Repairability of Inexact Solvers in Recursive State Estimation with Machine Learning
A certified repair framework evaluates inexact and quantum linear solvers inside Kalman estimation, including a power-grid study.
The paper analyzes when a bounded subspace correction can satisfy a local admissibility tolerance inside a linear Kalman estimator and how solver defects affect finite-horizon covariance. It separates current solve error from inherited gain drift and identifies opposing quartic contributions that can produce quadratic under- or overprediction. Learned corrections remain governed by a learner-independent residual certificate and fallback. In a power-grid study, learned correction reduced the conjugate-gradient iterations required for certified deployment, and variational and annealing quantum solvers were executed through the same interface.
- Bounded corrections are certified against a local Kalman admissibility tolerance.
- Learned fixes reduced conjugate-gradient iterations in a power-grid study.
- Quantum variational and annealing solvers used the same certified interface.
- Opposing quartic terms can cause quadratic covariance under- or overprediction.
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Recursive state estimation often executes approximate numerical solutions inside a feedback loop, where highly accurate local steps do not guarantee better overall results. For a fixed linear Kalman model, we characterize when a correction within a prescribed subspace and norm budget can meet a local admissibility tolerance, and how the defects actually executed affect the finite-horizon covariance response. Centering each defect on the exact gain for the implemented covariance separates current solve error from inherited gain drift. Expanding the exact residual-drift identity reveals opposing quartic contributions beyond the quadratic response: innovation-covariance inflation enters positively, while local-gain reoptimization enters subtractively. Under matched initialization, an absolute sixth-order remainder bound, uniform over bounded defect sequences at fixed horizon, gives sufficient conditions for quadratic under- or overprediction. Machine learning proposes bounded corrections, while a learner-independent residual certificate and verified fallback govern execution of classical and quantum candidates without changing the reference estimator. In a power-grid tolerance study, learned correction lowers the minimum conjugate-gradient iteration count for deployment without fallback relative to uncorrected solves under the same residual certificate. Gains reconstructed from a variational quantum linear solver and from an annealing-based binary encoding, with small-scale terminal measurements on superconducting hardware and sampling on a quantum annealer, are executed through the same interface. By linking local repairability to nonlinear error propagation, the framework evaluates approximate solvers and learned corrections through independent certification and finite-horizon response, providing a practical basis for studying hybrid quantum--classical computation.
Text extracted automatically; images, tables and formatting may be missing. Original: https://arxiv.org/abs/2609.28425