IntheDistanceOracle problem,thegoalistopreprocess nvectorsx1,x2,...,xn in a d-dimensional metric space(Xd, l) into a cheap data structure, so that given a query vectorq Xd and a subsetS [n] of the input data points, all distances q xi l forxi S canbequicklyapproximated(fasterthanthetrivial d|S|querytime).

While standard recurrent neural networks explicitly impose achain structure on different forms of data, they do not have an explicit bias towards recursive selfinstantiation where the extent of recursion is dynamic.