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LocallyDifferentiallyPrivate (Contextual)Bandits Learning

Neural Information Processing Systems

Further, we extend our(ε,δ)-LDP algorithm toGeneralized Linear Bandits,which enjoysa sub-linear regret O(T3/4/ε) and is conjectured to be nearly optimal. Note that given the existingΩ(T) lower bound for DP contextual linear bandits [35], our result shows afundamental difference between LDP and DP contextual bandits learning.



Appendices 619 A Additional Experiments 620

Neural Information Processing Systems

Table 6: Results of selected models on Task 1 (Grouping) using contextual embeddings. In this section, we provide additional t-SNE projections of embeddings from various methods used. Figure 7: Solved wall for Task 1 (Grouping) using GloV e. Left: ( " Suspension" is " a term used in musical harmony " in this context. Grief " in the embedding space, which matches the " Good ___! " connection. Figure 8: Solved wall for Task 1 (Grouping) using FastText (Crawl). Left: contextual embedding solved 3/4 groups. Here the clue " Rambrandt" is placed near other Dutch painters. Right: static embedding solved 0/4 groups. The following section provides answers to questions listed in datasheets for datasets. For what purpose was the dataset created? Was there a specific task in mind? Who created this dataset (e.g., which team, research group) and on behalf of which entity (e.g., The dataset has been collectively curated by the authors of this paper. What support was needed to make this dataset?



Group Contextual Encoding for 3D Point Clouds

Neural Information Processing Systems

Global context is crucial for 3D point cloud scene understanding tasks. In this work, we extended the contextual encoding layer that was originally designed for 2D tasks to 3D Point Cloud scenarios. The encoding layer learns a set of code words in the feature space of the 3D point cloud to characterize the global semantic context, and then based on these code words, the method learns a global contextual descriptor to reweight the featuremaps accordingly. Moreover, compared to 2D scenarios, data sparsity becomes a major issue in 3D point cloud scenarios, and the performance of contextual encoding quickly saturates when the number of code words increases. To mitigate this problem, we further proposed a group contextual encoding method, which divides the channel into groups and then performs encoding on group-divided feature vectors.


Locally Differentially Private (Contextual) Bandits Learning

Neural Information Processing Systems

We study locally differentially private (LDP) bandits learning in this paper. First, we propose simple black-box reduction frameworks that can solve a large family of context-free bandits learning problems with LDP guarantee. Based on our frameworks, we can improve previous best results for private bandits learning with one-point feedback, such as private Bandits Convex Optimization etc, and obtain the first results for Bandits Convex Optimization (BCO) with multi-point feedback under LDP. LDP guarantee and black-box nature make our frameworks more attractive in real applications compared with previous specifically designed and relatively weaker differentially private (DP) algorithms. Further, we also extend our algorithm to Generalized Linear Bandits with regret bound $\tilde{\mc{O}}(T^{3/4}/\varepsilon)$ under $(\varepsilon, \delta)$-LDP and it is conjectured to be optimal. Note given existing $\Omega(T)$ lower bound for DP contextual linear bandits (Shariff & Sheffet, NeurIPS 2018), our result shows a fundamental difference between LDP and DP for contextual bandits.


Statistical Inference with M-Estimators on Adaptively Collected Data

Neural Information Processing Systems

Bandit algorithms are increasingly used in real-world sequential decision-making problems. Associated with this is an increased desire to be able to use the resulting datasets to answer scientific questions like: Did one type of ad lead to more purchases? In which contexts is a mobile health intervention effective? However, classical statistical approaches fail to provide valid confidence intervals when used with data collected with bandit algorithms. Alternative methods have recently been developed for simple models (e.g., comparison of means). Yet there is a lack of general methods for conducting statistical inference using more complex models on data collected with (contextual) bandit algorithms; for example, current methods cannot be used for valid inference on parameters in a logistic regression model for a binary reward. In this work, we develop theory justifying the use of M-estimators---which includes estimators based on empirical risk minimization as well as maximum likelihood---on data collected with adaptive algorithms, including (contextual) bandit algorithms. Specifically, we show that M-estimators, modified with particular adaptive weights, can be used to construct asymptotically valid confidence regions for a variety of inferential targets.


Retrieval Augmented Generation based context discovery for ASR

Siskos, Dimitrios, Papadopoulos, Stavros, Parada, Pablo Peso, Zhang, Jisi, Saravanan, Karthikeyan, Drosou, Anastasios

arXiv.org Artificial Intelligence

This work investigates retrieval augmented generation as an efficient strategy for automatic context discovery in context-aware Automatic Speech Recognition (ASR) system, in order to improve transcription accuracy in the presence of rare or out-of-vocabulary terms. However, identifying the right context automatically remains an open challenge. This work proposes an efficient embedding-based retrieval approach for automatic context discovery in ASR. To contextualize its effectiveness, two alternatives based on large language models (LLMs) are also evaluated: (1) large language model (LLM)-based context generation via prompting, and (2) post-recognition transcript correction using LLMs. Experiments on the TED-LIUMv3, Earnings21 and SPGISpeech demonstrate that the proposed approach reduces WER by up to 17% (percentage difference) relative to using no-context, while the oracle context results in a reduction of up to 24.1%.