Goto

Collaborating Authors

 Oceania


Robust Neural Regression via Uncertainty Learning

arXiv.org Machine Learning

Deep neural networks tend to underestimate uncertainty and produce overly confident predictions. Recently proposed solutions, such as MC Dropout and SDENet, require complex training and/or auxiliary out-of-distribution data. We propose a simple solution by extending the time-tested iterative reweighted least square (IRLS) in generalised linear regression. We use two sub-networks to parametrise the prediction and uncertainty estimation, enabling easy handling of complex inputs and nonlinear response. The two sub-networks have shared representations and are trained via two complementary loss functions for the prediction and the uncertainty estimates, with interleaving steps as in a cooperative game. Compared with more complex models such as MC-Dropout or SDE-Net, our proposed network is simpler to implement and more robust (insensitive to varying aleatoric and epistemic uncertainty).


Reward-Free Model-Based Reinforcement Learning with Linear Function Approximation

arXiv.org Machine Learning

We study the model-based reward-free reinforcement learning with linear function approximation for episodic Markov decision processes (MDPs). In this setting, the agent works in two phases. In the exploration phase, the agent interacts with the environment and collects samples without the reward. In the planning phase, the agent is given a specific reward function and uses samples collected from the exploration phase to learn a good policy. We propose a new provably efficient algorithm, called UCRL-RFE under the Linear Mixture MDP assumption, where the transition probability kernel of the MDP can be parameterized by a linear function over certain feature mappings defined on the triplet of state, action, and next state. We show that to obtain an $\epsilon$-optimal policy for arbitrary reward function, UCRL-RFE needs to sample at most $\tilde O(H^5d^2\epsilon^{-2})$ episodes during the exploration phase. Here, $H$ is the length of the episode, $d$ is the dimension of the feature mapping. We also propose a variant of UCRL-RFE using Bernstein-type bonus and show that it needs to sample at most $\tilde O(H^4d(H + d)\epsilon^{-2})$ to achieve an $\epsilon$-optimal policy. By constructing a special class of linear Mixture MDPs, we also prove that for any reward-free algorithm, it needs to sample at least $\tilde \Omega(H^2d\epsilon^{-2})$ episodes to obtain an $\epsilon$-optimal policy. Our upper bound matches the lower bound in terms of the dependence on $\epsilon$ and the dependence on $d$ if $H \ge d$.


Quantifying With Only Positive Training Data

arXiv.org Machine Learning

Quantification is the research field that studies methods for counting the number of data points that belong to each class in an unlabeled sample. Traditionally, researchers in this field assume the availability of labelled observations for all classes to induce a quantification model. However, we often face situations where the number of classes is large or even unknown, or we have reliable data for a single class. When inducing a multi-class quantifier is infeasible, we are often concerned with estimates for a specific class of interest. In this context, we have proposed a novel setting known as One-class Quantification (OCQ). In contrast, Positive and Unlabeled Learning (PUL), another branch of Machine Learning, has offered solutions to OCQ, despite quantification not being the focal point of PUL. This article closes the gap between PUL and OCQ and brings both areas together under a unified view. We compare our method, Passive Aggressive Threshold (PAT), against PUL methods and show that PAT generally is the fastest and most accurate algorithm. PAT induces quantification models that can be reused to quantify different samples of data. We additionally introduce Exhaustive TIcE (ExTIcE), an improved version of the PUL algorithm Tree Induction for c Estimation (TIcE). We show that ExTIcE quantifies more accurately than PAT and the other assessed algorithms in scenarios where several negative observations are identical to the positive ones.


Airbus' solar-powered aircraft Zephyr completes two 18-day flights

Daily Mail - Science & tech

Aerospace firm Airbus has completed two 18-day stratospheric flights of its solar-powered aircraft, called Zephyr, 76,100 feet above the Earth. Zephyr's solar powered test flights in the stratosphere – the second layer of the Earth's atmosphere – set a new world record for altitude this summer, Airbus says. The firm now wants to deploy the'high altitude pseudo-satellite' (HAPS) for surveillance and beaming broadband down to remote areas that don't have internet. Zephyr, an UAV with two small propellers, is powered exclusively by the Sun, thanks to solar panels lining its whole 82-foot wingspan. It's typically hand-launched by four to five ground crew, fast-walking or jogging into a light wind, but it features on-board software for remote navigation.


Synthetic Media: How deepfakes could soon change our world

#artificialintelligence

You may never have heard the term "synthetic media"-- more commonly known as "deepfakes"-- but our military, law enforcement and intelligence agencies certainly have. They are hyper-realistic video and audio recordings that use artificial intelligence and "deep" learning to create "fake" content or "deepfakes." The U.S. government has grown increasingly concerned about their potential to be used to spread disinformation and commit crimes. That's because the creators of deepfakes have the power to make people say or do anything, at least on our screens. Most Americans have no idea how far the technology has come in just the last four years or the danger, disruption and opportunities that come with it.


