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Abstract
Financial institutions deploy machine-learning models for high-stakes
credit decisions, but deployed systems routinely fail to satisfy the joint
requirements of explainability, auditability, and operational performance
imposed by regulatory risk management frameworks. Counterfactual explanations
align with legal notions of contestability, yet existing generators are
expensive, unstable, and produce artifacts that are not independently
verifiable. This paper presents an empirically evaluated governance-oriented
architecture that integrates (i) a quantum-inspired evolutionary algorithm for
counterfactual search (QIEA-CF), (ii) a sensitivity-based local linear model
for interpretable explanation, and (iii) a blockchain-based provenance layer
that commits versioned hashes via Merkle-batched anchoring. The architecture is
evaluated on the FICO HELOC dataset (10,459 applications, 23 features) against
three baselines across eight metrics. QIEA-CF achieves 96.7% validity with mean
L1 proximity 2.418 and sparsity 6.8, outperforming the best baseline by 3.3
percentage points while reducing generation time from 1,847 ms to 198 ms per
explanation. Batched Solana anchoring delivers a per-decision cost of US$9.75 ×
10⁻⁷ at batch size 1,000 and a median verification latency of 47.9 ms. Results
show that legally meaningful counterfactual explanation and cryptographically
verifiable provenance are deliverable with sub-cent marginal cost and sub-250
ms latency.
JEL classification numbers: C45,
C61, G21, G28, K24, O33.
Keywords:
Explainable artificial intelligence, Counterfactual
explanation, Quantum-inspired optimization, Blockchain provenance, AI
governance, Credit underwriting.