在基于学术和行业的研究中,在线评估方法都被视为推荐系统等交互式应用程序的黄金标准。自然,这样做的原因是,我们可以直接测量依赖干预措施的实用程序指标,这是向用户显示的建议。然而,由于多种原因,在线评估方法是昂贵的,并且对于可靠的离线评估程序仍然存在明确的需求。在行业中,离线指标通常被用作一线评估,以生成有前途的候选模型来在线评估。在学术工作中,对在线系统的有限访问使离线指标是验证新方法的事实上的方法。存在两个类别的离线指标:基于代理的方法和反事实方法。头等舱通常与我们关心的在线指标相关,而后一类仅根据在现实世界中无法实现的假设提供理论保证。在这里,我们表明基于模拟的比较为离线指标提供了前进的方向,并认为它们是可取的评估手段。
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我们介绍了概率等级和奖励模型(PRR),这是一个可扩展的概率模型,用于个性化的Slate建议。我们的模型允许在以下无处不在的推荐系统方案中对用户兴趣的最新估计:向用户显示了k个建议的板岩,用户最多可以选择这些K项目中的一个。推荐系统的目标是找到用户最感兴趣的K项目,以最大程度地提高用户与Slate交互的可能性。我们的贡献是表明,我们可以通过结合奖励(无论是否单击板岩,以及等级)而更有效地学习建议成功的可能性。我们的方法比仅使用奖励和仅使用等级的用户偏好方法的盗销方法更有效地学习。它还提供了与独立的逆点分数方法相似或更好的估计性能,并且更可扩展。我们的方法是在大量数据集中的速度和准确性方面的最高速度,最多100万个项目。最后,我们的方法允许快速交付由最大内部产品搜索(MIPS)提供动力的建议,使其适用于极低的延迟域,例如计算广告。
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个性化交互式系统(例如推荐系统)需要选择取决于上下文的相关项目。生产系统需要从非常大的目录中迅速识别这些项目,这些目录可以使用最大的内部产品搜索技术有效地解决。通过放松离散问题,可以实现最大内部产品搜索的离线优化,从而导致政策学习或增强样式学习算法。不幸的是,这种放松步骤需要在整个目录上计算一个总和,从而使梯度评估的复杂性(因此每个随机梯度下降迭代)在目录大小中线性线性。在许多现实世界中,该计算是站不住脚的示例,例如大型目录推荐系统严重限制了该方法在实践中的实用性。在本文中,我们展示了如何产生这些政策学习算法的出色近似值,以对数与目录大小进行对数。我们的贡献是基于结合三个新颖想法的结合:对政策梯度,自我正常化的重要性采样估计器以及在训练时使用快速最大内部产品搜索的新蒙特卡洛估计。广泛的实验表明,我们的算法比幼稚的方法更快,但产生同样好的策略。
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因果关系的概念具有争议的历史。是否有可能代表和解决具有概率理论的因果问题的问题,或者如果需要大大新的数学,则需要进行热争论,例如,需要进行DO微积分。珍珠(2001年)国家“我们科学和日常知识的建筑块是”泥浆并没有引起雨“,”症状不会引起疾病“以及这些事实,奇怪的是,不能在概率的词汇表中表达结石”。这导致因果图形建模和DO微积分的主张与应用贝叶斯方法的研究人员之间的二分法。在本文中,我们证明,如果我们这样做,虽然明确地模拟了干预系统中的影响的假设,但是可以完全在标准贝叶斯范式内完成估算因果效应。底层原因图形模型的不变假设可以在普通概率图形模型中编码,允许与贝叶斯统计数据的因果估计,相当于DO微积分。阐明这些方法之间的连接是使每个接近能够组合以解决实际问题的关键步骤。
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In this paper, we propose a novel technique, namely INVALIDATOR, to automatically assess the correctness of APR-generated patches via semantic and syntactic reasoning. INVALIDATOR reasons about program semantic via program invariants while it also captures program syntax via language semantic learned from large code corpus using the pre-trained language model. Given a buggy program and the developer-patched program, INVALIDATOR infers likely invariants on both programs. Then, INVALIDATOR determines that a APR-generated patch overfits if: (1) it violates correct specifications or (2) maintains errors behaviors of the original buggy program. In case our approach fails to determine an overfitting patch based on invariants, INVALIDATOR utilizes a trained model from labeled patches to assess patch correctness based on program syntax. The benefit of INVALIDATOR is three-fold. First, INVALIDATOR is able to leverage both semantic and syntactic reasoning to enhance its discriminant capability. Second, INVALIDATOR does not require new test cases to be generated but instead only relies on the current test suite and uses invariant inference to generalize the behaviors of a program. Third, INVALIDATOR is fully automated. We have conducted our experiments on a dataset of 885 patches generated on real-world programs in Defects4J. Experiment results show that INVALIDATOR correctly classified 79% overfitting patches, accounting for 23% more overfitting patches being detected by the best baseline. INVALIDATOR also substantially outperforms the best baselines by 14% and 19% in terms of Accuracy and F-Measure, respectively.
