预训练的语言模型的目的是学习文本数据的上下文表示。预训练的语言模型已成为自然语言处理和代码建模的主流。使用探针，一种研究隐藏矢量空间的语言特性的技术，以前的作品表明，这些预训练的语言模型在其隐藏表示中编码简单的语言特性。但是，以前的工作都没有评估这些模型是否编码编程语言的整个语法结构。在本文中，我们证明了\ textit {句法子空间}的存在，该{语法子空间}位于预训练的语言模型的隐藏表示中，其中包含编程语言的句法信息。我们表明，可以从模型的表示形式中提取此子空间，并定义一种新颖的探测方法AST-Probe，该方法可以恢复输入代码段的整个抽象语法树（AST）。在我们的实验中，我们表明这种句法子空间存在于五个最先进的预训练的语言模型中。此外，我们强调说，模型的中间层是编码大多数AST信息的模型。最后，我们估计该句法子空间的最佳大小，并表明其尺寸大大低于模型的表示空间。这表明，预训练的语言模型使用其表示空间的一小部分来编码编程语言的句法信息。

In the last years, the number of IoT devices deployed has suffered an undoubted explosion, reaching the scale of billions. However, some new cybersecurity issues have appeared together with this development. Some of these issues are the deployment of unauthorized devices, malicious code modification, malware deployment, or vulnerability exploitation. This fact has motivated the requirement for new device identification mechanisms based on behavior monitoring. Besides, these solutions have recently leveraged Machine and Deep Learning techniques due to the advances in this field and the increase in processing capabilities. In contrast, attackers do not stay stalled and have developed adversarial attacks focused on context modification and ML/DL evaluation evasion applied to IoT device identification solutions. This work explores the performance of hardware behavior-based individual device identification, how it is affected by possible context- and ML/DL-focused attacks, and how its resilience can be improved using defense techniques. In this sense, it proposes an LSTM-CNN architecture based on hardware performance behavior for individual device identification. Then, previous techniques have been compared with the proposed architecture using a hardware performance dataset collected from 45 Raspberry Pi devices running identical software. The LSTM-CNN improves previous solutions achieving a +0.96 average F1-Score and 0.8 minimum TPR for all devices. Afterward, context- and ML/DL-focused adversarial attacks were applied against the previous model to test its robustness. A temperature-based context attack was not able to disrupt the identification. However, some ML/DL state-of-the-art evasion attacks were successful. Finally, adversarial training and model distillation defense techniques are selected to improve the model resilience to evasion attacks, without degrading its performance.

Cybercriminals are moving towards zero-day attacks affecting resource-constrained devices such as single-board computers (SBC). Assuming that perfect security is unrealistic, Moving Target Defense (MTD) is a promising approach to mitigate attacks by dynamically altering target attack surfaces. Still, selecting suitable MTD techniques for zero-day attacks is an open challenge. Reinforcement Learning (RL) could be an effective approach to optimize the MTD selection through trial and error, but the literature fails when i) evaluating the performance of RL and MTD solutions in real-world scenarios, ii) studying whether behavioral fingerprinting is suitable for representing SBC's states, and iii) calculating the consumption of resources in SBC. To improve these limitations, the work at hand proposes an online RL-based framework to learn the correct MTD mechanisms mitigating heterogeneous zero-day attacks in SBC. The framework considers behavioral fingerprinting to represent SBCs' states and RL to learn MTD techniques that mitigate each malicious state. It has been deployed on a real IoT crowdsensing scenario with a Raspberry Pi acting as a spectrum sensor. More in detail, the Raspberry Pi has been infected with different samples of command and control malware, rootkits, and ransomware to later select between four existing MTD techniques. A set of experiments demonstrated the suitability of the framework to learn proper MTD techniques mitigating all attacks (except a harmfulness rootkit) while consuming <1 MB of storage and utilizing <55% CPU and <80% RAM.

Spacecraft pose estimation is a key task to enable space missions in which two spacecrafts must navigate around each other. Current state-of-the-art algorithms for pose estimation employ data-driven techniques. However, there is an absence of real training data for spacecraft imaged in space conditions due to the costs and difficulties associated with the space environment. This has motivated the introduction of 3D data simulators, solving the issue of data availability but introducing a large gap between the training (source) and test (target) domains. We explore a method that incorporates 3D structure into the spacecraft pose estimation pipeline to provide robustness to intensity domain shift and we present an algorithm for unsupervised domain adaptation with robust pseudo-labelling. Our solution has ranked second in the two categories of the 2021 Pose Estimation Challenge organised by the European Space Agency and the Stanford University, achieving the lowest average error over the two categories.

Privacy-preserving machine learning in data-sharing processes is an ever-critical task that enables collaborative training of Machine Learning (ML) models without the need to share the original data sources. It is especially relevant when an organization must assure that sensitive data remains private throughout the whole ML pipeline, i.e., training and inference phases. This paper presents an innovative framework that uses Representation Learning via autoencoders to generate privacy-preserving embedded data. Thus, organizations can share the data representation to increase machine learning models' performance in scenarios with more than one data source for a shared predictive downstream task.

