We present a way to create small yet difficult model counting instances. Our generator is highly parameterizable: the number of variables of the instances it produces, as well as their number of clauses and the number of literals in each clause, can all be set to any value. Our instances have been tested on state of the art model counters, against other difficult model counting instances, in the Model Counting Competition. The smallest unsolved instances of the competition, both in terms of number of variables and number of clauses, were ours. We also observe a peak of difficulty when fixing the number of variables and varying the number of clauses, in both random instances and instances built by our generator. Using these results, we predict the parameter values for which the hardest to count instances will occur.

冲突驱动的子句学习（CDCL）是解决命题逻辑令人满意问题的非常成功的范式。这种求解器不是简单的深度优先回溯方法，而是以其他条款的形式了解了发生冲突的原因。但是，尽管CDCL求解器取得了巨大的成功，但仍然对以什么方式影响这些求解器的性能有限。考虑到不同的措施，本文非常令人惊讶地证明，从句学习（不摆脱某些条款）不仅可以帮助求解器，而且可能会大大恶化解决方案过程。通过进行广泛的经验分析，我们进一步发现，CDCL求解器的运行时分布是多模式的。这种多模式可以看作是上面描述的恶化现象的原因。同时，这也表明了为什么从条款删除结合条款学习的原因实际上是SAT解决的事实标准，尽管存在这种现象。作为最终贡献，我们表明Weibull混合物分布可以准确描述多模式分布。因此，在基本实例中添加新的子句具有长期运行时间的固有效果。该洞察力提供了一个解释，即为什么忘记条款的技术在CDCL求解器中有用，除了单位传播速度的优化。

命题模型计数或#SAT是计算布尔公式满足分配数量的问题。来自不同应用领域的许多问题，包括许多离散的概率推理问题，可以将#SAT求解器解决的模型计数问题转化为模型计数问题。但是，确切的#sat求解器通常无法扩展到工业规模实例。在本文中，我们提出了Neuro＃，这是一种学习分支启发式方法，以提高特定问题家族中的实例的精确#sat求解器的性能。我们通过实验表明，我们的方法减少了类似分布的持有实例的步骤，并将其推广到同一问题家族的更大实例。它能够在具有截然不同的结构的许多不同问题家族上实现这些结果。除了步骤计数的改进外，Neuro＃还可以在某些问题家族的较大实例上在较大的实例上实现壁式锁定速度的订单，尽管开头查询了模型。

大多数-AT是确定联合正常形式（CNF）中输入$ N $的最低价公式的问题至少为2 ^ {n-1} $令人满意的作业。在对概率规划和推论复杂性的各种AI社区中，广泛研究了多数饱和问题。虽然大多数饱满为期40多年来，但自然变体的复杂性保持开放：大多数 - $ k $ SAT，其中输入CNF公式仅限于最多$ k $的子句宽度。我们证明，每辆$ k $，大多数 - $ k $ sat是在p的。事实上，对于任何正整数$ k $和ratic $ \ rho \ in（0,1）$ in（0,1）$与有界分比者，我们给出了算法这可以确定给定的$ k $ -cnf是否至少有$ \ rho \ cdot 2 ^ n $令人满意的分配，在确定性线性时间（而先前的最着名的算法在指数时间中运行）。我们的算法对计算复杂性和推理的复杂性具有有趣的积极影响，显着降低了相关问题的已知复杂性，例如E-Maj-$ K $ Sat和Maj-Maj- $ K $ Sat。在我们的方法中，通过提取在$ k $ -cnf的相应设置系统中发现的向日葵，可以通过提取向日葵来解决阈值计数问题的有效方法。我们还表明，大多数 - $ k $ sat的易腐烂性有些脆弱。对于密切相关的gtmajority-sat问题（我们询问给定公式是否超过2 ^ {n-1} $满足分配），这已知是pp-cleanting的，我们表明gtmajority-$ k $ sat在p for $ k \ le 3 $，但为$ k \ geq 4 $完成np-cleante。这些结果是违反直觉的，因为这些问题的“自然”分类将是PP完整性，因为GTMAJority的复杂性存在显着差异 - $ k $ SAT和MOSTION- $ K $ SAT为所有$ k \ ge 4 $。

