SpatialRNN replaces direct neuron-to-neuron links with a PDE medium, holding near-100% copy-task accuracy with 6.8k parameters while HORNNs degrade to about 13%
The authors introduce SpatialRNN, in which recurrent neuron-to-neuron communication is replaced by a spatially evolving medium governed by discretized PDEs, and prove that the medium state equals a convolution over the entire history of hidden states, i.e. a structured infinite-order RNN with a fixed parameter count; constructive conditions confine gradient modes to circles of prescribed radii, yielding better long-horizon performance than other recurrent models with fewer parameters.