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Graphemic Normalization of the Perso-Arabic Script

arXiv.org Artificial Intelligence

Since its original appearance in 1991, the Perso-Arabic script representation in Unicode has grown from 169 to over 440 atomic isolated characters spread over several code pages representing standard letters, various diacritics and punctuation for the original Arabic and numerous other regional orthographic traditions. This paper documents the challenges that Perso-Arabic presents beyond the best-documented languages, such as Arabic and Persian, building on earlier work by the expert community. We particularly focus on the situation in natural language processing (NLP), which is affected by multiple, often neglected, issues such as the use of visually ambiguous yet canonically nonequivalent letters and the mixing of letters from different orthographies. Among the contributing conflating factors are the lack of input methods, the instability of modern orthographies, insufficient literacy, and loss or lack of orthographic tradition. We evaluate the effects of script normalization on eight languages from diverse language families in the Perso-Arabic script diaspora on machine translation and statistical language modeling tasks. Our results indicate statistically significant improvements in performance in most conditions for all the languages considered when normalization is applied. We argue that better understanding and representation of Perso-Arabic script variation within regional orthographic traditions, where those are present, is crucial for further progress of modern computational NLP techniques especially for languages with a paucity of resources.


Mapping Extended Landmarks for Radar SLAM

arXiv.org Artificial Intelligence

In the early years, algorithms Simultaneous localization and mapping (SLAM) using automotive developed for landmark-based SLAM operated under the assumption radar sensors can provide enhanced sensing capabilities that each landmark can generate at most one measurement for autonomous systems. In SLAM applications, with per scan (point landmark), and therefore mainly focused a greater requirement for the environment map, information on estimating the location of landmarks. However, with on the extent of landmarks is vital for precise navigation and the advent of high resolution automotive radar sensors, landmarks path planning. Although object extent estimation has been may occupy multiple radar resolution cells and hence successfully applied in target tracking, its adaption to SLAM generating more than one radar detection per scan, i.e. an remains unaddressed due to the additional uncertainty of the extended landmark. By exploiting information such as the location sensor platform, bias in the odometer reading, as well as the of each radar detection, as well as their spacial spread, measurement non-linearity. In this paper, we propose to incorporate we can also estimate the size and orientation of a landmark, the Bayesian random matrix approach to estimate in addition to its centroid location.


PAGE: Prototype-Based Model-Level Explanations for Graph Neural Networks

arXiv.org Artificial Intelligence

Aside from graph neural networks (GNNs) catching significant attention as a powerful framework revolutionizing graph representation learning, there has been an increasing demand for explaining GNN models. Although various explanation methods for GNNs have been developed, most studies have focused on instance-level explanations, which produce explanations tailored to a given graph instance. In our study, we propose Prototype-bAsed GNN-Explainer (PAGE), a novel model-level GNN explanation method that explains what the underlying GNN model has learned for graph classification by discovering human-interpretable prototype graphs. Our method produces explanations for a given class, thus being capable of offering more concise and comprehensive explanations than those of instance-level explanations. First, PAGE selects embeddings of class-discriminative input graphs on the graph-level embedding space after clustering them. Then, PAGE discovers a common subgraph pattern by iteratively searching for high matching node tuples using node-level embeddings via a prototype scoring function, thereby yielding a prototype graph as our explanation. Using five graph classification datasets, we demonstrate that PAGE qualitatively and quantitatively outperforms the state-of-the-art model-level explanation method. We also carry out experimental studies systematically by showing the relationship between PAGE and instance-level explanation methods, the robustness of PAGE to input data scarce environments, and the computational efficiency of the proposed prototype scoring function in PAGE.


50 Ways to Bake a Cookie: Mapping the Landscape of Procedural Texts

arXiv.org Artificial Intelligence

However, as content However, a single task might have thousands of corresponding is created independently, a single task could have thousands of procedural texts. This is both due to variations (for example, different corresponding procedural texts. This makes it difficult for users to recipes for the same dish) and due to the distributed nature view the bigger picture and understand the multiple ways the task of the web, where content is created independently by people who could be accomplished. In this work we propose an unsupervised do not communicate. Thus, looking at one (or a few) procedural learning approach for summarizing multiple procedural texts texts only gives the reader a limited view of the possibilities. Consequently, into an intuitive graph representation, allowing users to easily explore when people try to determine the best choice for them commonalities and differences. We demonstrate our approach given preferences (e.g., taste) and constraints (budget, time, items on recipes, a prominent example of procedural texts. User studies they do or do not have), they often resort to extensive browsing show that our representation is intuitive and coherent and that and comparisons between different texts to get the bigger picture.


Edgeless-GNN: Unsupervised Representation Learning for Edgeless Nodes

arXiv.org Artificial Intelligence

We study the problem of embedding edgeless nodes such as users who newly enter the underlying network, while using graph neural networks (GNNs) widely studied for effective representation learning of graphs. Our study is motivated by the fact that GNNs cannot be straightforwardly adopted for our problem since message passing to such edgeless nodes having no connections is impossible. To tackle this challenge, we propose Edgeless-GNN, a novel inductive framework that enables GNNs to generate node embeddings even for edgeless nodes through unsupervised learning. Specifically, we start by constructing a proxy graph based on the similarity of node attributes as the GNN's computation graph defined by the underlying network. The known network structure is used to train model parameters, whereas a topology-aware loss function is established in such a way that our model judiciously learns the network structure by encoding positive, negative, and second-order relations between nodes. For the edgeless nodes, we inductively infer embeddings by expanding the computation graph. By evaluating the performance of various downstream machine learning tasks, we empirically demonstrate that Edgeless-GNN exhibits (a) superiority over state-of-the-art inductive network embedding methods for edgeless nodes, (b) effectiveness of our topology-aware loss function, (c) robustness to incomplete node attributes, and (d) a linear scaling with the graph size.


