Rake-Compress Riccati Recursions for Parallel Scenario-Tree Model Predictive Control

arXiv:2608.01332 2026 Architecture 1 ideas extracted · analyzed Aug 31, 2026

What the math gives to ML

The paper provides an exact rake–compress contraction for quadratic dynamic programs on arbitrary rooted trees, replacing the sequential tree-height dependency of Riccati/message-passing recursions with O(log N) span while preserving O(N) work. The transferable asset is not MPC-specific control, but the representation of a subtree by local quadratic value data and the use of Schur-complement eliminations as associative composition operations. A promising neural-network use is a differentiable Gaussian or quadratic latent tree layer whose upward and downward passes are contracted in parallel, enabling irregular hierarchical computation graphs without sequential depth proportional to tree height. This should be tested against ordinary sequential tree message passing for wall-clock latency, gradient correctness, and predictive quality at fixed work.

Ideas from this paper

✓✓ Beats tuned baseline 2026

Parallel Quadratic Tree Layer

Replace sequential upward message passing in a tree-structured neural module with rake–compress contraction of quadratic latent-state messages. Each node stores a quadratic value function and each edge stores a linear transition or coupling triple; leaf elimination and unary-node compression are implemented as batched Schur complements, followed by a reverse pass that reconstructs node latents and edge outputs. The layer is exact for Gaussian or quadratic latent models and remains…

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Paper: Rake-Compress Riccati Recursions for Parallel Scenario-Tree Model Predictive Control arXiv:2608.01332