内容：
We show that every language in PSPACE that is decidable by a Turing machine in time T(n)=n^{O(log n)} admits a doubly efficient interactive proof system: the prover runs in time polynomial in T(n), and the verifier runs in time polynomial in n. This extends the best previously known regime for such proof systems from T(n)=n^{O(sqrt{log n / loglog n})}, established by Berger, Goyal, Hong, and Kalai (FOCS 2025), to T(n)=n^{O(log n)}.
Beyond improving the range of T, our protocol is substantially simpler than previous doubly efficient proofs for time-bounded PSPACE. Earlier constructions proceed indirectly: they first build batch interactive proofs and then invoke them as a black box to obtain doubly efficient protocols. In contrast, we give a direct construction. This not only simplifies the proof but also points to a more promising route for future improvements.
Based on joint work with Liyan Chen, Yael Tauman Kalai, and Zoe Xi [arXiv:2606.21799].