优化在离散变量上的高度复杂的成本/能源功能是不同科学学科和行业的许多公开问题的核心。一个主要障碍是在硬实例中的某些变量子集之间的出现，导致临界减慢或集体冻结了已知的随机本地搜索策略。通常需要指数计算工作来解冻这种变量，并探索配置空间的其他看不见的区域。在这里，我们通过开发自适应梯度的策略来介绍一个量子启发的非本球非识别蒙特卡罗（NMC）算法，可以有效地学习成本函数的关键实例的几何特征。该信息随行使用，以构造空间不均匀的热波动，用于以各种长度尺度集体未填充变量，规避昂贵的勘探与开发权衡。我们将算法应用于两个最具挑战性的组合优化问题：随机k可满足（K-SAT）附近计算阶段转换和二次分配问题（QAP）。我们在专业的确定性求解器和通用随机求解器上观察到显着的加速和鲁棒性。特别是，对于90％的随机4-SAT实例，我们发现了最佳专用确定性算法无法访问的解决方案，该算法（SP）具有最强的10％实例的解决方案质量的大小提高。我们还通过最先进的通用随机求解器（APT）显示出在最先进的通用随机求解器（APT）上的时间到溶液的两个数量级改善。

We present the Neural Satisfiability Network (NSNet), a general neural framework that models satisfiability problems as probabilistic inference and meanwhile exhibits proper explainability. Inspired by the Belief Propagation (BP), NSNet uses a novel graph neural network (GNN) to parameterize BP in the latent space, where its hidden representations maintain the same probabilistic interpretation as BP. NSNet can be flexibly configured to solve both SAT and #SAT problems by applying different learning objectives. For SAT, instead of directly predicting a satisfying assignment, NSNet performs marginal inference among all satisfying solutions, which we empirically find is more feasible for neural networks to learn. With the estimated marginals, a satisfying assignment can be efficiently generated by rounding and executing a stochastic local search. For #SAT, NSNet performs approximate model counting by learning the Bethe approximation of the partition function. Our evaluations show that NSNet achieves competitive results in terms of inference accuracy and time efficiency on multiple SAT and #SAT datasets.

为了在难以解决布尔可满足问题实例的同时对多线程模式进行多线程模式的不确定终止行为，在难以解决布尔满足性问题实例，已收集和分析内部求解器运行时参数。已经选择了这些参数的子集，并使用作为特征向量，以成功创建一个机器学习模型，以便使用尚未解决的实例的任何新的解决操作来成功为求解程序终止行为的二进制分类创建机器学习模型。该模型可用于早期估计解决唯一的尝试或不属于候选人的候选人，以便快速终止。在这种情况下，运行时特征的主动简介的组合似乎镜像求解器瞬间启发式的影响，以了解解决者解决程序的立即质量。由于已经前两个解决迭代的运行时参数足以预测尝试良好成功分数的终止，所以当前工作的结果提供了有希望的基础，这可以进一步发展，以便丰富加密或通常具有现代卫星的加密AI能力。

部分MaxSAT（PMS）和加权部分MaxSAT（WPMS）都是MaxSAT典型组合问题的实用概括。在这项工作中，我们提出了一种有效的远视概率采样的基于本地搜索算法，称为FPS，用于解决这两个问题，表示为（W）PMS。 FPS算法替换了每个迭代步骤翻转单个变量的机制，该步骤广泛用于拟议的远视本地搜索策略，并提供更高质量的本地最佳解决方案。远视策略采用概率采样技术，允许该算法广泛有效地寻找。以这种方式，FPS可以提供​​更多更好的搜索方向并提高性能而不降低效率。关于最近四年的MaxSAT评估的不完整轨迹的所有基准的广泛实验表明，我们的方法显着优于Satlike3.0，最先进的本地搜索算法，用于解决PMS和WPMS问题。我们进一步与Satlike-C的扩展求解器进行比较，这是最近MaxSAT评估中不完全轨道的四个（PMS和WPMS类别相关的三类类别中的三个类别的冠军（MSE2021 ）。我们用拟议的远视采样本地搜索方法替换Satlike-C中的本地搜索组件，并且所产生的求解器FPS-C也优于Satlike-C来解决PMS和WPMS问题。

