We propose a trust-region stochastic sequential quadratic programming algorithm (TR-StoSQP) to solve nonlinear optimization problems with stochastic objectives and deterministic equality constraints. We consider a fully stochastic setting, where in each iteration a single sample is generated to estimate the objective gradient. The algorithm adaptively selects the trust-region radius and, compared to the existing line-search StoSQP schemes, allows us to employ indefinite Hessian matrices (i.e., Hessians without modification) in SQP subproblems. As a trust-region method for constrained optimization, our algorithm needs to address an infeasibility issue -- the linearized equality constraints and trust-region constraints might lead to infeasible SQP subproblems. In this regard, we propose an \textit{adaptive relaxation technique} to compute the trial step that consists of a normal step and a tangential step. To control the lengths of the two steps, we adaptively decompose the trust-region radius into two segments based on the proportions of the feasibility and optimality residuals to the full KKT residual. The normal step has a closed form, while the tangential step is solved from a trust-region subproblem, to which a solution ensuring the Cauchy reduction is sufficient for our study. We establish the global almost sure convergence guarantee for TR-StoSQP, and illustrate its empirical performance on both a subset of problems in the CUTEst test set and constrained logistic regression problems using data from the LIBSVM collection.
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组合推荐人(CR)系统一次在结果页面中一次将项目列表馈送给用户,其中用户行为受到上下文信息和项目的影响。 CR被称为组合优化问题,目的是最大程度地提高整个列表的建议奖励。尽管它很重要,但由于在线环境中的效率,动态和个性化要求,建立实用的CR系统仍然是一个挑战。特别是,我们将问题分为两个子问题,即列表生成和列表评估。新颖和实用的模型体系结构是为这些子问题设计的,旨在共同优化有效性和效率。为了适应在线案例,给出了形成参与者批判性增强框架的自举算法,以探索在长期用户互动中更好的推荐模式。离线和在线实验结果证明了拟议的JDREC框架的功效。 JDREC已应用于在线JD建议中,将点击率提高了2.6%,平台的合成价值提高了5.03%。我们将发布本研究中使用的大规模数据集,以为研究界做出贡献。
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(源)代码摘要旨在以自然语言的形式自动为给定代码段生成摘要/注释。此类摘要在帮助开发人员理解和维护源代码方面起着关键作用。现有的代码摘要技术可以分类为提取方法和抽象方法。提取方法使用检索技术从代码段中提取重要语句和关键字的子集,并生成一个摘要,该摘要保留了重要语句和关键字中的事实详细信息。但是,这样的子集可能会错过标识符或实体命名,因此,产生的摘要的自然性通常很差。抽象方法可以生成类似人写的摘要,从而利用神经机器翻译域的编码器模型。然而,生成的摘要通常会错过重要的事实细节。为了通过保留的事实细节生成类似人写的摘要,我们提出了一个新颖的提取和吸收框架。框架中的提取模块执行了提取代码摘要的任务,该任务列入了代码段,并预测包含关键事实细节的重要陈述。框架中的抽象模块执行了抽象代码摘要的任务,该任务是在整个代码段和并行的重要陈述中进行的,并生成了简洁而人工写的类似的自然语言摘要。我们通过在涉及六种编程语言的三个数据集上进行广泛的实验来评估称为EACS的有效性。实验结果表明,在所有三种广泛使用的指标(包括BLEU,流星和Rough-l)方面,EACS明显优于最先进的技术。
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交通预测在智能运输系统中起着不可或缺的作用,使每日旅行更方便和更安全。然而,时空相关的动态演化使得准确的流量预测非常困难。现有工作主要采用图形神经NetWroks(GNNS)和深度时间序列模型(例如,复发性神经网络),以捕获动态交通系统中的复杂时空模式。对于空间模式,GNN难以在道路网络中提取全局空间信息,即远程传感器信息。虽然我们可以使用自我关注来提取全球空间信息,如前面的工作中,它也伴随着巨大的资源消耗。对于时间模式,交通数据不仅易于识别每日和每周趋势,而且难以识别由事故引起的短期噪音(例如,汽车事故和雷暴)。现有交通模型难以在时间序列中区分复杂的时间模式,因此难以实现准确的时间依赖。为了解决上述问题,我们提出了一种新颖的噪声感知高效时空变压器架构,用于准确的交通预测,名为StFormer。 Stformer由两个组件组成,这是噪声感知的时间自我关注(NATSA)和基于图形的稀疏空间自我关注(GBS3A)。 NATSA将高频分量和低频分量与时间序列分开以消除噪声并分别通过学习滤波器和时间自我关注捕获稳定的时间依赖性。 GBS3A以基于图形的稀疏查询替换vanilla自我关注的完整查询,以减少时间和内存使用情况。四个现实世界交通数据集的实验表明,履带器优于较低的计算成本的最先进的基线。
