arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2602.14320cs.DS
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从匹配向量评估催化树

Catalytic Tree Evaluation From Matching Vectors

MIT(麻省理工学院)

Alexandra Henzinger, Edward Pyne, Seyoon Ragavan

AI总结:

本文提出了一种改进的催化树评估算法,实现了亚多项式催化空间和多项式时间,为将树评估放入logspace提供了新方法。

摘要:

我们为树评估(S. Cook等人,TOCT 2012)在催化计算模型(Buhrman等人,STOC 2014)中给出了新的算法。两种现有方法旨在以低空间解决树评估:一方面,J. Cook和Mertz(STOC 2024)给出了一个树评估算法,其空间为超对数空间$O(\log n\log\log n)$,时间超多项式$ n^{O(\log\log n)} $。另一方面,通过将树评估简化为电路评估,并结合Buhrman等人(STOC 2014)的结果,给出了一个树评估的催化算法,其空间为对数$O(\log n)$自由空间,时间多项式,但催化空间为多项式。我们证明后者结果可以改进。我们给出了一个树评估的催化算法,其自由空间为对数$O(\log n)$,时间多项式,催化空间为亚多项式$2^{\log^εn}$(对于任何$ε> 0$)。我们的结果为将树评估放入logspace开辟了新思路,并立即通过Williams(STOC 2025)的简化,实现了时间的改进模拟。我们的催化树评估算法受到与匹配向量族和私人信息检索的联系的启发,改进的(均匀)匹配向量族构造将导致算法的改进。

英文摘要:

We give new algorithms for tree evaluation (S. Cook et al. TOCT 2012) in the catalytic-computing model (Buhrman et al. STOC 2014). Two existing approaches aim to solve tree evaluation (TreeEval) in low space: on the one hand, J. Cook and Mertz (STOC 2024) give an algorithm for TreeEval running in super-logarithmic space $O(\log n\log\log n)$ and super-polynomial time $n^{O(\log\log n)}$. On the other hand, an earlier algorithm of J. Cook and Mertz (STOC 2020), run on a catalytic tape, solves TreeEval in logarithmic $O(\log n)$ free space and polynomial time, but with polynomial $O(\sqrt{n})$ catalytic space. We show that the latter result can be improved. We give a catalytic algorithm for TreeEval with logarithmic $O(\log n)$ free space, polynomial runtime, and subpolynomial $2^{O(\log^εn)}$ catalytic space (for any $ε> 0$). Our result also implies an improved simulation of time by catalytic space, via the reduction of Williams (STOC 2025). Our TreeEval algorithm comes from a framework, inspired by private information retrieval, that generically reduces tree evaluation to two combinatorial objects: matching-vector families and decoders (a new object we define that closely resembles decoding polynomials). These ingredients' parameters directly govern an algorithm's resources: the vectors' dimension determines its catalytic space, and the decoder's sparsity determines its free space and runtime. In addition to enabling our new algorithm, this framework explains existing tradeoffs, for example why the Cook-Mertz algorithm needs super-logarithmic space but no catalytic tape. It also lets better matching-vector families or decoders plug in directly to give better algorithms.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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