New Space Lower-Bound Techniques for Streaming Algorithms
A recent result of Li, Nguyen, and Woodruff shows that for any streaming algorithm in the turnstile model (where the stream consists of insertions and deletions of elements) there exists an algorithm that works by only maintaining a linear sketch and uses only slightly more space. So to prove a space lower bound in the turnstile model it is (up to some logarithmic factors) enough to prove a space lower bound for linear sketches. These can be easier to prove, for example by proving a communication lower bound in the simultaneous communication model rather than in the one-way model, or by more directly working with the linear structure of the sketch: check the paper for a lower bound on the space complexity of frequency moments proved this way.