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The recent increase in public and academic interest in preserving biodiversity has led to the growth of the field of conservation technology. This field involves designing and constructing tools that utilize technology to aid in the conservation of wildlife. In this article, we will use case studies to demonstrate the importance of designing conservation tools with human-wildlife interaction in mind and provide a framework for creating successful tools. These case studies include a range of complexities, from simple cat collars to machine learning and game theory methodologies. Our goal is to introduce and inform current and future researchers in the field of conservation technology and provide references for educating the next generation of conservation technologists. Conservation technology not only has the potential to benefit biodiversity but also has broader impacts on fields such as sustainability and environmental protection. By using innovative technologies to address conservation challenges, we can find more effective and efficient solutions to protect and preserve our planet's resources.
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Variational autoencoders model high-dimensional data by positing low-dimensional latent variables that are mapped through a flexible distribution parametrized by a neural network. Unfortunately, variational autoencoders often suffer from posterior collapse: the posterior of the latent variables is equal to its prior, rendering the variational autoencoder useless as a means to produce meaningful representations. Existing approaches to posterior collapse often attribute it to the use of neural networks or optimization issues due to variational approximation. In this paper, we consider posterior collapse as a problem of latent variable non-identifiability. We prove that the posterior collapses if and only if the latent variables are non-identifiable in the generative model. This fact implies that posterior collapse is not a phenomenon specific to the use of flexible distributions or approximate inference. Rather, it can occur in classical probabilistic models even with exact inference, which we also demonstrate. Based on these results, we propose a class of latent-identifiable variational autoencoders, deep generative models which enforce identifiability without sacrificing flexibility. This model class resolves the problem of latent variable non-identifiability by leveraging bijective Brenier maps and parameterizing them with input convex neural networks, without special variational inference objectives or optimization tricks. Across synthetic and real datasets, latent-identifiable variational autoencoders outperform existing methods in mitigating posterior collapse and providing meaningful representations of the data.
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Cashews are grown by over 3 million smallholders in more than 40 countries worldwide as a principal source of income. As the third largest cashew producer in Africa, Benin has nearly 200,000 smallholder cashew growers contributing 15% of the country's national export earnings. However, a lack of information on where and how cashew trees grow across the country hinders decision-making that could support increased cashew production and poverty alleviation. By leveraging 2.4-m Planet Basemaps and 0.5-m aerial imagery, newly developed deep learning algorithms, and large-scale ground truth datasets, we successfully produced the first national map of cashew in Benin and characterized the expansion of cashew plantations between 2015 and 2021. In particular, we developed a SpatioTemporal Classification with Attention (STCA) model to map the distribution of cashew plantations, which can fully capture texture information from discriminative time steps during a growing season. We further developed a Clustering Augmented Self-supervised Temporal Classification (CASTC) model to distinguish high-density versus low-density cashew plantations by automatic feature extraction and optimized clustering. Results show that the STCA model has an overall accuracy of 80% and the CASTC model achieved an overall accuracy of 77.9%. We found that the cashew area in Benin has doubled from 2015 to 2021 with 60% of new plantation development coming from cropland or fallow land, while encroachment of cashew plantations into protected areas has increased by 70%. Only half of cashew plantations were high-density in 2021, suggesting high potential for intensification. Our study illustrates the power of combining high-resolution remote sensing imagery and state-of-the-art deep learning algorithms to better understand tree crops in the heterogeneous smallholder landscape.
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Coronary Computed Tomography Angiography (CCTA) provides information on the presence, extent, and severity of obstructive coronary artery disease. Large-scale clinical studies analyzing CCTA-derived metrics typically require ground-truth validation in the form of high-fidelity 3D intravascular imaging. However, manual rigid alignment of intravascular images to corresponding CCTA images is both time consuming and user-dependent. Moreover, intravascular modalities suffer from several non-rigid motion-induced distortions arising from distortions in the imaging catheter path. To address these issues, we here present a semi-automatic segmentation-based framework for both rigid and non-rigid matching of intravascular images to CCTA images. We formulate the problem in terms of finding the optimal \emph{virtual catheter path} that samples the CCTA data to recapitulate the coronary artery morphology found in the intravascular image. We validate our co-registration framework on a cohort of $n=40$ patients using bifurcation landmarks as ground truth for longitudinal and rotational registration. Our results indicate that our non-rigid registration significantly outperforms other co-registration approaches for luminal bifurcation alignment in both longitudinal (mean mismatch: 3.3 frames) and rotational directions (mean mismatch: 28.6 degrees). By providing a differentiable framework for automatic multi-modal intravascular data fusion, our developed co-registration modules significantly reduces the manual effort required to conduct large-scale multi-modal clinical studies while also providing a solid foundation for the development of machine learning-based co-registration approaches.
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Springs are efficient in storing and returning elastic potential energy but are unable to hold the energy they store in the absence of an external load. Lockable springs use clutches to hold elastic potential energy in the absence of an external load but have not yet been widely adopted in applications, partly because clutches introduce design complexity, reduce energy efficiency, and typically do not afford high-fidelity control over the energy stored by the spring. Here, we present the design of a novel lockable compression spring that uses a small capstan clutch to passively lock a mechanical spring. The capstan clutch can lock up to 1000 N force at any arbitrary deflection, unlock the spring in less than 10 ms with a control force less than 1 % of the maximal spring force, and provide an 80 % energy storage and return efficiency (comparable to a highly efficient electric motor operated at constant nominal speed). By retaining the form factor of a regular spring while providing high-fidelity locking capability even under large spring forces, the proposed design could facilitate the development of energy-efficient spring-based actuators and robots.
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