MD4 and MD5 are seminal cryptographic hash functions proposed in early 1990s. MD4 consists of 48 steps and produces a 128-bit hash given a message of arbitrary finite size. MD5 is a more secure 64-step extension of MD4. Both MD4 and MD5 are vulnerable to practical collision attacks, yet it is still not realistic to invert them, i.e. to find a message given a hash. In 2007, the 39-step version of MD4 was inverted via reducing to SAT and applying a CDCL solver along with the so-called Dobbertin's constraints. As for MD5, in 2012 its 28-step version was inverted via a CDCL solver for one specified hash without adding any additional constraints. In this study, Cube-and-Conquer (a combination of CDCL and lookahead) is applied to invert step-reduced versions of MD4 and MD5. For this purpose, two algorithms are proposed. The first one generates inversion problems for MD4 by gradually modifying the Dobbertin's constraints. The second algorithm tries the cubing phase of Cube-and-Conquer with different cutoff thresholds to find the one with minimal runtime estimation of the conquer phase. This algorithm operates in two modes: (i) estimating the hardness of an arbitrary given formula; (ii) incomplete SAT-solving of a given satisfiable formula. While the first algorithm is focused on inverting step-reduced MD4, the second one is not area-specific and so is applicable to a variety of classes of hard SAT instances. In this study, for the first time in history, 40-, 41-, 42-, and 43-step MD4 are inverted via the first algorithm and the estimating mode of the second algorithm. 28-step MD5 is inverted for four hashes via the incomplete SAT-solving mode of the second algorithm. For three hashes out of them this is done for the first time.

Partial MaxSAT (PMS) and Weighted PMS (WPMS) are two practical generalizations of the MaxSAT problem. In this paper, we propose a local search algorithm for these problems, called BandHS, which applies two multi-armed bandits to guide the search directions when escaping local optima. One bandit is combined with all the soft clauses to help the algorithm select to satisfy appropriate soft clauses, and the other bandit with all the literals in hard clauses to help the algorithm select appropriate literals to satisfy the hard clauses. These two bandits can improve the algorithm's search ability in both feasible and infeasible solution spaces. We further propose an initialization method for (W)PMS that prioritizes both unit and binary clauses when producing the initial solutions. Extensive experiments demonstrate the excellent performance and generalization capability of our proposed methods, that greatly boost the state-of-the-art local search algorithm, SATLike3.0, and the state-of-the-art SAT-based incomplete solver, NuWLS-c.

Generating diverse solutions to the Boolean Satisfiability Problem (SAT) is a hard computational problem with practical applications for testing and functional verification of software and hardware designs. We explore the way to generate such solutions using Denoising Diffusion coupled with a Graph Neural Network to implement the denoising function. We find that the obtained accuracy is similar to the currently best purely neural method and the produced SAT solutions are highly diverse, even if the system is trained with non-random solutions from a standard solver.

Cohn and Umans proposed a framework for developing fast matrix multiplication algorithms based on the embedding computation in certain groups algebras. In subsequent work with Kleinberg and Szegedy, they connected this to the search for combinatorial objects called strong uniquely solvable puzzles (strong USPs). We begin a systematic computer-aided search for these objects. We develop and implement constraint-based algorithms build on reductions to $\mathrm{SAT}$ and $\mathrm{IP}$ to verify that puzzles are strong USPs, and to search for large strong USPs. We produce tight bounds on the maximum size of a strong USP for width $k \le 5$, construct puzzles of small width that are larger than previous work, and improve the upper bounds on strong USP size for $k \le 12$. Although our work only deals with puzzles of small-constant width, the strong USPs we find imply matrix multiplication algorithms that run in $O(n^\omega)$ time with exponent $\omega \le 2.66$. While our algorithms do not beat the fastest algorithms, our work provides evidence and, perhaps, a path to finding families of strong USPs that imply matrix multiplication algorithms that are more efficient than those currently known.

