在机器学习中的解释性的重要性继续增长,因为神经网络架构和它们模型的数据变得越来越复杂。当模型的输入功能变为高维时,出现独特的挑战:一方面,解释性的原则性模型可靠性方法变得过于计算昂贵;另一方面,更高效的解释性算法缺乏对普通用户的自然解释。在这项工作中,我们在高维数据上介绍了用于人类可解释的解释性的框架,由两个模块组成。首先,我们应用一个语义上有意义的潜在表示,以降低数据的原始维度,并确保其人的解释性。可以学习这些潜在的特征,例如,通过图像到图像转换明确地解散表示或隐含地解散表示,或者它们可以基于用户选择的任何可计算量。其次,我们适应福利范式以进行模型 - 无人释放能力,以在这些潜在特征上运行。这导致理论上控制和计算易解释的可解释模型解释。我们在合成数据上基准测试我们的方法,并展示其对几种图像分类任务的效果。
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AI中的解释性对于模型开发,遵守规则并提供对预测的操作细微差异至关重要。 Shapley框架解释性地将模型的预测以数学上的原则和模型无话的方式对其输入特征属性。然而,福利释放性的一般实施使得一个无法维持的假设:模型的功能是不相关的。在这项工作中,我们展示了这种假设的明确缺点,并开发了两个对围绕数据歧管的福利解释性的解决方案。基于生成建模的一种解决方案提供了对数据避难所的灵活访问;另一种直接学习福利价值功能,以灵活成本提供性能和稳定性。虽然“偏流”福谢值(i)产生不正确的解释,但是(ii)隐藏对敏感属性的隐式模型依赖性,并且(iii)导致在高维数据中的解释,歧管解释性克服了这些问题。
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解释AI系统是对高性能模型的发展以及由用户放置在其中的信任的基础。福利框架可解释性具有强大的普遍适用性,结合其精确,严谨的基础:它为AI解释性提供了一种常见的模型 - 不可知论性,并且唯一满足一组直观的数学公理。但是,福利值在一个重要方面过于限制:它们忽略了数据中的所有因果结构。我们介绍了一种更少的限制性框架,不对称的福利值(ASV),其严格地建立在一组公理上,适用于任何AI系统,并且足够灵活地融合已知数据所遵守的任何因果结构。我们证明ASVS可以(i)通过结合因果信息来改善模型解释,(ii)在模型预测中提供不公平歧视的明确测试,(iii)在时间序列模型中顺序增量解释,(iv)支持特征 - 无需模型再培训的选择研究。
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We present a dynamic path planning algorithm to navigate an amphibious rotor craft through a concave time-invariant obstacle field while attempting to minimize energy usage. We create a nonlinear quaternion state model that represents the rotor craft dynamics above and below the water. The 6 degree of freedom dynamics used within a layered architecture to generate motion paths for the vehicle to follow and the required control inputs. The rotor craft has a 3 dimensional map of its surroundings that is updated via limited range onboard sensor readings within the current medium (air or water). Path planning is done via PRM and D* Lite.
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Biological systems often choose actions without an explicit reward signal, a phenomenon known as intrinsic motivation. The computational principles underlying this behavior remain poorly understood. In this study, we investigate an information-theoretic approach to intrinsic motivation, based on maximizing an agent's empowerment (the mutual information between its past actions and future states). We show that this approach generalizes previous attempts to formalize intrinsic motivation, and we provide a computationally efficient algorithm for computing the necessary quantities. We test our approach on several benchmark control problems, and we explain its success in guiding intrinsically motivated behaviors by relating our information-theoretic control function to fundamental properties of the dynamical system representing the combined agent-environment system. This opens the door for designing practical artificial, intrinsically motivated controllers and for linking animal behaviors to their dynamical properties.
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Modern mobile burst photography pipelines capture and merge a short sequence of frames to recover an enhanced image, but often disregard the 3D nature of the scene they capture, treating pixel motion between images as a 2D aggregation problem. We show that in a "long-burst", forty-two 12-megapixel RAW frames captured in a two-second sequence, there is enough parallax information from natural hand tremor alone to recover high-quality scene depth. To this end, we devise a test-time optimization approach that fits a neural RGB-D representation to long-burst data and simultaneously estimates scene depth and camera motion. Our plane plus depth model is trained end-to-end, and performs coarse-to-fine refinement by controlling which multi-resolution volume features the network has access to at what time during training. We validate the method experimentally, and demonstrate geometrically accurate depth reconstructions with no additional hardware or separate data pre-processing and pose-estimation steps.
