我们研究依靠敏感数据（例如医疗记录）的环境的顺序决策中，研究隐私的探索。特别是，我们专注于解决在线性MDP设置中受（联合）差异隐私的约束的增强学习问题（RL），在该设置中，动态和奖励均由线性函数给出。由于Luyo等人而引起的此问题的事先工作。 （2021）实现了$ o（k^{3/5}）$的依赖性的遗憾率。我们提供了一种私人算法，其遗憾率提高，最佳依赖性为$ o（\ sqrt {k}）$对情节数量。我们强烈遗憾保证的关键配方是策略更新时间表中的适应性，其中仅在检测到数据足够更改时才发生更新。结果，我们的算法受益于低切换成本，并且仅执行$ o（\ log（k））$更新，这大大降低了隐私噪声的量。最后，在最普遍的隐私制度中，隐私参数$ \ epsilon $是一个常数，我们的算法会造成可忽略不计的隐私成本 - 与现有的非私人遗憾界限相比，由于隐私而引起的额外遗憾在低阶中出现了术语。

表示技术的快速发展和大规模医学成像数据的可用性必须在3D医学图像分析中快速增加机器学习的使用。特别是，深度卷积神经网络（D-CNN）是关键参与者，并被医学成像界采用，以协助临床医生和医学专家进行疾病诊断。然而，培训深层神经网络，例如在高分辨率3D体积的计算机断层扫描（CT）扫描中进行诊断任务的D-CNN带来了强大的计算挑战。这提出了开发基于深度学习的方法，这些方法在2D图像中具有强大的学习表示形式，而是3D扫描。在本文中，我们提出了一种新的策略，以根据沿轴的相邻切片的描述来训练CT扫描上的\ emph {slice level}分类器。特别是，每一个都是通过卷积神经网络（CNN）提取的。该方法适用于具有每片标签的CT数据集，例如RSNA颅内出血（ICH）数据集，该数据集旨在预测ICH的存在并将其分类为5个不同的子类型。我们在RSNA ICH挑战的最佳4 \％最佳解决方案中获得了单个模型，其中允许模型集成。实验还表明，所提出的方法显着优于CQ500上的基线模型。所提出的方法是一般的，可以应用于其他3D医学诊断任务，例如MRI成像。为了鼓励该领域的新进步，我们将在接受论文后制定我们的代码和预培训模型。

在机器学习（ML）算法自动化或提供有关人员的后果决策的环境中，通常会激励个人决策主题以战略性地修改其可观察的属性以获得更有利的预测。结果，对评估规则进行培训的分布可能与其部署中运营的规则不同。尽管这种分配的变化通常可以阻碍准确的预测，但我们的工作确定了由于战略反应而引起的转变相关的独特机会：我们表明我们可以有效地利用战略反应来恢复可观察到的特征与我们希望预测的可观察到的因果关系，即使在没有观察到的混杂变量的情况下。具体而言，我们的工作通过观察到部署模型的序列可以看作是影响代理可观察到的特征但不会直接影响其结果的工具，从而建立了对ML模型的战略响应与仪器变量（IV）回归之间的新颖联系。我们表明，我们的因果恢复方法可用于改善几个重要标准的决策：个人公平，代理结果和预测风险。特别是，我们表明，如果决策主体在修改非毒物属性的能力上有所不同，那么与因果系数偏离的任何决策规则都可能导致（潜在无限）个体级别的不公平性。

The performance of inertial navigation systems is largely dependent on the stable flow of external measurements and information to guarantee continuous filter updates and bind the inertial solution drift. Platforms in different operational environments may be prevented at some point from receiving external measurements, thus exposing their navigation solution to drift. Over the years, a wide variety of works have been proposed to overcome this shortcoming, by exploiting knowledge of the system current conditions and turning it into an applicable source of information to update the navigation filter. This paper aims to provide an extensive survey of information aided navigation, broadly classified into direct, indirect, and model aiding. Each approach is described by the notable works that implemented its concept, use cases, relevant state updates, and their corresponding measurement models. By matching the appropriate constraint to a given scenario, one will be able to improve the navigation solution accuracy, compensate for the lost information, and uncover certain internal states, that would otherwise remain unobservable.

We consider infinite horizon Markov decision processes (MDPs) with fast-slow structure, meaning that certain parts of the state space move "fast" (and in a sense, are more influential) while other parts transition more "slowly." Such structure is common in real-world problems where sequential decisions need to be made at high frequencies, yet information that varies at a slower timescale also influences the optimal policy. Examples include: (1) service allocation for a multi-class queue with (slowly varying) stochastic costs, (2) a restless multi-armed bandit with an environmental state, and (3) energy demand response, where both day-ahead and real-time prices play a role in the firm's revenue. Models that fully capture these problems often result in MDPs with large state spaces and large effective time horizons (due to frequent decisions), rendering them computationally intractable. We propose an approximate dynamic programming algorithmic framework based on the idea of "freezing" the slow states, solving a set of simpler finite-horizon MDPs (the lower-level MDPs), and applying value iteration (VI) to an auxiliary MDP that transitions on a slower timescale (the upper-level MDP). We also extend the technique to a function approximation setting, where a feature-based linear architecture is used. On the theoretical side, we analyze the regret incurred by each variant of our frozen-state approach. Finally, we give empirical evidence that the frozen-state approach generates effective policies using just a fraction of the computational cost, while illustrating that simply omitting slow states from the decision modeling is often not a viable heuristic.

