Attention-based multiple instance learning (AMIL) algorithms have proven to be successful in utilizing gigapixel whole-slide images (WSIs) for a variety of different computational pathology tasks such as outcome prediction and cancer subtyping problems. We extended an AMIL approach to the task of survival prediction by utilizing the classical Cox partial likelihood as a loss function, converting the AMIL model into a nonlinear proportional hazards model. We applied the model to tissue microarray (TMA) slides of 330 lung cancer patients. The results show that AMIL approaches can handle very small amounts of tissue from a TMA and reach similar C-index performance compared to established survival prediction methods trained with highly discriminative clinical factors such as age, cancer grade, and cancer stage
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自从人类文明的早期阶段以来已知的石榴石在现代技术中发现了重要的应用,包括磁性限制,Spintronics,锂电池等。绝大多数实验性的石榴石是氧化物,而探索(实验或理论)在其余的探索中是氧化物化学空间的范围受到限制。一个关键问题是石榴石结构具有较大的原始单位单元格,需要大量的计算资源。为了对新石榴石的完整化学空间进行全面搜索,我们将图形神经网络中的最新进展与高通量计算结合在一起。我们应用机器学习模型来在系统密度功能的计算之前识别电势(meta-)稳定的石榴石系统以验证预测。通过这种方式,我们发现了600多个三元石榴石,距凸壳以下的凸壳距离低于100〜MEV/ATOM,具有各种物理和化学性质。这包括硫化物,氮化物和卤化物石榴石。为此,我们分析电子结构,并讨论电子带隙和电荷平衡的值之间的联系。
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我们考虑在线模仿学习(OIL),其中的任务是找到一项通过与环境的积极互动来模仿专家的行为的政策。我们旨在通过分析最流行的石油算法之一匕首来弥合石油政策优化算法之间的差距。具体而言,如果一类政策足以包含专家政策,我们证明匕首会持续遗憾。与以前需要损失的界限不同,我们的结果只需要较弱的假设,即损失相对于策略的足够统计数据(而不是其参数化)。为了确保对更广泛的政策和损失类别的收敛,我们以额外的正则化项增强了匕首。特别是,我们提出了一个遵循定制领导者(FTRL)的变体及其用于石油的自适应变体,并开发了与FTL的内存需求相匹配的记忆效率实现。假设损失的功能是平稳的,并且相对于政策参数凸出,我们还证明,FTRL对任何足够表达的政策类别都持续遗憾,同时保留了$ O(\ sqrt {t})$,在最坏的情况下遗憾案子。我们通过实验对合成和高维控制任务的实验证明了这些算法的有效性。
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通过一系列联邦举措和命令,美国政府一直在努力确保美国在AI中的领导。这些广泛的战略文件影响了美国空军美国部(DAF)等组织。DAF-MIT AI加速器是DAF和MIT之间的一项计划,以弥合AI研究人员与DAF任务要求之间的差距。DAF-MIT AI加速器支持的几个项目正在开发公共挑战问题,这些问题解决了许多联邦AI研究的重点。这些挑战是通过公开可用的大型AI-Ready数据集,激励开源解决方案,并为可以激发进一步研究的双重使用技术创建需求信号,来针对优先事项。在本文中,我们描述了正在开发的这些公共挑战以及它们的应用如何促进科学进步。
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语言模型既展示了定量的改进,又展示了新的定性功能,随着规模的增加。尽管它们具有潜在的变革性影响,但这些新能力的特征却很差。为了为未来的研究提供信息,为破坏性的新模型能力做准备,并改善社会有害的效果,至关重要的是,我们必须了解目前和近乎未来的能力和语言模型的局限性。为了应对这一挑战,我们介绍了超越模仿游戏基准(Big Bench)。 Big Bench目前由204个任务组成,由132家机构的442位作者贡献。任务主题是多样的,从语言学,儿童发展,数学,常识性推理,生物学,物理学,社会偏见,软件开发等等。 Big-Bench专注于被认为超出当前语言模型的功能的任务。我们评估了OpenAI的GPT型号,Google内部密集变压器体系结构和大型基础上的开关稀疏变压器的行为,跨越了数百万到数十亿个参数。此外,一个人类专家评估者团队执行了所有任务,以提供强大的基准。研究结果包括:模型性能和校准都随规模改善,但绝对的术语(以及与评估者的性能相比);在模型类中的性能非常相似,尽管带有稀疏性。逐渐和预测的任务通常涉及大量知识或记忆成分,而在临界规模上表现出“突破性”行为的任务通常涉及多个步骤或组成部分或脆性指标;社交偏见通常会随着含糊不清的环境而随着规模而增加,但这可以通过提示来改善。
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概率数值方法(PNMS)通过概率推断解决数值问题。它们已开发用于线性代数,优化,集成和微分方程模拟。PNMS自然地纳入了关于问题的先前信息,并通过有限计算资源以及随机输入来量化不确定性。在本文中,我们提出了probnum:提供最先进的概率数值求解器的Python库。Probnum通过模块化设计以及包装器,可以通过模块化设计来定制PNMS的定制组成,以供自卸使用。在线,在线,文档,开发人员指南和基准,请访问www.probnum.org。
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具有微分方程的机械模型是机器学习科学应用的关键组成部分。这种模型中的推论通常在计算上是要求的,因为它涉及重复求解微分方程。这里的主要问题是数值求解器很难与标准推理技术结合使用。概率数字中的最新工作已经开发了一类新的用于普通微分方程(ODE)的求解器,该方程式直接用贝叶斯过滤词来表达解决方案过程。我们在这里表明,这允许将此类方法与概念和数值易于宽容地结合在一起,并在ODE本身中与潜在力模型结合在一起。然后,可以在潜在力和ode溶液上执行近似贝叶斯推断,并在一个线性复杂度传递中进行扩展的卡尔曼滤波器 /更平滑的线性复杂度,也就是说,以计算单个ODE解决方案为代价。我们通过培训表明了算法的表达和性能,以及其他训练中的非参数SIRD模型。
