An outstanding open problem asks if there exists a boolean matrix with unbounded sign-rank, but bounded randomised communication complexity. We make progress towards this question by proving lower bounds against real linear sketches (a model weaker than sign-rank): Alice and Bob send few linear measurements to a referee, who makes ... more >>>

We prove that the sign-rank of the $k$-Hamming Distance matrix on $n$ bits is $2^{O(k)}$, independent of the number of bits $n$. This strongly refutes the conjecture of Hatami, Hatami, Pires, Tao, and Zhao (RANDOM 2022), and Hatami, Hosseini, and Meng (STOC 2023), repeated in several other papers, that the ... more >>>