Cell-probe lower bounds for the partial match problem

T. S. Jayram, Subhash Khot, Ravi Kumar, Yuval Rabani

Abstract: Given a database of n points in (0,1)d, the partial match problem is: In response to a query x in (0, 1, *)d, find a database point y such that for every i whenever xi ≠ *, we have xi = yi. In this paper we show randomized lower bounds in the cell-probe model for this well-studied problem[18, 11, 19, 16, 4, 6 ].Our lower bounds follow from a two-party asymmetric randomized communication complexity near-optimal lower bound for this problem, where we show that either Alice has to send Ω(d log n) bits or Bob has to send Ω(n1 - o(1)) bits. When applied to the cell-probe model, it means that if the number of cells is restricted to be poly(n, d) where each cell is of size poly(log n, d), then Ω(d/log2 n) probes are needed. This is an exponential improvement over the previously known lower bounds for this problem[16, 4].