Replace the final nonlinear transition network of a latent world model with a linear Koopman-style transition whose coefficients have a Matrix Normal-Inverse Wishart prior. Meta-learn the prior across tasks, then adapt only closed-form sufficient statistics from a few recent transitions; this should be more data-efficient and uncertainty-aware than gradient fine-tuning under distribution shift.
Replace a neural network head that predicts a covariance or other SPD matrix entrywise with regression in the matrix-log domain. The network predicts a symmetric matrix in unconstrained Euclidean coordinates, the matrix exponential guarantees an SPD output, and training can use intrinsic log-Euclidean or affine-invariant errors rather than Frobenius error on raw entries.