Abstract

Abstract: In this work, we establish the first separation between computation with bounded and unbounded space, for problems with short outputs (i.e., working memory can be exponentially larger than output size), both in the classical and the quantum setting. Towards that, we introduce a problem called nested collision finding, and show that optimal query complexity can not be achieved without exponential memory. Our result is based on a novel two-oracle recording technique, where one oracle records the computation's long outputs under the other oracle, effectively reducing the time-space trade-off for short-output problems to that of long-output problems. We believe this technique will be of independent interest for establishing time-space tradeoffs in other short-output settings.

Time

Tuesday,  Sept.1, 15:30-16:30

Speaker

Zikuan Huang  is an incoming PhD student at the University of Cambridge. He obtained his B.E degree from Yao class,Tsinghua University. His main research area is quantum cryptography and quantum complexity theory.

Room

Room 104