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Reinforcement learning can enable robots to navigate to distant goals while optimizing user-specified reward functions, including preferences for following lanes, staying on paved paths, or avoiding freshly mowed grass. However, online learning from trial-and-error for real-world robots is logistically challenging, and methods that instead can utilize existing datasets of robotic navigation data could be significantly more scalable and enable broader generalization. In this paper, we present ReViND, the first offline RL system for robotic navigation that can leverage previously collected data to optimize user-specified reward functions in the real-world. We evaluate our system for off-road navigation without any additional data collection or fine-tuning, and show that it can navigate to distant goals using only offline training from this dataset, and exhibit behaviors that qualitatively differ based on the user-specified reward function.
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Recent advances in batch (offline) reinforcement learning have shown promising results in learning from available offline data and proved offline reinforcement learning to be an essential toolkit in learning control policies in a model-free setting. An offline reinforcement learning algorithm applied to a dataset collected by a suboptimal non-learning-based algorithm can result in a policy that outperforms the behavior agent used to collect the data. Such a scenario is frequent in robotics, where existing automation is collecting operational data. Although offline learning techniques can learn from data generated by a sub-optimal behavior agent, there is still an opportunity to improve the sample complexity of existing offline reinforcement learning algorithms by strategically introducing human demonstration data into the training process. To this end, we propose a novel approach that uses uncertainty estimation to trigger the injection of human demonstration data and guide policy training towards optimal behavior while reducing overall sample complexity. Our experiments show that this approach is more sample efficient when compared to a naive way of combining expert data with data collected from a sub-optimal agent. We augmented an existing offline reinforcement learning algorithm Conservative Q-Learning with our approach and performed experiments on data collected from MuJoCo and OffWorld Gym learning environments.
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Monitoring changes inside a reservoir in real time is crucial for the success of CO2 injection and long-term storage. Machine learning (ML) is well-suited for real-time CO2 monitoring because of its computational efficiency. However, most existing applications of ML yield only one prediction (i.e., the expectation) for a given input, which may not properly reflect the distribution of the testing data, if it has a shift with respect to that of the training data. The Simultaneous Quantile Regression (SQR) method can estimate the entire conditional distribution of the target variable of a neural network via pinball loss. Here, we incorporate this technique into seismic inversion for purposes of CO2 monitoring. The uncertainty map is then calculated pixel by pixel from a particular prediction interval around the median. We also propose a novel data-augmentation method by sampling the uncertainty to further improve prediction accuracy. The developed methodology is tested on synthetic Kimberlina data, which are created by the Department of Energy and based on a CO2 capture and sequestration (CCS) project in California. The results prove that the proposed network can estimate the subsurface velocity rapidly and with sufficient resolution. Furthermore, the computed uncertainty quantifies the prediction accuracy. The method remains robust even if the testing data are distorted due to problems in the field data acquisition. Another test demonstrates the effectiveness of the developed data-augmentation method in increasing the spatial resolution of the estimated velocity field and in reducing the prediction error.
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Stacking (or stacked generalization) is an ensemble learning method with one main distinctiveness from the rest: even though several base models are trained on the original data set, their predictions are further used as input data for one or more metamodels arranged in at least one extra layer. Composing a stack of models can produce high-performance outcomes, but it usually involves a trial-and-error process. Therefore, our previously developed visual analytics system, StackGenVis, was mainly designed to assist users in choosing a set of top-performing and diverse models by measuring their predictive performance. However, it only employs a single logistic regression metamodel. In this paper, we investigate the impact of alternative metamodels on the performance of stacking ensembles using a novel visualization tool, called MetaStackVis. Our interactive tool helps users to visually explore different singular and pairs of metamodels according to their predictive probabilities and multiple validation metrics, as well as their ability to predict specific problematic data instances. MetaStackVis was evaluated with a usage scenario based on a medical data set and via expert interviews.
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