Miracle-dz/UniFAR-FTUs huggingface dataset:
Online Aggregation based Approximate Query Processing: A Literature Survey

In the current world, OLAP (Online Analytical Processing) is used intensively by modern organizations to perform ad hoc analysis of data, providing insight for better decision making. Thus, the performance for OLAP is crucial; however, it is costly to support OLAP for a large data-set. An approximate query process (AQP) was proposed to efficiently compute approximate values as close as to the exact answer. Existing AQP techniques can be categorized into two parts, online aggregation, and offline synopsis generation, each having its limitations and challenges. Online aggregation-based AQP progressively generates approximate results with some error estimates (i.e., confidence interval) until the processing of all data is done. In Offline synopsis generation-based AQP, synopses are generated offline using a-priori knowledge such as query workload or data statistics. Later, OLAP queries are answered using these synopses. This paper focuses on surveying only the online aggregation-based AQP. For this purpose, firstly, we discuss the research challenges in online aggregation-based AQP and summarize existing approaches to address these challenges. In addition, we also discuss the advantages and limitations of existing online aggregation mechanisms. Lastly, we discuss some research challenges and opportunities for further advancing online aggregation research. Our goal is for people to understand the current progress in the online aggregation-based AQP area and find new insights into it.
Latent Aspect Detection from Online Unsolicited Customer Reviews

Within the context of review analytics, aspects are the features of products and services at which customers target their opinions and sentiments. Aspect detection helps product owners and service providers to identify shortcomings and prioritize customers’ needs, and hence, maintain revenues and mitigate customer churn. Existing methods focus on de-tecting the surface form of an aspect by training supervised learning methods that fall short when aspects are latent in reviews. In this pa-per, we propose an unsupervised method to extract latent occurrences of aspects. Specif-ically, we assume that a customer undergoes a two-stage hypothetical generative process when writing a review: (1) deciding on an aspect amongst the set of aspects available for the product or service, and (2) writing the opinion words that are more interrelated to the chosen aspect from the set of all words available in a language. We employ latent Dirichlet allocation to learn the latent aspects distributions for generating the reviews. Experimental results on benchmark datasets show that our proposed method is able to improve the state of the art when the aspects are latent with no surface form in reviews.
Recommending Code Improvements Based on Stack Overflow Answer Edits

Background: Sub-optimal code is prevalent in software systems. Developers may write low-quality code due to many reasons, such as lack of technical knowledge, lack of experience, time pressure, management decisions, and even unhappiness. Once sub-optimal code is unknowingly (or knowingly) integrated into the codebase of software systems, its accumulation may lead to large maintenance costs and technical debt. Stack Overflow is a popular website for programmers to ask questions and share their code snippets. The crowdsourced and collaborative nature of Stack Overflow has created a large source of programming knowledge that can be leveraged to assist developers in their day-to-day activities. Objective: In this paper, we present an exploratory study to evaluate the usefulness of recommending code improvements based on Stack Overflow answers’ edits. Method: We propose Matcha, a code recommendation tool that leverages Stack Overflow code snippets with version history and code clone search techniques to identify sub-optimal code in software projects and suggest their optimised version. By using SOTorrent and GitHub datasets, we will quali-quantitatively investigate the usefulness of recommendations given by Matcha to developers using manual categorisation of the recommendations and acceptance of pull-requests to open-source projects.
CAMERO: Consistency Regularized Ensemble of Perturbed Language Models with Weight Sharing

Model ensemble is a popular approach to produce a low-variance and well-generalized model. However, it induces large memory and inference costs, which is often not affordable for real-world deployment. Existing work has resorted to sharing weights among models. However, when increasing the proportion of the shared weights, the resulting models tend to be similar, and the benefits of using model ensemble diminish. To retain ensemble benefits while maintaining a low memory cost, we propose a consistency-regularized ensemble learning approach based on perturbed models, named CAMERO. Specifically, we share the weights of bottom layers across all models and apply different perturbations to the hidden representations for different models, which can effectively promote the model diversity. Meanwhile, we apply a prediction consistency regularizer across the perturbed models to control the variance due to the model diversity. Our experiments using large language models demonstrate that CAMERO significantly improves the generalization performance of the ensemble model. Specifically, CAMERO outperforms the standard ensemble of 8 BERT-base models on the GLUE benchmark by 0.7 with a significantly smaller model size (114.2M vs. 880.6M).
A Study of Causal Confusion in Preference-Based Reward Learning

