We investigate how effective an attacker can be when it only learns from its victim's actions, without access to the victim's reward. In this work, we are motivated by the scenario where the attacker wants to behave strategically when the victim's motivations are unknown. We argue that one heuristic approach an attacker can use is to maximize the entropy of the victim's policy. The policy is generally not obfuscated, which implies it may be extracted simply by passively observing the victim. We provide such a strategy in the form of a reward-free exploration algorithm that maximizes the attacker's entropy during the exploration phase, and then maximizes the victim's empirical entropy during the planning phase. In our experiments, the victim agents are subverted through policy entropy maximization, implying an attacker might not need access to the victim's reward to succeed. Hence, reward-free attacks, which are based only on observing behavior, show the feasibility of an attacker to act strategically without knowledge of the victim's motives even if the victim's reward information is protected.

The medical automatic diagnosis system aims to imitate human doctors in the real diagnostic process. This task is formulated as a sequential decision-making problem with symptom inquiring and disease diagnosis. In recent years, many researchers have used reinforcement learning methods to handle this task. However, most recent works neglected to distinguish the symptom inquiring and disease diagnosing actions and mixed them into one action space. This results in the unsatisfactory performance of reinforcement learning methods on this task. Moreover, there is a lack of a public evaluation dataset that contains various diseases and corresponding information. To address these issues, we first propose a novel method for medical automatic diagnosis with symptom inquiring and disease diagnosing formulated as a reinforcement learning task and a classification task, respectively. We also propose a robust and adaptive method to align the two tasks using distribution entropies as media. Then, we create a new dataset extracted from the MedlinePlus knowledge base. The dataset contains more diseases and more complete symptom information. The simulated patients for experiments are more realistic. Experimental evaluation results show that our method outperforms three recent state-of-the-art methods on different datasets by achieving higher medical diagnosis accuracies with few inquiring turns.

The continuous electrification of the mobility and heating sectors adds much-needed flexibility to the power system. However, flexibility utilization also introduces new challenges to distribution system operators (DSOs), who need mechanisms to supervise flexibility activations and monitor their effect on distribution network operation. Flexibility activations can be broadly categorized to those originating from electricity markets and those initiated by the DSO to avoid constraint violations. Simultaneous electricity market driven flexibility activations may cause voltage quality or temporary overloading issues, and the failure of flexibility activations initiated by the DSO might leave critical grid states unresolved. This work proposes a novel data processing pipeline for automated real-time identification of fast-ramped flexibility activation events. Its practical value is twofold: i) potentially critical flexibility activations originating from electricity markets can be detected by the DSO at an early stage, and ii) successful activation of DSO-requested flexibility can be verified by the operator. In both cases the increased awareness would allow the DSO to take counteractions to avoid potentially critical grid situations. The proposed pipeline combines techniques from unsupervised detection and open-set classification. For both building blocks feasibility is systematically evaluated and proofed on real load and flexibility activation data.

Meta-reinforcement learning (meta-RL) has proven to be a successful framework for leveraging experience from prior tasks to rapidly learn new related tasks, however, current meta-RL approaches struggle to learn in sparse reward environments. Although existing meta-RL algorithms can learn strategies for adapting to new sparse reward tasks, the actual adaptation strategies are learned using hand-shaped reward functions, or require simple environments where random exploration is sufficient to encounter sparse reward. In this paper, we present a formulation of hindsight relabeling for meta-RL, which relabels experience during meta-training to enable learning to learn entirely using sparse reward. We demonstrate the effectiveness of our approach on a suite of challenging sparse reward goal-reaching environments that previously required dense reward during meta-training to solve. Our approach solves these environments using the true sparse reward function, with performance comparable to training with a proxy dense reward function.

Consistency is the theoretical property of a meta learning algorithm that ensures that, under certain assumptions, it can adapt to any task at test time. An open question is whether and how theoretical consistency translates into practice, in comparison to inconsistent algorithms. In this paper, we empirically investigate this question on a set of representative meta-RL algorithms. We find that theoretically consistent algorithms can indeed usually adapt to out-of-distribution (OOD) tasks, while inconsistent ones cannot, although they can still fail in practice for reasons like poor exploration. We further find that theoretically inconsistent algorithms can be made consistent by continuing to update all agent components on the OOD tasks, and adapt as well or better than originally consistent ones. We conclude that theoretical consistency is indeed a desirable property, and inconsistent meta-RL algorithms can easily be made consistent to enjoy the same benefits.

In many sequential decision-making problems (e.g., robotics control, game playing, sequential prediction), human or expert data is available containing useful information about the task. However, imitation learning (IL) from a small amount of expert data can be challenging in high-dimensional environments with complex dynamics. Behavioral cloning is a simple method that is widely used due to its simplicity of implementation and stable convergence but doesn't utilize any information involving the environment's dynamics. Many existing methods that exploit dynamics information are difficult to train in practice due to an adversarial optimization process over reward and policy approximators or biased, high variance gradient estimators. We introduce a method for dynamics-aware IL which avoids adversarial training by learning a single Q-function, implicitly representing both reward and policy. On standard benchmarks, the implicitly learned rewards show a high positive correlation with the ground-truth rewards, illustrating our method can also be used for inverse reinforcement learning (IRL). Our method, Inverse soft-Q learning (IQ-Learn) obtains state-of-the-art results in offline and online imitation learning settings, significantly outperforming existing methods both in the number of required environment interactions and scalability in high-dimensional spaces, often by more than 3x.

Tactics analyze the current proof state (goal and assumptions) and apply non-trivial proof transformations. Formalized proofs take advantage of different levels of automation which are in increasing order of generality: specialized rules, theory-based strategies and general purpose strategies. Thanks to progress in proof automation, developers can delegate more and more complicated proof obligations to general purpose strategies. Those are implemented by automated theorem provers (ATPs) such as E prover [32]. Communication between an ITP and ATPs is made possible by a "hammer" system [4,14]. It acts as an interface by performing premise selection, translation and proof reconstruction. Yet, ATPs are not flawless and more precise user-guidance, achieved by applying a particular sequence of specialized rules, is almost always necessary to develop a mathematical theory.

Changing the Ashes schedule to include a second pink-ball Test would give England an advantage, says former Australia bowler Mitchell Johnson.

Clearview AI is back in hot water, this time from the UK's Information Commissioner's Office (ICO). The controversial facial recognition giant has caught the attention of global privacy regulators and campaigners for its practice of scraping personal photos from the web for its system without explicit consent. Clearview AI is expected to have scraped over 10 billion photos. "Common law has never recognised a right to privacy for your face," Clearview AI lawyer Tor Ekeland once argued. The UK's ICO launched a joint probe with the Office of the Australian Information Commissioner (OAIC) into Cleaview AI's practices. Earlier this month, Australia's Information Commissioner Angelene Falk determined that "the act of uploading an image to a social media site does not unambiguously indicate agreement to collection of that image by an unknown third party for commercial purposes."

The UK's Information Commissioner's Office (ICO) has provisionally fined the facial recognition company Clearview AI £17 million ($22.6 million) for breaching UK data protection laws. It said that Clearview allegedly failed to inform citizens that it was collecting billions of their photos, among other transgressions. It has also (again, provisionally) ordered it to stop further processing of residents' personal data. The regulator said that Clearview apparently failed to process people's data "in a way that they likely expect or that is fair." It also alleged that the company failed to have a lawful reason to collect the data, didn't meet GDPR standards for biometric data, failed to have a process that prevents data from being retained indefinitely and failed to inform UK residents what was happening to their data.