工作流程满意度问题（WSP）是一个充分研究的问题，在访问控制方面寻求授权用户分配工作流程的每个步骤，但要受工作流规范约束。人们注意到，与WSP的现实世界实例中的用户数量相比，数字$ k $通常很少。因此，$ k $被认为是WSP参数复杂性研究中的参数。虽然通常证明WSP为W [1] -HARD，但WSP仅限于用户独立的（UI）约束的特殊情况，是固定参数可拖动的（FPT）。但是，对UI限制的限制可能是不切实际的。为了有效处理非UI约束，我们介绍了约束的分支因素的概念。只要约束的分支因子相对较小，并且非UI约束的数量是合理的，那么WSP就可以在fpt时间内解决。扩展了Karapetyan等人的结果。 （2019年），我们证明了通用求解器能够在与适当的配方一起使用时在WSP上实现与FPT一样的性能。这使人们能够解决大多数实用的WSP实例。尽管本身很重要，但我们希望这一结果还将激励研究人员寻找其他FPT问题的FPT感知表述。

命题满足（SAT）是一个NP完整的问题，它影响了许多研究领域，例如计划，验证和安全性。主流现代SAT求解器基于冲突驱动的子句学习（CDCL）算法。最近的工作旨在通过图神经网络（GNNS）产生的预测来改善其可变分支启发式方法来增强CDCL SAT求解器。但是，到目前为止，这种方法要么尚未使解决方案更有效，要么需要在线访问大量的GPU资源。为了使GNN改进实用，本文提出了一种称为Neurocomb的方法，该方法以两个见解为基础：（1）重要变量和条款的预测可以与动态分支相结合，为更有效的混合分支策略，（2）它是（2）它是足以在SAT解决开始之前仅查询神经模型一次。 NeuroComb被实施，以增强称为Minisat的经典CDCL求解器，以及最新的CDCL求解器，称为葡萄糖。结果，它允许Minisat在最近的SATCOMP-2021竞争问题设置中解决11％和葡萄糖更多的问题，仅计算资源需求只有一个GPU。因此，NeuroComb是通过机器学习改善SAT解决的有效和实用方法。

我们提出了一个通用图形神经网络体系结构，可以作为任何约束满意度问题（CSP）作为末端2端搜索启发式训练。我们的体系结构可以通过政策梯度下降进行无监督的培训，以纯粹的数据驱动方式为任何CSP生成问题的特定启发式方法。该方法基于CSP的新型图表，既是通用又紧凑的，并且使我们能够使用一个GNN处理所有可能的CSP实例，而不管有限的Arity，关系或域大小。与以前的基于RL的方法不同，我们在全局搜索动作空间上运行，并允许我们的GNN在随机搜索的每个步骤中修改任何数量的变量。这使我们的方法能够正确利用GNN的固有并行性。我们进行了彻底的经验评估，从随机数据（包括图形着色，Maxcut，3-SAT和Max-K-Sat）中学习启发式和重要的CSP。我们的方法表现优于先验的神经组合优化的方法。它可以在测试实例上与常规搜索启发式竞争，甚至可以改善几个数量级，结构上比训练中看到的数量级更为复杂。

Two contrasting algorithmic paradigms for constraint satisfaction problems are successive local explorations of neighboring configurations versus producing new configurations using global information about the problem (e.g. approximating the marginals of the probability distribution which is uniform over satisfying configurations). This paper presents new algorithms for the latter framework, ultimately producing estimates for satisfying configurations using methods from Boolean Fourier analysis. The approach is broadly inspired by the quantum amplitude amplification algorithm in that it maximally increases the amplitude of the approximation function over satisfying configurations given sequential refinements. We demonstrate that satisfying solutions may be retrieved in a process analogous to quantum measurement made efficient by sparsity in the Fourier domain, and present a complete solver construction using this novel approximation. Freedom in the refinement strategy invites further opportunities to design solvers in an evolutionary computing framework. Results demonstrate competitive performance against local solvers for the Boolean satisfiability (SAT) problem, encouraging future work in understanding the connections between Boolean Fourier analysis and constraint satisfaction.