—Learning robot policies via preference-based re- ward learning is an increasingly popular method for customiz-ing robot behavior. However, in recent years, there has been a growing body of anecdotal evidence that learning reward functions from preferences is prone to spurious correlations and reward gaming or hacking behaviors. While there is much anecdotal, empirical, and theoretical analysis of causal confusion and reward gaming behaviors both in reinforcement learning and imitation learning approaches that directly map from states to actions, we provide the ﬁrst systematic study of causal confusion in the context of learning reward functions from preferences. To facilitate this study, we identify a set of three preference learning benchmark domains where we observe causal confusion when learning from ofﬂine datasets of pairwise trajectory preferences: a simple reacher domain, an assistive feeding domain, and an itch-scratching domain. To gain insight into this observed causal confusion, we present a sensitivity analysis that explores the effect of different factors— including the type of training data, reward model capacity, and feature dimensionality—on the robustness of rewards learned from preferences. We ﬁnd evidence that learning rewards from pairwise trajectory preferences is highly sensitive and non-robust to spurious features and increasing model capacity, but not as sensitive to the type of training data. Videos, code, and supplemental results are available at https://sites. google.com/view/causal-reward-confusion . position, arm angles, target coordinates, and angular velocities, for a total raw observation dimensionality of 11. The Itch Scratching environment’s raw features consist of tool and target position, robot and human joint angles, and the force applied by the tool, for a total dimensionality of 30. For each environment, raw features are progressively concatenated onto the entire set of privileged features.
Accelerated Policy Learning with Parallel Differentiable Simulation

Deep reinforcement learning can generate complex control policies, but requires large amounts of training data to work effectively. Recent work has attempted to address this issue by leveraging differentiable simulators. However, inherent problems such as local minima and exploding/vanishing numerical gradients prevent these methods from being generally applied to control tasks with complex contact-rich dynamics, such as humanoid locomotion in classical RL benchmarks. In this work we present a high-performance differentiable simulator and a new policy learning algorithm (SHAC) that can effectively leverage simulation gradients, even in the presence of non-smoothness. Our learning algorithm alleviates problems with local minima through a smooth critic function, avoids vanishing/exploding gradients through a truncated learning window, and allows many physical environments to be run in parallel. We evaluate our method on classical RL control tasks, and show substantial improvements in sample efficiency and wall-clock time over state-of-the-art RL and differentiable simulation-based algorithms. In addition, we demonstrate the scalability of our method by applying it to the challenging high-dimensional problem of muscle-actuated locomotion with a large action space, achieving a greater than 17x reduction in training time over the best-performing established RL algorithm.
Character-focused Video Thumbnail Retrieval

We explore retrieving character-focused video frames as candidates for being video thumbnails. To evaluate each frame of the video based on the character(s) present in it, characters (faces) are evaluated in two aspects: Facial-expression : We train a CNN model to measure whether a face has an acceptable facial expression for being in a video thumbnail. This model is trained to distinguish faces extracted from artworks/thumbnails, from faces extracted from random frames of videos. Prominence and interactions : Character(s) in the thumbnail should be important character(s) in the video, to prevent the algorithm from suggest-ing non-representative frames as candidates. We use face clustering to identify the characters in the video, and form a graph in which the prominence (frequency of appearance) of the character(s), and their interactions (co-occurrence) are captured. We use this graph to infer the relevance of the characters present in each candidate frame. Once every face is scored based on the two criteria above, we infer frame level scores by combining the scores for all the faces within a frame.
Modularity benefits reinforcement learning agents with competing homeostatic drives

The problem of balancing conflicting needs is fundamental to intelligence. Standard reinforcement learning algorithms maximize a scalar reward, which requires combining different objective-specific rewards into a single number. Alternatively, different objectives could also be combined at the level of action value, such that specialist modules responsible for different objectives submit different action suggestions to a decision process, each based on rewards that are independent of one another. In this work, we explore the potential benefits of this alternative strategy. We investigate a biologically relevant multi-objective problem, the continual homeostasis of a set of variables, and compare a monolithic deep Q-network to a modular network with a dedicated Q-learner for each variable. We find that the modular agent: a) requires minimal exogenously determined exploration; b) has improved sample efficiency; and c) is more robust to out-of-domain perturbation.
Human Identity-Preserved Motion Retargeting in Video Synthesis by Feature Disentanglement

