Turn an iterative optimization or equilibrium computation inside a neural network into a differentiable layer whose backward pass solves the implicit adjoint system with conjugate gradients or GMRES using only automatic-differentiation matrix-vector products. This avoids storing unrolled iterations and avoids explicit Hessian or Jacobian construction, enabling longer solver horizons and lower-memory implicit architectures.
Train a neural trial function for an elliptic PDE using a very-weak residual in which all derivatives act on fixed smooth test functions rather than on the neural network. This eliminates second-order reverse-mode or forward-mode automatic differentiation and allows low-regularity activations while retaining a least-squares objective over many test functions.
Replace uniform collocation for a fixed random-feature neural PDE solver with sampling from the leverage-score density of the operator-applied features. Whiten the retained residual feature space before solving for output coefficients, so the sampled least-squares matrix has an identity-like expected Gram rather than inheriting severe anisotropy from the differential operator. The same construction can be used for a linearized neural network by treating Jacobian features as the trial functions.
Train a neural network to represent an elliptic solution using Walk-on-Spheres rollouts as stochastic targets instead of evaluating a mesh-based PDE residual. For each input point, recursively jump to a random point on the largest interior sphere, accumulate source contributions, evaluate boundary data at termination, and regress the network output to the resulting Monte Carlo estimate.
Train a frozen-feature or linearized neural network by residual least squares on deterministic quasi-uniform points rather than independently sampled collocation points. The paper's norm-equivalence result predicts that, once the number of residual points is proportional to the number of active features, the empirical residual controls the continuous residual and avoids random undersampling of localized errors.