Zero-sum Markov Games (MGs) has been an efficient framework for multi-agent systems and robust control, wherein a minimax problem is constructed to solve the equilibrium policies. At present, this formulation is well studied under tabular settings wherein the maximum operator is primarily and exactly solved to calculate the worst-case value function. However, it is non-trivial to extend such methods to handle complex tasks, as finding the maximum over large-scale action spaces is usually cumbersome. In this paper, we propose the smoothing policy iteration (SPI) algorithm to solve the zero-sum MGs approximately, where the maximum operator is replaced by the weighted LogSumExp (WLSE) function to obtain the nearly optimal equilibrium policies. Specially, the adversarial policy is served as the weight function to enable an efficient sampling over action spaces.We also prove the convergence of SPI and analyze its approximation error in $\infty -$norm based on the contraction mapping theorem. Besides, we propose a model-based algorithm called Smooth adversarial Actor-critic (SaAC) by extending SPI with the function approximations. The target value related to WLSE function is evaluated by the sampled trajectories and then mean square error is constructed to optimize the value function, and the gradient-ascent-descent methods are adopted to optimize the protagonist and adversarial policies jointly. In addition, we incorporate the reparameterization technique in model-based gradient back-propagation to prevent the gradient vanishing due to sampling from the stochastic policies. We verify our algorithm in both tabular and function approximation settings. Results show that SPI can approximate the worst-case value function with a high accuracy and SaAC can stabilize the training process and improve the adversarial robustness in a large margin.
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In the field of antibody engineering, an essential task is to design a novel antibody whose paratopes bind to a specific antigen with correct epitopes. Understanding antibody structure and its paratope can facilitate a mechanistic understanding of its function. Therefore, antibody structure prediction from its sequence alone has always been a highly valuable problem for de novo antibody design. AlphaFold2, a breakthrough in the field of structural biology, provides a solution to predict protein structure based on protein sequences and computationally expensive coevolutionary multiple sequence alignments (MSAs). However, the computational efficiency and undesirable prediction accuracy of antibodies, especially on the complementarity-determining regions (CDRs) of antibodies limit their applications in the industrially high-throughput drug design. To learn an informative representation of antibodies, we employed a deep antibody language model (ALM) on curated sequences from the observed antibody space database via a transformer model. We also developed a novel model named xTrimoABFold to predict antibody structure from antibody sequence based on the pretrained ALM as well as efficient evoformers and structural modules. The model was trained end-to-end on the antibody structures in PDB by minimizing the ensemble loss of domain-specific focal loss on CDR and the frame-aligned point loss. xTrimoABFold outperforms AlphaFold2 and other protein language model based SOTAs, e.g., OmegaFold, HelixFold-Single, and IgFold with a large significant margin (30+\% improvement on RMSD) while performing 151 times faster than AlphaFold2. To the best of our knowledge, xTrimoABFold achieved state-of-the-art antibody structure prediction. Its improvement in both accuracy and efficiency makes it a valuable tool for de novo antibody design and could make further improvements in immuno-theory.
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尽管近年来,在无单眼制造商的人类运动捕获上取得了重大进展,但最先进的方法仍然很难在遮挡场景中获得令人满意的结果。有两个主要原因:一个是遮挡的运动捕获本质上是模棱两可的,因为各种3D姿势可以映射到相同的2D观测值,这总是导致不可靠的估计。另一个是没有足够的封闭人类数据可用于训练健壮的模型。为了解决这些障碍,我们的钥匙界是使用非封闭式人类数据来学习以自我监督策略的封闭人类的联合时空运动。为了进一步减少合成数据和实际遮挡数据之间的差距,我们构建了第一个3D遮挡运动数据集〜(Ocmotion),可用于训练和测试。我们在2D地图中编码运动,并在非封闭数据上合成遮挡,以进行自我监督训练。然后,设计空间层层以学习联合级别的相关性。博学的先前降低了闭塞的歧义,并且对各种遮挡类型具有坚固态度,然后采用这些类型来帮助封闭的人类运动捕获。实验结果表明,我们的方法可以从具有良好概括能力和运行时效率的遮挡视频中产生准确且相干的人类动作。数据集和代码可在\ url {https://github.com/boycehbz/chomp}上公开获得。
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面部解析将像素语义标签分配为计算机的面部表示,这是许多高级面部技术的基本部分。与2D面对解析相比,3D面对解析具有更大的潜力,可以实现更好的性能和进一步的应用,但是由于3D网格数据计算,它仍然具有挑战性。最近的作品引入了3D表面分割的不同方法,而性能仍然有限。在本文中,我们提出了一种基于“ 3D-2D-3D”策略来完成3D面对解析的方法。包含空间和纹理信息的拓扑磁盘状的2D面图像通过面部参数化算法从采样的3D面数据转换,并提出了一个称为CPFNET的特定2D网络,以实现具有多种参数化脸部数据的语义分割。比例技术和功能聚合。然后,2D语义结果将成反比3D面数据,最终实现了3D面对解析。实验结果表明,CPFNET和“ 3D-2D-3D”策略都完成了高质量的3D面对解析和跑赢大于最新的2D网络以及定性和定量比较的3D方法。
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End-to-end autonomous driving provides a feasible way to automatically maximize overall driving system performance by directly mapping the raw pixels from a front-facing camera to control signals. Recent advanced methods construct a latent world model to map the high dimensional observations into compact latent space. However, the latent states embedded by the world model proposed in previous works may contain a large amount of task-irrelevant information, resulting in low sampling efficiency and poor robustness to input perturbations. Meanwhile, the training data distribution is usually unbalanced, and the learned policy is hard to cope with the corner cases during the driving process. To solve the above challenges, we present a semantic masked recurrent world model (SEM2), which introduces a latent filter to extract key task-relevant features and reconstruct a semantic mask via the filtered features, and is trained with a multi-source data sampler, which aggregates common data and multiple corner case data in a single batch, to balance the data distribution. Extensive experiments on CARLA show that our method outperforms the state-of-the-art approaches in terms of sample efficiency and robustness to input permutations.
