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arXiv 2604.04656cs.DScs.CC
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子集平衡与基于格的广义子集和

Subset Balancing and Generalized Subset Sum via Lattices

School of Cyber Science and Technology, University of Science and Technology of China(中国科学技术大学网络空间安全学院);Anhui Province Key Laboratory of Digital Security(安徽省数字安全重点实验室);KLMM, Academy of Mathematics and Systems Science, Chinese Academy of Sciences(中国科学院数学与系统科学研究院);School of Mathematical Sciences, University of Chinese Academy of Sciences(中国科学院大学数学科学学院);Hefei National Laboratory(合肥国家实验室)

Yiming Gao, Yansong Feng, Honggang Hu, Yanbin Pan

AI总结:

本文通过格理论将子集平衡问题与SVP_∞问题关联,提出基于格的算法在特定条件下实现更高效的求解,同时解决了广义子集和问题。

摘要:

我们研究了子集平衡问题:给定x∈Z^n和系数集C⊆Z,寻找非零向量c∈C^n使得c·x=0。标准的meet-in-the-middle算法运行时间为~O(|C|^{n/2}),而近期改进(SODA 2022, Chen, Jin, Randolph, and Servedio; STOC 2026, Randolph and Węgrzycki)超越这一障碍主要当d为常数时。我们给出一个将C={-d,…,d}的子集平衡问题减少到一个SVP_∞实例的减少,维度为n+1。将此减少应用于已知的最佳ℓ_∞-SVP算法,得到确定性的~O((6√2πe)^n)-时间算法和随机的~O(2^{2.443n})-时间算法。指数仅取决于n,优于meet-in-the-middle对于所有d≥15。对于足够大的d我们还获得多项式时间算法。该减少从盒约束[-d,d]^n扩展到任何中心对称凸体K⊆R^n,给出确定性时间~O(2^{c_K n}),其中c_K仅取决于K的形状。我们进一步研究了广义子集和问题,寻找c∈C^n使得c·x=τ。对于C={-d,…,d}或C={-d,…,d}\{0},我们将最坏情况问题减少到CVP_∞在维度n+1。我们观察到我们的格中的距离仅取整数值,因此近似CVP_∞ oracle仍然足够,得到一个确定性的最坏情况算法运行时间2^{O(n log log d)}。在平均情况设置下,我们证明对于两种系数集,嵌入的CVP_∞实例满足有界距离承诺,去除log log d因子,获得运行时间~O((18√2πe)^n)的确定性算法。

英文摘要:

We study the Subset Balancing problem: given $x \in \mathbb{Z}^n$ and a coefficient set $C \subseteq \mathbb{Z}$, find a nonzero vector $c \in C^n$ such that $c\cdot x = 0$. The standard meet-in-the-middle algorithm runs in time $\tilde{O}(|C|^{n/2})$, and recent improvements (SODA 2022, Chen, Jin, Randolph, and Servedio; STOC 2026, Randolph and Węgrzycki) beyond this barrier apply mainly when $d$ is constant. We give a reduction from Subset Balancing with $C = \{-d, \dots, d\}$ to a single instance of SVP$_{\infty}$ in dimension $n+1$. Instantiating this reduction with the best known $\ell_\infty$-SVP algorithms yields a deterministic $\tilde{O}((6\sqrt{2πe})^n)$-time algorithm and a randomized $\tilde{O}(2^{2.443n})$-time algorithm. The exponent depends only on $n$, improving on meet-in-the-middle for all $d\ge 15$. For sufficiently large $d$ we also obtain a polynomial-time algorithm. The reduction extends from the box constraint $[-d,d]^n$ to any centrally symmetric convex body $K\subseteq\mathbb{R}^n$, giving deterministic time $\tilde{O}(2^{c_K n})$ for a constant $c_K$ depending only on the shape of $K$. We further study the Generalized Subset Sum problem of finding $c \in C^n$ such that $c \cdot x = τ$. For $C = \{-d, \dots, d\}$ or $C = \{-d,\dots,d\}\setminus\{0\}$, we reduce the worst-case problem to CVP$_{\infty}$ in dimension $n+1$. We observe that distances in our lattice take only integer values, so an approximate CVP$_{\infty}$ oracle still suffices, yielding a deterministic worst-case algorithm running in time $2^{O(n\log\log d)}$. In the average-case setting, we demonstrate that for both coefficient sets the embedded CVP$_{\infty}$ instance satisfies a bounded-distance promise with high probability, removing the $\log\log d$ factor altogether and obtaining a deterministic algorithm running in time $\tilde{O}((18\sqrt{2πe})^n)$.

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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