompIndex_eq.

The evaluation results then read those numbers off inside an arbitrary model of 𝐏𝐀⁻: a code whose graph holds at the canonical index has, at the same assignment, the graph of the constructor number at 5 and of the two subcodes at fCode and gCode.

The index of the composition of the programs named by fCode and gCode.

Equations
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Instances For

    The closed form of the canonical composition index.

    The outer subindex is below the canonical composition index.

    The inner subindex is below the canonical composition index.

    The payload of the canonical composition index is the pair of subindices.

    The first subcode of the canonical composition index is the outer one.

    The second subcode of the canonical composition index is the inner one.

    Evaluation in an arbitrary model #

    The constructor number of the canonical composition index, read inside a model: it is 5, the number of composition.