计量经济学和机器学习中的各种问题,包括仪器变量回归和钟声残留最小化,可以表达为满足一组条件矩限制(CMR)。我们得出了满足CMR的一般游戏理论策略,该策略可扩展到非线性问题,可与基于梯度的优化相提并论,并且能够考虑有限的样本不确定性。我们恢复了Dikkala等人的方法。和Dai等。作为我们一般框架的特殊情况,请先详细介绍各种扩展,以及如何有效地解决CMR定义的游戏。
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我们考虑模仿学习问题,在这些问题中,专家可以在演示时间和测试时间内访问学习者隐藏的每个集合上下文。尽管学习者可能无法通过考虑整个国家和行动的历史来早期在情节中准确地重现专家行为,但他们可能最终能够识别上下文并像专家一样行事。我们证明,与非政策的方法相比,在政策模仿学习算法(有或不访问可查询的专家)都可以更好地处理这些渐近性问题,并且能够避免闩锁行为(对过去的动作的天真重复)这困扰着后者。我们在玩具匪徒域中进行实验,该实验表明,与统一的policy方法的均匀性能相比,非政策方法是否能够渐近地匹配专家的性能。我们证明,在几个连续的控制任务上,政策方法能够使用历史记录来识别上下文,而在访问历史记录时,违反政策方法实际上表现较差。
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在线模仿学习是如何最好地访问环境或准确的模拟器的问题的问题。先前的工作表明,在无限的样本制度中,匹配的确切力矩达到了与专家政策的价值等效性。但是,在有限的样本制度中,即使没有优化错误,经验差异也会导致性能差距,该差距以$ h^2 / n $的行为克隆缩放,在线时刻$ h / \ sqrt {n} $匹配,其中$ h $是地平线,$ n $是专家数据集的大小。我们介绍了重播估算的技术以减少这种经验差异:通过反复在随机模拟器中执行缓存的专家动作,我们计算了一个更平滑的专家访问分布估算以匹配的。在存在一般函数近似的情况下,我们证明了一个元定理,可以减少离线分类参数估计误差的方法差距(即学习专家策略)。在表格设置或使用线性函数近似中,我们的元定理表明,我们方法产生的性能差距达到了最佳$ \ widetilde {o} \ left(\ min(\ min({h^h^{3/2}}}} / {n} ,{h} / {\ sqrt {n}} \ right)$依赖关系,在与先前的工作相比明显弱的假设下。我们在多个连续的控制任务上实施了多个方法的多次实例化,并发现我们能够显着提高策略绩效跨各种数据集尺寸。
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Artificial Intelligence (AI) has become commonplace to solve routine everyday tasks. Because of the exponential growth in medical imaging data volume and complexity, the workload on radiologists is steadily increasing. We project that the gap between the number of imaging exams and the number of expert radiologist readers required to cover this increase will continue to expand, consequently introducing a demand for AI-based tools that improve the efficiency with which radiologists can comfortably interpret these exams. AI has been shown to improve efficiency in medical-image generation, processing, and interpretation, and a variety of such AI models have been developed across research labs worldwide. However, very few of these, if any, find their way into routine clinical use, a discrepancy that reflects the divide between AI research and successful AI translation. To address the barrier to clinical deployment, we have formed MONAI Consortium, an open-source community which is building standards for AI deployment in healthcare institutions, and developing tools and infrastructure to facilitate their implementation. This report represents several years of weekly discussions and hands-on problem solving experience by groups of industry experts and clinicians in the MONAI Consortium. We identify barriers between AI-model development in research labs and subsequent clinical deployment and propose solutions. Our report provides guidance on processes which take an imaging AI model from development to clinical implementation in a healthcare institution. We discuss various AI integration points in a clinical Radiology workflow. We also present a taxonomy of Radiology AI use-cases. Through this report, we intend to educate the stakeholders in healthcare and AI (AI researchers, radiologists, imaging informaticists, and regulators) about cross-disciplinary challenges and possible solutions.
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The demonstrated success of transfer learning has popularized approaches that involve pretraining models from massive data sources and subsequent finetuning towards a specific task. While such approaches have become the norm in fields such as natural language processing, implementation and evaluation of transfer learning approaches for chemistry are in the early stages. In this work, we demonstrate finetuning for downstream tasks on a graph neural network (GNN) trained over a molecular database containing 2.7 million water clusters. The use of Graphcore IPUs as an AI accelerator for training molecular GNNs reduces training time from a reported 2.7 days on 0.5M clusters to 1.2 hours on 2.7M clusters. Finetuning the pretrained model for downstream tasks of molecular dynamics and transfer to a different potential energy surface took only 8.3 hours and 28 minutes, respectively, on a single GPU.