Most motion retargeting methods in human action video synthesis decompose the input video to motion (dynamic information) and shape (static information). However, we observe if the dynamic information is directly transferred to another subject, it will result in unnatural synthesised motion. This phenomenon is mainly caused by neglecting subject-dependent information in motion. To solve the problem, we propose a novel motion retargeting method which can combine both subject-independent (common motion content) information from a source video and subject-dependent (individualized identity motion) information from a target video. So it can synthesize videos with a much natural appearance along with identity-preserved motion (Figure 1). In the proposed method two encoders are employed to extract identity and motion content representations respectively. We employ the adaptive instance normalization (AdaIN) layer in the generator and the instance normalization (IN) layer in the motion content encoder to synthesize the new motion. Besides, we also collected a dataset, named 𝐶ℎ𝑢𝑎𝑛𝑔 101, with 101 subjects in total. Each subject performs identical dancing movement, and so it is convenient for feature disentanglement among motion and identity of each subject. Furthermore, an efficient quantitative metric for identify information is designed by gait recognition. The experiments show the proposed method can synthesize videos more naturally when the subject’s identity is preserved.
Environment Imitation: Data-Driven Environment Model Generation Using Imitation Learning for Efficient CPS Goal Verification

Cyber-Physical Systems (CPS) continuously interact with their physical environments through software controllers that observe the environments and determine actions. Engineers can verify to what extent the CPS under analysis can achieve given goals by analyzing its Field Operational Test (FOT) logs. However, it is challenging to repeat many FOTs to obtain statistically signiﬁcant results due to its cost and risk in practice. To address this challenge, simulation-based veriﬁcation can be a good alternative for eﬃcient CPS goal veriﬁcation, but it requires an accurate virtual environment model that can replace the real environment that interacts with the CPS in a closed loop. This paper proposes a novel data-driven approach that automatically generates the virtual environment model from a small amount of FOT logs. We formally deﬁne the environment model generation problem and solve it using Imitation Learning (IL) algorithms. In addition, we propose three speciﬁc use cases of our approach in the evolutionary CPS development. To validate our approach, we conduct a case study using a simpliﬁed autonomous vehicle with a lane-keeping system. The case study results show that our approach can generate accurate virtual environment models for CPS goal veriﬁcation at a low cost through simulations.
Improving Top-K Decoding for Non-Autoregressive Semantic Parsing via Intent Conditioning

Semantic parsing (SP) is a core component of modern virtual assistants like Google Assistant and Amazon Alexa. While sequence-to-sequence based auto-regressive (AR) approaches are common for conversational SP, recent studies employ non-autoregressive (NAR) decoders and reduce inference latency while maintaining competitive parsing quality. However, a major drawback of NAR decoders is the difficulty of generating top-k (i.e., k-best) outputs with approaches such as beam search. To address this challenge, we propose a novel NAR semantic parser that introduces intent conditioning on the decoder. Inspired by the traditional intent and slot tagging parsers, we decouple the top-level intent prediction from the rest of a parse. As the top-level intent largely governs the syntax and semantics of a parse, the intent conditioning allows the model to better control beam search and improves the quality and diversity of top-k outputs. We introduce a hybrid teacher-forcing approach to avoid training and inference mismatch. We evaluate the proposed NAR on conversational SP datasets, TOP & TOPv2. Like the existing NAR models, we maintain the O(1) decoding time complexity while generating more diverse outputs and improving top-3 exact match (EM) by 2.4 points. In comparison with AR models, our model speeds up beam search inference by 6.7 times on CPU with competitive top-k EM.
Wassmap: Wasserstein Isometric Mapping for Image Manifold Learning

In this paper, we propose Wasserstein Isometric Mapping (Wassmap), a nonlinear dimensionality reduction technique that provides solutions to some drawbacks in existing global nonlinear dimensionality reduction algorithms in imaging applications. Wassmap represents images via probability measures in Wasserstein space, then uses pairwise Wasserstein distances between the associated measures to produce a low-dimensional, approximately isometric embedding. We show that the algorithm is able to exactly recover parameters of some image manifolds including those generated by translations or dilations of a fixed generating measure. Additionally, we show that a discrete version of the algorithm retrieves parameters from manifolds generated from discrete measures by providing a theoretical bridge to transfer recovery results from functional data to discrete data. Testing of the proposed algorithms on various image data manifolds show that Wassmap yields good embeddings compared with other global and local techniques.
Learning to Generalize to More: Continuous Semantic Augmentation for Neural Machine Translation