In this work, we propose a framework relying solely on chat-based customer support (CS) interactions for predicting the recommendation decision of individual users. For our case study, we analyzed a total number of 16.4k users and 48.7k customer support conversations within the financial vertical of a large e-commerce company in Latin America. Consequently, our main contributions and objectives are to use Natural Language Processing (NLP) to assess and predict the recommendation behavior where, in addition to using static sentiment analysis, we exploit the predictive power of each user's sentiment dynamics. Our results show that, with respective feature interpretability, it is possible to predict the likelihood of a user to recommend a product or service, based solely on the message-wise sentiment evolution of their CS conversations in a fully automated way.

We present the GPry algorithm for fast Bayesian inference of general (non-Gaussian) posteriors with a moderate number of parameters. GPry does not need any pre-training, special hardware such as GPUs, and is intended as a drop-in replacement for traditional Monte Carlo methods for Bayesian inference. Our algorithm is based on generating a Gaussian Process surrogate model of the log-posterior, aided by a Support Vector Machine classifier that excludes extreme or non-finite values. An active learning scheme allows us to reduce the number of required posterior evaluations by two orders of magnitude compared to traditional Monte Carlo inference. Our algorithm allows for parallel evaluations of the posterior at optimal locations, further reducing wall-clock times. We significantly improve performance using properties of the posterior in our active learning scheme and for the definition of the GP prior. In particular we account for the expected dynamical range of the posterior in different dimensionalities. We test our model against a number of synthetic and cosmological examples. GPry outperforms traditional Monte Carlo methods when the evaluation time of the likelihood (or the calculation of theoretical observables) is of the order of seconds; for evaluation times of over a minute it can perform inference in days that would take months using traditional methods. GPry is distributed as an open source Python package (pip install gpry) and can also be found at https://github.com/jonaselgammal/GPry.

社会互动网络是建立文明的基材。通常，我们与我们喜欢的人建立新的纽带，或者认为通过第三方的干预，我们的关系损害了。尽管它们的重要性和这些过程对我们的生活产生的巨大影响，但对它们的定量科学理解仍处于起步阶段，这主要是由于很难收集大量的社交网络数据集，包括个人属性。在这项工作中，我们对13所学校的真实社交网络进行了彻底的研究，其中3,000多名学生和60,000名宣布正面关系和负面关系，包括对所有学生的个人特征的测试。我们引入了一个度量标准 - “三合会影响”，该指标衡量了最近的邻居在其接触关系中的影响。我们使用神经网络来预测关系，并根据他们的个人属性或三合会的影响来提取两个学生是朋友或敌人的可能性。或者，我们可以使用网络结构的高维嵌入来预测关系。值得注意的是，三合会影响（一个简单的一维度量）在预测两个学生之间的关系方面达到了最高的准确性。我们假设从神经网络中提取的概率 - 三合会影响的功能和学生的个性 - 控制真实社交网络的演变，为这些系统的定量研究开辟了新的途径。

社交媒体数据已成为有关现实世界危机事件的及时信息的有用来源。与将社交媒体用于灾难管理有关的主要任务之一是自动识别与危机相关的消息。关于该主题的大多数研究都集中在特定语言中特定类型事件的数据分析上。这限制了概括现有方法的可能性，因为模型不能直接应用于新类型的事件或其他语言。在这项工作中，我们研究了通过利用跨语言和跨域标记数据来自动对与危机事件相关的消息进行分类的任务。我们的目标是利用来自高资源语言的标记数据来对其他（低资源）语言和/或新（以前看不见的）类型的危机情况进行分类。在我们的研究中，我们从文献中合并了一个大型统一数据集，其中包含多个危机事件和语言。我们的经验发现表明，确实有可能利用英语危机事件的数据来对其他语言（例如西班牙语和意大利语）（80.0％的F1得分）对相同类型的事件进行分类。此外，我们在跨语言环境中为跨域任务（80.0％F1得分）取得了良好的性能。总体而言，我们的工作有助于改善数据稀缺问题，这对于多语言危机分类非常重要。特别是，当时间是本质的时候，可以减轻紧急事件中的冷启动情况。

可以通过玩游戏来训练代理商来回答困难的数学问题吗？我们考虑了整数可行性问题，这是决定线性方程和不平等系统是否具有具有整数值的解决方案的挑战。对于许多数学和计算机科学领域的应用，这是一个著名的NP完整问题。我们的论文描述了一个新颖的代数增强学习框架，该框架使代理商可以玩相当于整数可行性问题的游戏。我们解释了如何将整数可行性问题转换为具有固定保证金总和的一组阵列的游戏。游戏从初始状态（数组）开始，并采取法律举措使利润率保持不变，我们的目标是最终与零位置的零位置达到胜利状态。为了赢得比赛，玩家必须在初始状态和最终终端获胜状态之间找到一条路径。找到这样的获胜状态等同于解决整数可行性问题。关键代数成分是“基础轴向运输polyhedron的曲折理想的基础”。gr \'obner可以看作是游戏的一组连接移动（动作）。然后，我们提出了一种新型的RL方法，该方法训练代理以预测连续空间中的移动，以应对较大的动作空间。然后将连续的移动投射到一组法律移动上，以使该路径始终导致有效状态。作为概念的证明，我们在实验中证明了我们的代理商可以很好地发挥我们最简单的游戏版本，用于2向表。我们的工作突出了培训代理商通过当代机器学习方法来训练代理商玩游戏的潜力来解决非平凡的数学查询的潜力。