Unverified
2026
Local Irreducible-Vertex Preconditioner
Use the paper’s observation that the fully irreducible vertex is approximately local after crossed-channel ladders are removed to build a block-local curvature correction for neural-network optimization. Estimate a cheap bare covariance and subtract the inverse full covariance to obtain a local irreducible correction, avoiding a dense four-point model while retaining interaction effects that ordinary diagonal preconditioners miss.
Paper: The two-particle-irreducible vertex of the two-dimensional lattice $φ^4$ model across the Ising transition
arXiv:2608.04497