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交通预测在智能交通系统中很重要,有利于交通安全,但由于现实世界交通系统中的复杂和动态的时空依赖性,这是非常具有挑战性的。先前的方法使用预定义或学习的静态图来提取空间相关性。但是,基于静态图形的方法无法挖掘交通网络的演变。研究人员随后为每次切片生成动态图形以反映空间相关性的变化,但它们遵循独立建模的时空依赖性的范例,忽略了串行空间影响。在本文中,我们提出了一种新的基于跨时动态图形的深度学习模型,名为CDGNet,用于交通预测。该模型能够通过利用横行动态图来有效地捕获每个时切片和其历史时片之间的串联空间依赖性。同时,我们设计了稀疏横行动态图的浇注机制,符合现实世界中的稀疏空间相关性。此外,我们提出了一种新颖的编码器解码器架构,用于结合基于交叉时间动态图形的GCN,用于多步行量预测。三个现实世界公共交通数据集的实验结果表明CDGNET优于最先进的基线。我们还提供了一种定性研究来分析我们建筑的有效性。
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交通预测是智能交通系统的问题(ITS),并为个人和公共机构是至关重要的。因此,研究高度重视应对准确预报交通系统的复杂的时空相关性。但是,有两个挑战:1)大多数流量预测研究主要集中在造型相邻传感器的相关性,而忽略远程传感器,例如,商务区有类似的时空模式的相关性; 2)使用静态邻接矩阵中曲线图的卷积网络(GCNs)的现有方法不足以反映在交通系统中的动态空间依赖性。此外,它采用自注意所有的传感器模型动态关联细粒度方法忽略道路网络分层信息,并有二次计算复杂性。在本文中,我们提出了一种新动态多图形卷积递归网络(DMGCRN),以解决上述问题,可以同时距离的空间相关性,结构的空间相关性,和所述时间相关性进行建模。那么,只使用基于距离的曲线图来捕获空间信息从节点是接近距离也构建了一个新潜曲线图,其编码的道路之间的相关性的结构来捕获空间信息从节点在结构上相似。此外,我们在不同的时间将每个传感器的邻居到粗粒区域,并且动态地分配不同的权重的每个区域。同时,我们整合动态多图卷积网络到门控重复单元(GRU)来捕获时间依赖性。三个真实世界的交通数据集大量的实验证明,我们提出的算法优于国家的最先进的基线。
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由于流量大数据的增加,交通预测逐渐引起了研究人员的注意力。因此,如何在交通数据中挖掘复杂的时空相关性以预测交通状况更准确地成为难题。以前的作品组合图形卷积网络(GCNS)和具有深度序列模型的自我关注机制(例如,复发性神经网络),分别捕获时空相关性,忽略时间和空间的关系。此外,GCNS受到过平滑问题的限制,自我关注受到二次问题的限制,导致GCN缺乏全局代表能力,自我注意力效率低下捕获全球空间依赖性。在本文中,我们提出了一种新颖的交通预测深入学习模型,命名为多语境意识的时空关节线性关注(STJLA),其对时空关节图应用线性关注以捕获所有时空之间的全球依赖性节点有效。更具体地,STJLA利用静态结构上下文和动态语义上下文来提高模型性能。基于Node2VEC和单热编码的静态结构上下文丰富了时空位置信息。此外,基于多头扩散卷积网络的动态空间上下文增强了局部空间感知能力,并且基于GRU的动态时间上下文分别稳定了线性关注的序列位置信息。在两个现实世界交通数据集,英格兰和PEMSD7上的实验表明,我们的Stjla可以获得高达9.83%和3.08%,在最先进的基线上的衡量标准的准确性提高。
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Benefiting from the intrinsic supervision information exploitation capability, contrastive learning has achieved promising performance in the field of deep graph clustering recently. However, we observe that two drawbacks of the positive and negative sample construction mechanisms limit the performance of existing algorithms from further improvement. 1) The quality of positive samples heavily depends on the carefully designed data augmentations, while inappropriate data augmentations would easily lead to the semantic drift and indiscriminative positive samples. 2) The constructed negative samples are not reliable for ignoring important clustering information. To solve these problems, we propose a Cluster-guided Contrastive deep Graph Clustering network (CCGC) by mining the intrinsic supervision information in the high-confidence clustering results. Specifically, instead of conducting complex node or edge perturbation, we construct two views of the graph by designing special Siamese encoders whose weights are not shared between the sibling sub-networks. Then, guided by the high-confidence clustering information, we carefully select and construct the positive samples from the same high-confidence cluster in two views. Moreover, to construct semantic meaningful negative sample pairs, we regard the centers of different high-confidence clusters as negative samples, thus improving the discriminative capability and reliability of the constructed sample pairs. Lastly, we design an objective function to pull close the samples from the same cluster while pushing away those from other clusters by maximizing and minimizing the cross-view cosine similarity between positive and negative samples. Extensive experimental results on six datasets demonstrate the effectiveness of CCGC compared with the existing state-of-the-art algorithms.
