Some Results on Activation and Scaling of Sparse Distributed Memory

It has been suggested that in certain situations it would make sense to use different activation probabilities for writing and reading in SDM (Sparse Distributed Memory). However, here we model such a situation and find that, at least approximately, it is optimal to use the same probabilities for writing and reading. We also investigate the scaling up of SDM, in connection with some observations made by Sjödin, see \cite{Sjodin-97}. It is shown that the original SDM (here in Jaeckel's version) does not scale up if the reading address is disturbed, but that this can be remedied by using a kind of sparse SDM