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交叉点是自主行驶中最复杂和事故的城市场景之一,其中制造安全和计算有效的决策是非微不足道的。目前的研究主要关注简化的交通状况,同时忽略了混合交通流量的存在,即车辆,骑自行车者和行人。对于城市道路而言,不同的参与者导致了一个非常动态和复杂的互动,从而冒着学习智能政策的困难。本文在集成决策和控制框架中开发动态置换状态表示,以处理与混合业务流的信号化交集。特别地,该表示引入了编码功能和总和运算符,以构建来自环境观察的驱动状态,能够处理不同类型和变体的交通参与者。构建了受约束的最佳控制问题,其中目标涉及跟踪性能,并且不同参与者和信号灯的约束分别设计以确保安全性。我们通过离线优化编码函数,值函数和策略函数来解决这个问题,其中编码函数给出合理的状态表示,然后用作策略和值函数的输入。禁止策略培训旨在重用从驾驶环境中的观察,并且使用时间通过时间来利用策略函数和编码功能联合。验证结果表明,动态置换状态表示可以增强IDC的驱动性能,包括具有大边距的舒适性,决策合规性和安全性。训练有素的驾驶政策可以实现复杂交叉口的高效和平滑通过,同时保证驾驶智能和安全性。
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In this paper, we propose a robust 3D detector, named Cross Modal Transformer (CMT), for end-to-end 3D multi-modal detection. Without explicit view transformation, CMT takes the image and point clouds tokens as inputs and directly outputs accurate 3D bounding boxes. The spatial alignment of multi-modal tokens is performed implicitly, by encoding the 3D points into multi-modal features. The core design of CMT is quite simple while its performance is impressive. CMT obtains 73.0% NDS on nuScenes benchmark. Moreover, CMT has a strong robustness even if the LiDAR is missing. Code will be released at https://github.com/junjie18/CMT.
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Knowledge graphs (KG) have served as the key component of various natural language processing applications. Commonsense knowledge graphs (CKG) are a special type of KG, where entities and relations are composed of free-form text. However, previous works in KG completion and CKG completion suffer from long-tail relations and newly-added relations which do not have many know triples for training. In light of this, few-shot KG completion (FKGC), which requires the strengths of graph representation learning and few-shot learning, has been proposed to challenge the problem of limited annotated data. In this paper, we comprehensively survey previous attempts on such tasks in the form of a series of methods and applications. Specifically, we first introduce FKGC challenges, commonly used KGs, and CKGs. Then we systematically categorize and summarize existing works in terms of the type of KGs and the methods. Finally, we present applications of FKGC models on prediction tasks in different areas and share our thoughts on future research directions of FKGC.
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Few Shot Instance Segmentation (FSIS) requires models to detect and segment novel classes with limited several support examples. In this work, we explore a simple yet unified solution for FSIS as well as its incremental variants, and introduce a new framework named Reference Twice (RefT) to fully explore the relationship between support/query features based on a Transformer-like framework. Our key insights are two folds: Firstly, with the aid of support masks, we can generate dynamic class centers more appropriately to re-weight query features. Secondly, we find that support object queries have already encoded key factors after base training. In this way, the query features can be enhanced twice from two aspects, i.e., feature-level and instance-level. In particular, we firstly design a mask-based dynamic weighting module to enhance support features and then propose to link object queries for better calibration via cross-attention. After the above steps, the novel classes can be improved significantly over our strong baseline. Additionally, our new framework can be easily extended to incremental FSIS with minor modification. When benchmarking results on the COCO dataset for FSIS, gFSIS, and iFSIS settings, our method achieves a competitive performance compared to existing approaches across different shots, e.g., we boost nAP by noticeable +8.2/+9.4 over the current state-of-the-art FSIS method for 10/30-shot. We further demonstrate the superiority of our approach on Few Shot Object Detection. Code and model will be available.
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Graph Neural Networks (GNNs) have shown satisfying performance on various graph learning tasks. To achieve better fitting capability, most GNNs are with a large number of parameters, which makes these GNNs computationally expensive. Therefore, it is difficult to deploy them onto edge devices with scarce computational resources, e.g., mobile phones and wearable smart devices. Knowledge Distillation (KD) is a common solution to compress GNNs, where a light-weighted model (i.e., the student model) is encouraged to mimic the behavior of a computationally expensive GNN (i.e., the teacher GNN model). Nevertheless, most existing GNN-based KD methods lack fairness consideration. As a consequence, the student model usually inherits and even exaggerates the bias from the teacher GNN. To handle such a problem, we take initial steps towards fair knowledge distillation for GNNs. Specifically, we first formulate a novel problem of fair knowledge distillation for GNN-based teacher-student frameworks. Then we propose a principled framework named RELIANT to mitigate the bias exhibited by the student model. Notably, the design of RELIANT is decoupled from any specific teacher and student model structures, and thus can be easily adapted to various GNN-based KD frameworks. We perform extensive experiments on multiple real-world datasets, which corroborates that RELIANT achieves less biased GNN knowledge distillation while maintaining high prediction utility.
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