  We consider the problem of designing locality sensitive hashes (LSH) for
inner product similarity, and of the power of asymmetric hashes in this
context. Shrivastava and Li argue that there is no symmetric LSH for the
problem and propose an asymmetric LSH based on different mappings for query and
database points. However, we show there does exist a simple symmetric LSH that
enjoys stronger guarantees and better empirical performance than the asymmetric
LSH they suggest. We also show a variant of the settings where asymmetry is
in-fact needed, but there a different asymmetric LSH is required.