VertiBayes: Learning Bayesian network parameters from vertically partitioned data with missing values

arXiv.org Artificial Intelligence

Federated learning makes it possible to train a machine learning model on decentralized data. Bayesian networks are probabilistic graphical models that have been widely used in artificial intelligence applications. Their popularity stems from the fact they can be built by combining existing expert knowledge with data and are highly interpretable, which makes them useful for decision support, e.g. in healthcare. While some research has been published on the federated learning of Bayesian networks, publications on Bayesian networks in a vertically partitioned or heterogeneous data setting (where different variables are located in different datasets) are limited, and suffer from important omissions, such as the handling of missing data. In this article, we propose a novel method called VertiBayes to train Bayesian networks (structure and parameters) on vertically partitioned data, which can handle missing values as well as an arbitrary number of parties. For structure learning we adapted the widely used K2 algorithm with a privacy-preserving scalar product protocol. For parameter learning, we use a two-step approach: first, we learn an intermediate model using maximum likelihood by treating missing values as a special value and then we train a model on synthetic data generated by the intermediate model using the EM algorithm. The privacy guarantees of our approach are equivalent to the ones provided by the privacy preserving scalar product protocol used. We experimentally show our approach produces models comparable to those learnt using traditional algorithms and we estimate the increase in complexity in terms of samples, network size, and complexity. Finally, we propose two alternative approaches to estimate the performance of the model using vertically partitioned data and we show in experiments that they lead to reasonably accurate estimates.


Effective Cross-Task Transfer Learning for Explainable Natural Language Inference with T5

arXiv.org Artificial Intelligence

We compare sequential fine-tuning with a model for multi-task learning in the context where we are interested in boosting performance on two tasks, one of which depends on the other. We test these models on the FigLang2022 shared task which requires participants to predict language inference labels on figurative language along with corresponding textual explanations of the inference predictions. Our results show that while sequential multi-task learning can be tuned to be good at the first of two target tasks, it performs less well on the second and additionally struggles with overfitting. Our findings show that simple sequential fine-tuning of text-to-text models is an extraordinarily powerful method for cross-task knowledge transfer while simultaneously predicting multiple interdependent targets. So much so, that our best model achieved the (tied) highest score on the task.


Real-time Mapping of Physical Scene Properties with an Autonomous Robot Experimenter

arXiv.org Artificial Intelligence

In this work, we present a real-world robot that learns about its environment by autonomous exploration and experimentation. The robot incrementally discovers physical scene properties by performing targeted physical interactions with the scene, measuring their effects and feeding the results into a jointly-optimised neural-field MLP. With only a handful of these autonomous robotic experiments, a task-driven internal representation of the scene is built from scratch, without any pre-training or external guidance. We build upon the observation that the joint internal representation of shape and appearance learned by implicit scene representation models, and the smoothness and compactness priors present in these models, allow for ultra-efficient, scene-wide propagation of user-provided labels [2]. We remove the human from the loop entirely, presenting the first fully-autonomous, 3D scene understanding robot that combines active exploration and physical experimentation with a unified neural-field representation as its underlying computational model. The robot explores a scene with an RGB-D camera and simultaneously builds a map of semantic entropy, representing confidence in its current predictions. Considering this entropy, as well as kinematic feasibility and collision avoidance, the robot selects the optimal point of interaction and proceeds to take a physical measurement used for optimising the semantic head of the underlying MLP.


Formulating Few-shot Fine-tuning Towards Language Model Pre-training: A Pilot Study on Named Entity Recognition

arXiv.org Artificial Intelligence

Fine-tuning pre-trained language models has recently become a common practice in building NLP models for various tasks, especially few-shot tasks. We argue that under the few-shot setting, formulating fine-tuning closer to the pre-training objectives shall be able to unleash more benefits from the pre-trained language models. In this work, we take few-shot named entity recognition (NER) for a pilot study, where existing fine-tuning strategies are much different from pre-training. We propose a novel few-shot fine-tuning framework for NER, FFF-NER. Specifically, we introduce three new types of tokens, "is-entity", "which-type" and bracket, so we can formulate the NER fine-tuning as (masked) token prediction or generation, depending on the choice of pre-trained language models. In our experiments, we apply FFF-NER to fine-tune both BERT and BART for few-shot NER on several benchmark datasets and observe significant improvements over existing fine-tuning strategies, including sequence labeling, prototype meta-learning, and prompt-based approaches. We further perform a series of ablation studies, showing few-shot NER performance is strongly correlated with the similarity between fine-tuning and pre-training.


Reinforced Question Rewriting for Conversational Question Answering

arXiv.org Artificial Intelligence

Conversational Question Answering (CQA) aims to answer questions contained within dialogues, which are not easily interpretable without context. Developing a model to rewrite conversational questions into self-contained ones is an emerging solution in industry settings as it allows using existing single-turn QA systems to avoid training a CQA model from scratch. Previous work trains rewriting models using human rewrites as supervision. However, such objectives are disconnected with QA models and therefore more human-like rewrites do not guarantee better QA performance. In this paper we propose using QA feedback to supervise the rewriting model with reinforcement learning. Experiments show that our approach can effectively improve QA performance over baselines for both extractive and retrieval QA. Furthermore, human evaluation shows that our method can generate more accurate and detailed rewrites when compared to human annotations.