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 Deep Learning



Details and Ablation Studies for Language Modelling

Neural Information Processing Systems

A.1 Experimental Settings All language models in Table 1 have the same Transformer configuration: a 16-layer model with a hidden size of 128 with 8 heads, and a feed-forward dimension of 2048. We use a dropout [75, 76, 77] rate of 0.1. The batch size is 96 and we train for about 120 epochs with Adam optimiser [78] with an initial learning rate of 0.00025 and 2000 learning rate warm-up steps. All models are trained with a back-propagation span of 256 tokens. During training, these segments are treated independently, except for the + full context cases in Table 1 where the states (both recurrent states and fast weight states) from a segment are used as initialisation for the subsequent segment. The models in + full context cases are also evaluated in the same way by carrying over the context throughout the evaluation text with a batch size of one. For all other cases, the evaluation is done by going through the text with a sliding window of size 256 with a batch size of one. Transformer states are computed for all positions in each window, but only the last position is used to compute perplexity (except in the first segment where all positions are used for evaluation) [2].



SADGA: Structure-Aware Dual Graph Aggregation Network for Text-to-SQL

Neural Information Processing Systems

The Text-to-SQL task, aiming to translate the natural language of the questions into SQL queries, has drawn much attention recently. One of the most challenging problems of Text-to-SQL is how to generalize the trained model to the unseen database schemas, also known as the cross-domain Text-to-SQL task. The key lies in the generalizability of (i) the encoding method to model the question and the database schema and (ii) the question-schema linking method to learn the mapping between words in the question and tables/columns in the database schema. Focusing on the above two key issues, we propose a Structure-Aware Dual Graph Aggregation Network (SADGA) for cross-domain Text-to-SQL. In SADGA, we adopt the graph structure to provide a unified encoding model for both the natural language question and database schema. Based on the proposed unified modeling, we further devise a structure-aware aggregation method to learn the mapping between the question-graph and schema-graph. The structure-aware aggregation method is featured with Global Graph Linking, Local Graph Linking and DualGraph Aggregation Mechanism. We not only study the performance of our proposal empirically but also achieved 3rd place on the challenging Text-to-SQL benchmark Spider at the time of writing.


Supplementary Materials of Random Noise Defense against Query-Based Black-Box Attacks

Neural Information Processing Systems

In this supplementary document, we provide additional materials to supplement our main submission. In Section A, we talk about the societal impacts of our work In Section B, we provide detailed experimental settings as well as further evaluation results on CIFAR-10 and ImageNet. We also provide the comparison with input transformation-based defense methods. In Section D, we give the proofs w.r.t. In Section E, we give the proofs w.r.t. The proofs of Theorem 3 are given in Section F. In Section C, we provide the analysis and evaluation of decision-based attacks. Deep neural networks (DNNs) have been successfully applied in many safety-critical tasks, such as autonomous driving, face recognition and verification, etc. And adversarial samples have posed a serious threat to machine learning systems.


Beyond MLE: Convex Learning for Text Generation

Neural Information Processing Systems

Maximum likelihood estimation (MLE) is a statistical method used to estimate the parameters of a probability distribution that best explain the observed data. In the context of text generation, MLE is often used to train generative language models, which can then be used to generate new text. However, we argue that MLE is not always necessary and optimal, especially for closed-ended text generation tasks like machine translation. In these tasks, the goal of model is to generate the most appropriate response, which does not necessarily require it to estimate the entire data distribution with MLE. To this end, we propose a novel class of training objectives based on convex functions, which enables text generation models to focus on highly probable outputs without having to estimate the entire data distribution. We investigate the theoretical properties of the optimal predicted distribution when applying convex functions to the loss, demonstrating that convex functions can sharpen the optimal distribution, thereby enabling the model to better capture outputs with high probabilities. Experiments on various text generation tasks and models show the effectiveness of our approach. It enables autoregressive models to bridge the gap between greedy and beam search, and facilitates the learning of non-autoregressive models with a maximum improvement of 9+ BLEU points. Moreover, our approach also exhibits significant impact on large language models (LLMs), substantially enhancing their generative capability on various tasks.




The Double-Edged Sword of Implicit Bias: Generalization vs. Robustness in ReLU Networks

Neural Information Processing Systems

In this work, we study the implications of the implicit bias of gradient flow on generalization and adversarial robustness in ReLU networks. We focus on a setting where the data consists of clusters and the correlations between cluster means are small, and show that in two-layer ReLU networks gradient flow is biased towards solutions that generalize well, but are vulnerable to adversarial examples. Our results hold even in cases where the network is highly overparameterized. Despite the potential for harmful overfitting in such settings, we prove that the implicit bias of gradient flow prevents it. However, the implicit bias also leads to non-robust solutions (susceptible to small adversarial ℓ2-perturbations), even though robust networks that fit the data exist.