The direct sum of universal relations

In this paper, we prove a direct sum theorem for the universal relation, namely, we prove that solving m independent instances of the universal relation is m times harder than solving a single instance. More specifically, it is known that the deterministic communication complexity of the universal relation is at least n. We prove that the deterministic communication complexity of solving m independent instances of the universal relation is at least m⋅(n−O(log⁡m)).