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Accurate determination of a small molecule candidate (ligand) binding pose in its target protein pocket is important for computer-aided drug discovery. Typical rigid-body docking methods ignore the pocket flexibility of protein, while the more accurate pose generation using molecular dynamics is hindered by slow protein dynamics. We develop a tiered tensor transform (3T) algorithm to rapidly generate diverse protein-ligand complex conformations for both pose and affinity estimation in drug screening, requiring neither machine learning training nor lengthy dynamics computation, while maintaining both coarse-grain-like coordinated protein dynamics and atomistic-level details of the complex pocket. The 3T conformation structures we generate are closer to experimental co-crystal structures than those generated by docking software, and more importantly achieve significantly higher accuracy in active ligand classification than traditional ensemble docking using hundreds of experimental protein conformations. 3T structure transformation is decoupled from the system physics, making future usage in other computational scientific domains possible.
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Adversarial imitation learning (AIL) has become a popular alternative to supervised imitation learning that reduces the distribution shift suffered by the latter. However, AIL requires effective exploration during an online reinforcement learning phase. In this work, we show that the standard, naive approach to exploration can manifest as a suboptimal local maximum if a policy learned with AIL sufficiently matches the expert distribution without fully learning the desired task. This can be particularly catastrophic for manipulation tasks, where the difference between an expert and a non-expert state-action pair is often subtle. We present Learning from Guided Play (LfGP), a framework in which we leverage expert demonstrations of multiple exploratory, auxiliary tasks in addition to a main task. The addition of these auxiliary tasks forces the agent to explore states and actions that standard AIL may learn to ignore. Additionally, this particular formulation allows for the reusability of expert data between main tasks. Our experimental results in a challenging multitask robotic manipulation domain indicate that LfGP significantly outperforms both AIL and behaviour cloning, while also being more expert sample efficient than these baselines. To explain this performance gap, we provide further analysis of a toy problem that highlights the coupling between a local maximum and poor exploration, and also visualize the differences between the learned models from AIL and LfGP.
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Many problems in machine learning involve bilevel optimization (BLO), including hyperparameter optimization, meta-learning, and dataset distillation. Bilevel problems consist of two nested sub-problems, called the outer and inner problems, respectively. In practice, often at least one of these sub-problems is overparameterized. In this case, there are many ways to choose among optima that achieve equivalent objective values. Inspired by recent studies of the implicit bias induced by optimization algorithms in single-level optimization, we investigate the implicit bias of gradient-based algorithms for bilevel optimization. We delineate two standard BLO methods -- cold-start and warm-start -- and show that the converged solution or long-run behavior depends to a large degree on these and other algorithmic choices, such as the hypergradient approximation. We also show that the inner solutions obtained by warm-start BLO can encode a surprising amount of information about the outer objective, even when the outer parameters are low-dimensional. We believe that implicit bias deserves as central a role in the study of bilevel optimization as it has attained in the study of single-level neural net optimization.
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