We study the communication complexity of multiplying k\times t
elements from the group H=\text{SL}(2,q) in the number-on-forehead
model with k parties. We prove a lower bound of (t\log H)/c^{k}.
This is an exponential improvement over previous work, and matches
the state-of-the-art in the area.

Relatedly, we show that the convolution ... more >>>