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As one of the prevalent methods to achieve automation systems, Imitation Learning (IL) presents a promising performance in a wide range of domains. However, despite the considerable improvement in policy performance, the corresponding research on the explainability of IL models is still limited. Inspired by the recent approaches in explainable artificial intelligence methods, we proposed a model-agnostic explaining framework for IL models called R2RISE. R2RISE aims to explain the overall policy performance with respect to the frames in demonstrations. It iteratively retrains the black-box IL model from the randomized masked demonstrations and uses the conventional evaluation outcome environment returns as the coefficient to build an importance map. We also conducted experiments to investigate three major questions concerning frames' importance equality, the effectiveness of the importance map, and connections between importance maps from different IL models. The result shows that R2RISE successfully distinguishes important frames from the demonstrations.
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Increasing research interests focus on sequential recommender systems, aiming to model dynamic sequence representation precisely. However, the most commonly used loss function in state-of-the-art sequential recommendation models has essential limitations. To name a few, Bayesian Personalized Ranking (BPR) loss suffers the vanishing gradient problem from numerous negative sampling and predictionbiases; Binary Cross-Entropy (BCE) loss subjects to negative sampling numbers, thereby it is likely to ignore valuable negative examples and reduce the training efficiency; Cross-Entropy (CE) loss only focuses on the last timestamp of the training sequence, which causes low utilization of sequence information and results in inferior user sequence representation. To avoid these limitations, in this paper, we propose to calculate Cumulative Cross-Entropy (CCE) loss over the sequence. CCE is simple and direct, which enjoys the virtues of painless deployment, no negative sampling, and effective and efficient training. We conduct extensive experiments on five benchmark datasets to demonstrate the effectiveness and efficiency of CCE. The results show that employing CCE loss on three state-of-the-art models GRU4Rec, SASRec, and S3-Rec can reach 125.63%, 69.90%, and 33.24% average improvement of full ranking NDCG@5, respectively. Using CCE, the performance curve of the models on the test data increases rapidly with the wall clock time, and is superior to that of other loss functions in almost the whole process of model training.
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