The principal task in supervised neural machine translation (NMT) is to learn to generate target sentences conditioned on the source inputs from a set of parallel sentence pairs, and thus produce a model capable of generalizing to unseen instances. However, it is commonly observed that the generalization performance of the model is highly influenced by the amount of parallel data used in training. Although data augmentation is widely used to enrich the training data, conventional methods with discrete manipulations fail to generate diverse and faithful training samples. In this paper, we present a novel data augmentation paradigm termed Continuous Semantic Augmentation (CsaNMT), which augments each training instance with an adjacency semantic region that could cover adequate variants of literal expression under the same meaning. We conduct extensive experiments on both rich-resource and low-resource settings involving various language pairs, including WMT14 English\rightarrow{German,French}, NIST Chinese\rightarrowEnglish and multiple low-resource IWSLT translation tasks. The provided empirical evidences show that CsaNMT sets a new level of performance among existing augmentation techniques, improving on the state-of-the-art by a large margin. The core codes are contained in Appendix E.
Time Series of Non-Additive Metrics: Identification and Interpretation of Contributing Factors of Variance by Linear Decomposition

The research paper addresses linear decomposition of time series of non-additive metrics that allows for the identification and interpretation of contributing factors (input features) of variance. Non-additive metrics, such as ratios, are widely used in a variety of domains. It commonly requires preceding aggregations of underlying variables that are used to calculate the metric of interest. The latest poses a dimensionality challenge when the input features and underlying variables are formed as two-dimensional arrays along elements, such as account or customer identifications, and time points. It rules out direct modeling of the time series of a non-additive metric as a function of input features. The article discusses a five-step approach: (1) segmentations of input features and the underlying variables of the metric that are supported by unsupervised autoencoders, (2) univariate or joint fittings of the metric by the aggregated input features on the segmented domains, (3) transformations of pre-screened input features according to the fitted models, (4) aggregation of the transformed features as time series, and (5) modelling of the metric time series as a sum of constrained linear effects of the aggregated features. Alternatively, approximation by numerical differentiation has been considered to linearize the metric. It allows for element level univariate or joint modeling of step (2). The process of these analytical steps allows for a backward-looking explanatory decomposition of the metric as a sum of time series of the survived input features. The paper includes a synthetic example that studies loss-to-balance monthly rates of a hypothetical retail credit portfolio. To validate that no latent factors other than the survived input features have significant impacts on the metric, Statistical Process Control has been introduced for the residual time series.
Learning fixed-complexity polyhedral Lyapunov functions from counterexamples

We study the problem of synthesizing polyhedral Lyapunov functions for hybrid linear systems. Such functions are defined as convex piecewise linear functions, with a finite number of pieces. We first prove that deciding whether there exists an m-piece polyhedral Lyapunov function for a given hybrid linear system is NP-hard. We then present a counterexample-guided algorithm for solving this problem. The algorithm alternates between choosing a candidate polyhedral function based on a finite set of counterexamples and verifying whether the candidate satisfies the Lyapunov conditions. If the verification fails, we find a new counterexample that is added to our set. We prove that if the algorithm terminates, it discovers a valid Lyapunov function or concludes that no such Lyapunov function exists. However, our initial algorithm can be nonterminating. We modify our algorithm to provide a terminating version based on the so-called cutting-plane argument from nonsmooth optimization. We demonstrate our algorithm on numerical examples.
A deep learning algorithm for reducing false positives in screening mammography

Screening mammography improves breast cancer outcomes by enabling early detection and treatment. However, false positive callbacks for additional imaging from screening exams cause unnecessary procedures, patient anxiety, and financial burden. This work demonstrates an AI algorithm that reduces false positives by identifying mammograms not suspicious for breast cancer. We trained the algorithm to determine the absence of cancer using 123,248 2D digital mammograms (6,161 cancers) and performed a retrospective study on 14,831 screening exams (1,026 cancers) from 15 US and 3 UK sites. Retrospective evaluation of the algorithm on the largest of the US sites (11,592 mammograms, 101 cancers) a) left the cancer detection rate unaffected (p=0.02, non-inferiority margin 0.25 cancers per 1000 exams), b) reduced callbacks for diagnostic exams by 31.1% compared to standard clinical readings, c) reduced benign needle biopsies by 7.4%, and d) reduced screening exams requiring radiologist interpretation by 41.6% in the simulated clinical workflow. This work lays the foundation for semi-autonomous breast cancer screening systems that could benefit patients and healthcare systems by reducing false positives, unnecessary procedures, patient anxiety, and expenses.