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arXiv 2305.03037cs.LO
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带幂或幂运算的Presburger算术的复杂性

The complexity of Presburger arithmetic with power or powers

University of Oxford(牛津大学);University of Warwick(华威大学);IMDEA Software Institute(IMDEA软件研究所)

Michael Benedikt, Dmitry Chistikov, Alessio Mansutti

AI总结:

研究带指数运算的Presburger算术的复杂性,证明PresPower理论可在三指数时间内判定,PresExp存在片段有NExpTime上界。

摘要:

我们研究了Presburger算术的扩张,即整数加法与序理论,加上与指数运算相关的额外结构:要么是取一个数的2的幂的函数,要么是2的幂的谓词。后一个理论,记为$\mathrm{PresPower}$,由Büchi引入,作为首次尝试刻画可用有限自动机表示的数元组集合;Büchi的方法没有给出初等上界,且该理论的复杂性一直是开放的。前一个理论,记为$\mathrm{PresExp}$,由Semenov证明可判定;虽然该理论的判定过程与Büchi提出的基于自动机的方法截然不同,但Semenov的方法也是非初等的。事实上,带幂函数的理论具有非初等下界。在本文中,我们表明,虽然Semenov和Büchi的方法对$\mathrm{PresPower}$导致非初等爆炸,但该理论实际上可在三指数时间内判定,类似于Presburger算术最知名的量词消去算法。我们还为$\mathrm{PresExp}$的存在片段提供了$\mathrm{NExpTime}$上界,这是向更精细复杂性分析迈出的一步。这两个结果都是通过分析$\mathrm{PresExp}$的一个参数化可满足性算法建立的,该算法可以专门用于$\mathrm{PresPower}$或$\mathrm{PresExp}$的存在理论。除了$\mathrm{PresExp}$和$\mathrm{PresPower}$存在理论的新上界外,我们相信我们的算法为这些理论的可判定性以及导致非初等爆炸的特征提供了新的直觉。

英文摘要:

We investigate expansions of Presburger arithmetic, i.e., the theory of the integers with addition and order, with additional structure related to exponentiation: either a function that takes a number to the power of $2$, or a predicate for the powers of $2$. The latter theory, denoted $\mathrm{PresPower}$, was introduced by Büchi as a first attempt at characterizing the sets of tuples of numbers that can be expressed using finite automata; Büchi's method does not give an elementary upper bound, and the complexity of this theory has been open. The former theory, denoted as $\mathrm{PresExp}$, was shown decidable by Semenov; while the decision procedure for this theory differs radically from the automata-based method proposed by Büchi, Semenov's method is also non-elementary. And in fact, the theory with the power function has a non-elementary lower bound. In this paper, we show that while Semenov's and Büchi's approaches yield non-elementary blow-ups for $\mathrm{PresPower}$, the theory is in fact decidable in triply exponential time, similarly to the best known quantifier-elimination algorithm for Presburger arithmetic. We also provide a $\mathrm{NExpTime}$ upper bound for the existential fragment of $\mathrm{PresExp}$, a step towards a finer-grained analysis of its complexity. Both these results are established by analyzing a single parameterized satisfiability algorithm for $\mathrm{PresExp}$, which can be specialized to either the setting of $\mathrm{PresPower}$ or the existential theory of $\mathrm{PresExp}$. Besides the new upper bounds for the existential theory of $\mathrm{PresExp}$ and $\mathrm{PresPower}$, we believe our algorithm provides new intuition for the decidability of these theories, and for the features that lead to non-elementary blow-ups.

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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