In the present work we propose an unsupervised ensemble method consisting of oblique trees that can address the task of auto-encoding, namely Oblique Forest AutoEncoders (briefly OF-AE). Our method is a natural extension of the eForest encoder introduced in [1]. More precisely, by employing oblique splits consisting in multivariate linear combination of features instead of the axis-parallel ones, we will devise an auto-encoder method through the computation of a sparse solution of a set of linear inequalities consisting of feature values constraints. The code for reproducing our results is available at https://github.com/CDAlecsa/Oblique-Forest-AutoEncoders.

When robots learn reward functions using high capacity models that take raw state directly as input, they need to both learn a representation for what matters in the task -- the task ``features" -- as well as how to combine these features into a single objective. If they try to do both at once from input designed to teach the full reward function, it is easy to end up with a representation that contains spurious correlations in the data, which fails to generalize to new settings. Instead, our ultimate goal is to enable robots to identify and isolate the causal features that people actually care about and use when they represent states and behavior. Our idea is that we can tune into this representation by asking users what behaviors they consider similar: behaviors will be similar if the features that matter are similar, even if low-level behavior is different; conversely, behaviors will be different if even one of the features that matter differs. This, in turn, is what enables the robot to disambiguate between what needs to go into the representation versus what is spurious, as well as what aspects of behavior can be compressed together versus not. The notion of learning representations based on similarity has a nice parallel in contrastive learning, a self-supervised representation learning technique that maps visually similar data points to similar embeddings, where similarity is defined by a designer through data augmentation heuristics. By contrast, in order to learn the representations that people use, so we can learn their preferences and objectives, we use their definition of similarity. In simulation as well as in a user study, we show that learning through such similarity queries leads to representations that, while far from perfect, are indeed more generalizable than self-supervised and task-input alternatives.

While the capabilities of autonomous systems have been steadily improving in recent years, these systems still struggle to rapidly explore previously unknown environments without the aid of GPS-assisted navigation. The DARPA Subterranean (SubT) Challenge aimed to fast track the development of autonomous exploration systems by evaluating their performance in real-world underground search-and-rescue scenarios. Subterranean environments present a plethora of challenges for robotic systems, such as limited communications, complex topology, visually-degraded sensing, and harsh terrain. The presented solution enables long-term autonomy with minimal human supervision by combining a powerful and independent single-agent autonomy stack, with higher level mission management operating over a flexible mesh network. The autonomy suite deployed on quadruped and wheeled robots was fully independent, freeing the human supervision to loosely supervise the mission and make high-impact strategic decisions. We also discuss lessons learned from fielding our system at the SubT Final Event, relating to vehicle versatility, system adaptability, and re-configurable communications.

Deep learning models are known to put the privacy of their training data at risk, which poses challenges for their safe and ethical release to the public. Differentially private stochastic gradient descent is the de facto standard for training neural networks without leaking sensitive information about the training data. However, applying it to models for graph-structured data poses a novel challenge: unlike with i.i.d. data, sensitive information about a node in a graph cannot only leak through its gradients, but also through the gradients of all nodes within a larger neighborhood. In practice, this limits privacy-preserving deep learning on graphs to very shallow graph neural networks. We propose to solve this issue by training graph neural networks on disjoint subgraphs of a given training graph. We develop three random-walk-based methods for generating such disjoint subgraphs and perform a careful analysis of the data-generating distributions to provide strong privacy guarantees. Through extensive experiments, we show that our method greatly outperforms the state-of-the-art baseline on three large graphs, and matches or outperforms it on four smaller ones.

Machine learning models are typically evaluated by computing similarity with reference annotations and trained by maximizing similarity with such. Especially in the bio-medical domain, annotations are subjective and suffer from low inter- and intra-rater reliability. Since annotations only reflect the annotation entity's interpretation of the real world, this can lead to sub-optimal predictions even though the model achieves high similarity scores. Here, the theoretical concept of Peak Ground Truth (PGT) is introduced. PGT marks the point beyond which an increase in similarity with the reference annotation stops translating to better Real World Model Performance (RWMP). Additionally, a quantitative technique to approximate PGT by computing inter- and intra-rater reliability is proposed. Finally, three categories of PGT-aware strategies to evaluate and improve model performance are reviewed.