我们解决了部分MaxSat（PMS）和加权PMS（WPM），这是MaxSat问题的两个实际概括，并为这些问题（称为BandMaxSat）提出了一种局部搜索算法，该算法应用了多臂Bantit模型来指导搜索方向。我们方法中的匪徒与输入（w）pms实例中的所有软子句相关联。每个手臂对应于软子句。 Bandit模型可以通过选择要在当前步骤中满足的软子句，即选择要拉的臂来帮助BandmaxSat选择一个良好的方向以逃脱本地Optima。我们进一步提出了一种初始化方法（w）PMS，在生产初始解决方案时优先考虑单元和二进制条款。广泛的实验表明，BandMaxSat显着优于最先进的（W）PMS本地搜索算法SATLIKE3.0。具体而言，BandMaxSat获得更好结果的实例数量大约是Satlike3.0获得的两倍。此外，我们将bandmaxsat与完整的求解器tt-open-wbo-inc相结合。最终的求解器bandmaxsat-c还胜过一些最好的最新完整（W）PMS求解器，包括satlike-c，loandra和tt-open-wbo-inc。

We present an approach for the verification of feed-forward neural networks in which all nodes have a piece-wise linear activation function. Such networks are often used in deep learning and have been shown to be hard to verify for modern satisfiability modulo theory (SMT) and integer linear programming (ILP) solvers.The starting point of our approach is the addition of a global linear approximation of the overall network behavior to the verification problem that helps with SMT-like reasoning over the network behavior. We present a specialized verification algorithm that employs this approximation in a search process in which it infers additional node phases for the non-linear nodes in the network from partial node phase assignments, similar to unit propagation in classical SAT solving. We also show how to infer additional conflict clauses and safe node fixtures from the results of the analysis steps performed during the search. The resulting approach is evaluated on collision avoidance and handwritten digit recognition case studies.

Multi-agent path finding (MAPF) is a task of finding non-conflicting paths connecting agents' specified initial and goal positions in a shared environment. We focus on compilation-based solvers in which the MAPF problem is expressed in a different well established formalism such as mixed-integer linear programming (MILP), Boolean satisfiability (SAT), or constraint programming (CP). As the target solvers for these formalisms act as black-boxes it is challenging to integrate MAPF specific heuristics in the MAPF compilation-based solvers. We show in this work how the build a MAPF encoding for the target SAT solver in which domain specific heuristic knowledge is reflected. The heuristic knowledge is transferred to the SAT solver by selecting candidate paths for each agent and by constructing the encoding only for these candidate paths instead of constructing the encoding for all possible paths for an agent. The conducted experiments show that heuristically guided compilation outperforms the vanilla variants of the SAT-based MAPF solver.

随着深度学习技术的快速发展，各种最近的工作试图应用图形神经网络（GNN）来解决诸如布尔满足（SAT）之类的NP硬问题，这表明了桥接机器学习与象征性差距的潜力。然而，GNN预测的解决方案的质量并未在文献中进行很好地研究。在本文中，我们研究了GNNS在学习中解决最大可满足性（MaxSAT）问题的能力，从理论和实践角度来看。我们构建了两种GNN模型来学习来自基准的MaxSAT实例的解决方案，并显示GNN通过实验评估解决MaxSAT问题的有吸引力。我们还基于算法对准理论，我们还提出了GNNS可以在一定程度上学会解决MaxSAT问题的影响的理论解释。