Foundational Analysis Of The Solvability Complexity Index: The Weihrauch-SCI Intermediate Hierarchy

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Auteur principal: Sorg, Christopher
Format: Preprint
Publié: 2026
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_version_ 1866918501462048768
author Sorg, Christopher
author_facet Sorg, Christopher
contents The Solvability Complexity Index (SCI) provides an extensional limit-height formalism for recovering a target map $Ξ$ from finite samples of an evaluation interface $Λ\subseteq\mathbb C^Ω$ by finite-height towers of pointwise limits. We first give a foundational analysis of what this extensional framework does and does not determine. We show that the SCI separation axiom is equivalent to a factorization of $Ξ$ through the full evaluation table, and we isolate the minimal logical role of $Λ$ as an information interface. To connect the SCI to Type-2 computability and Weihrauch reducibility, we give an effective enrichment for countable $Λ$ by viewing the evaluation table image $I_Λ\subseteq\mathbb{C}^{\mathbb{N}}$ as a represented space and factoring $Ξ$ as $\widehatΞ$. We then define the Weihrauch-SCI rank of a problem as the least number of iterated limit-oracles needed to compute it in the Weihrauch sense, i.e.\ the least $k$ such that $\widehatΞ\le_{W}\lim^{(k)}$, and prove well-posedness and representation invariance of this rank. A central negative result is that the unrestricted raw type-G SCI model (arbitrary post-processing of finite oracle transcripts) is generally not a computability model in the Type-2/Weihrauch sense. To recover a robust bridge, we introduce an intermediate SCI hierarchy by restricting the admissible base-level post-processing to regularity classes (continuous/Borel/Baire) and, optionally, to fixed-query versus adaptive-query policies. We prove that these restrictions form hierarchies, and we establish comparison theorems showing what each restriction logically enforces.
format Preprint
id arxiv_https___arxiv_org_abs_2603_18955
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Foundational Analysis Of The Solvability Complexity Index: The Weihrauch-SCI Intermediate Hierarchy
Sorg, Christopher
Logic
Logic in Computer Science
Spectral Theory
03D78, 03D30, 03D55, 03E15, 68Q17, 54C35
The Solvability Complexity Index (SCI) provides an extensional limit-height formalism for recovering a target map $Ξ$ from finite samples of an evaluation interface $Λ\subseteq\mathbb C^Ω$ by finite-height towers of pointwise limits. We first give a foundational analysis of what this extensional framework does and does not determine. We show that the SCI separation axiom is equivalent to a factorization of $Ξ$ through the full evaluation table, and we isolate the minimal logical role of $Λ$ as an information interface. To connect the SCI to Type-2 computability and Weihrauch reducibility, we give an effective enrichment for countable $Λ$ by viewing the evaluation table image $I_Λ\subseteq\mathbb{C}^{\mathbb{N}}$ as a represented space and factoring $Ξ$ as $\widehatΞ$. We then define the Weihrauch-SCI rank of a problem as the least number of iterated limit-oracles needed to compute it in the Weihrauch sense, i.e.\ the least $k$ such that $\widehatΞ\le_{W}\lim^{(k)}$, and prove well-posedness and representation invariance of this rank. A central negative result is that the unrestricted raw type-G SCI model (arbitrary post-processing of finite oracle transcripts) is generally not a computability model in the Type-2/Weihrauch sense. To recover a robust bridge, we introduce an intermediate SCI hierarchy by restricting the admissible base-level post-processing to regularity classes (continuous/Borel/Baire) and, optionally, to fixed-query versus adaptive-query policies. We prove that these restrictions form hierarchies, and we establish comparison theorems showing what each restriction logically enforces.
title Foundational Analysis Of The Solvability Complexity Index: The Weihrauch-SCI Intermediate Hierarchy
topic Logic
Logic in Computer Science
Spectral Theory
03D78, 03D30, 03D55, 03E15, 68Q17, 54C35
url https://arxiv.org/abs/2603.18955