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By utilizing only depth information, the paper introduces a novel but efficient local planning approach that enhances not only computational efficiency but also planning performances for memoryless local planners. The sampling is first proposed to be based on the depth data which can identify and eliminate a specific type of in-collision trajectories in the sampled motion primitive library. More specifically, all the obscured primitives' endpoints are found through querying the depth values and excluded from the sampled set, which can significantly reduce the computational workload required in collision checking. On the other hand, we furthermore propose a steering mechanism also based on the depth information to effectively prevent an autonomous vehicle from getting stuck when facing a large convex obstacle, providing a higher level of autonomy for a planning system. Our steering technique is theoretically proved to be complete in scenarios of convex obstacles. To evaluate effectiveness of the proposed DEpth based both Sampling and Steering (DESS) methods, we implemented them in the synthetic environments where a quadrotor was simulated flying through a cluttered region with multiple size-different obstacles. The obtained results demonstrate that the proposed approach can considerably decrease computing time in local planners, where more trajectories can be evaluated while the best path with much lower cost can be found. More importantly, the success rates calculated by the fact that the robot successfully navigated to the destinations in different testing scenarios are always higher than 99.6% on average.
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Leveraging shared learning through Massively Multilingual Models, state-of-the-art machine translation models are often able to adapt to the paucity of data for low-resource languages. However, this performance comes at the cost of significantly bloated models which are not practically deployable. Knowledge Distillation is one popular technique to develop competitive, lightweight models: In this work, we first evaluate its use to compress MT models focusing on languages with extremely limited training data. Through our analysis across 8 languages, we find that the variance in the performance of the distilled models due to their dependence on priors including the amount of synthetic data used for distillation, the student architecture, training hyperparameters and confidence of the teacher models, makes distillation a brittle compression mechanism. To mitigate this, we explore the use of post-training quantization for the compression of these models. Here, we find that while distillation provides gains across some low-resource languages, quantization provides more consistent performance trends for the entire range of languages, especially the lowest-resource languages in our target set.
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目前,自然语言理解(NLU)中最根本的两个挑战是:(a)如何以“正确”的原因确定基于深度学习的模型是否在NLU基准上得分很高;(b)了解这些原因甚至是什么。我们研究了关于两个语言“技能”的阅读理解模型的行为:核心分辨率和比较。我们为从系统中预期的推理步骤提出了一个定义,该系统将“缓慢阅读”,并将其与各种大小的贝特家族的五个模型的行为进行比较,这是通过显着分数和反事实解释观察到的。我们发现,对于比较(而不是核心),基于较大编码器的系统更有可能依靠“正确”的信息,但即使他们在概括方面也很难,表明他们仍然学习特定的词汇模式,而不是比较的一般原则。
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为了简化图书馆管理的过程,已经采用了许多技术,但其中大多数专注于库存管理。在发行和返回图书馆的发行和返回图书馆的领域,几乎没有任何自动化进展。在大学和学校中,宿舍经常忘记及时将发行的书籍返回图书馆。为了解决上述问题并确保及时提交已发行的书籍,这项工作开发了一个解决这些复杂性的书籍机器人。该机器人可以从A点到B点通勤,扫描并验证QR码和条形码。该机器人将具有一定的有效载荷能力来携带书籍。 QR码和条形码扫描将由PI摄像头,OpenCV和Raspberry Pi启用,从而使书籍交换安全。机器人的探测器操作将通过Blynk应用程序手动控制。本文着重于如何减少人类干预,并在机器人的帮助下自动化图书馆管理系统的问题。
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自然语言推理(NLI)任务通常需要通过多个步骤进行推理才能得出结论。尽管产生此类中间步骤的必要性(而不是摘要说明)获得了大众支持,但尚不清楚如何在不完全端到端的监督以及如何进一步利用此类步骤的情况下生成此类步骤。在这项工作中,我们训练一个序列到序列模型,仅生成下一步给定NLI前提和假设对(以及先前的步骤);然后通过外部知识和符号搜索来增强它,以仅在下一步监督下生成中间步骤。我们通过自动化和人类验证显示了此类生成的步骤的正确性。此外,我们表明,这种生成的步骤可以通过多个公共NLI数据集使用简单的数据增强策略来帮助提高端到端的NLI任务性能。
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