VeriDoc Global and VIEWTRACK Form Technology Partnership

#artificialintelligence

VeriDoc Global is pleased to announce a partnership with VIEWTRACK. VIEWTRACK is a provider of IoT solutions, 4G GPS Tracking, Fleet Management, and Artificial Intelligence Solutions for business and personal assets. Headquartered and based in Brisbane, Australia, the company supplies all forms of tracking technology worldwide. The partnership will enhance existing solutions by combining cutting-edge IoT devices with blockchain technology in areas such as transport, safety and manufacturing. To find out more information about VIEWTRACK please visit https://viewtrack.com.au and for more on VeriDoc Global https://veridocglobal.com


Performance Analysis of Fractional Learning Algorithms

arXiv.org Artificial Intelligence

The least mean square (LMS) algorithms are of paramount importance in the field of signal processing since their emergence [61, 62, 60]. In particular, they are used profusely in adaptive filtering and signal analysis [27, 64, 24, 5]. The key aspects that make LMS algorithms attractive are their low complexity, stability, and an unbiased mean convergence to the so-called Wiener solution in stationary environments [48]. Unfortunately, its rate of convergence depends on the eigenvalue spread of the correlation matrix of the input signal in non-stationary environments [62, 27]. Accordingly, many variant algorithms were proposed to achieve better performance by curtailing the influence of the spectral properties of the input signal correlation matrix; see, for instance, the LMS-Newton algorithm [25], transform-domain algorithm [37], and affine projection algorithm [49]. On the other hand, a desire for computationally simpler algorithms has also led to the development of many variants such as quantized-error algorithms [6, 19, 30] and normalized LMS algorithms [65, 48, 36]. A decent list of these variant algorithms along with the details of their key features is provided in [24, Ch. 4]. We also refer to fairly recent survey articles [63, 26] on the history of adaptive filtering and the development of the LMS algorithms.


Representation of professions in entertainment media: Insights into frequency and sentiment trends through computational text analysis

arXiv.org Artificial Intelligence

Societal ideas and trends dictate media narratives and cinematic depictions which in turn influences people's beliefs and perceptions of the real world. Media portrayal of culture, education, government, religion, and family affect their function and evolution over time as people interpret and perceive these representations and incorporate them into their beliefs and actions. It is important to study media depictions of these social structures so that they do not propagate or reinforce negative stereotypes, or discriminate against any demographic section. In this work, we examine media representation of professions and provide computational insights into their incidence, and sentiment expressed, in entertainment media content. We create a searchable taxonomy of professional groups and titles to facilitate their retrieval from speaker-agnostic text passages like movie and television (TV) show subtitles. We leverage this taxonomy and relevant natural language processing (NLP) models to create a corpus of professional mentions in media content, spanning more than 136,000 IMDb titles over seven decades (1950-2017). We analyze the frequency and sentiment trends of different occupations, study the effect of media attributes like genre, country of production, and title type on these trends, and investigate if the incidence of professions in media subtitles correlate with their real-world employment statistics. We observe increased media mentions of STEM, arts, sports, and entertainment occupations in the analyzed subtitles, and a decreased frequency of manual labor jobs and military occupations. The sentiment expressed toward lawyers, police, and doctors is becoming negative over time, whereas astronauts, musicians, singers, and engineers are mentioned favorably. Professions that employ more people have increased media frequency, supporting our hypothesis that media acts as a mirror to society.


Neural Algorithmic Reasoners are Implicit Planners

arXiv.org Machine Learning

Implicit planning has emerged as an elegant technique for combining learned models of the world with end-to-end model-free reinforcement learning. We study the class of implicit planners inspired by value iteration, an algorithm that is guaranteed to yield perfect policies in fully-specified tabular environments. We find that prior approaches either assume that the environment is provided in such a tabular form -- which is highly restrictive -- or infer "local neighbourhoods" of states to run value iteration over -- for which we discover an algorithmic bottleneck effect. This effect is caused by explicitly running the planning algorithm based on scalar predictions in every state, which can be harmful to data efficiency if such scalars are improperly predicted. We propose eXecuted Latent Value Iteration Networks (XLVINs), which alleviate the above limitations. Our method performs all planning computations in a high-dimensional latent space, breaking the algorithmic bottleneck. It maintains alignment with value iteration by carefully leveraging neural graph-algorithmic reasoning and contrastive self-supervised learning. Across eight low-data settings -- including classical control, navigation and Atari -- XLVINs provide significant improvements to data efficiency against value iteration-based implicit planners, as well as relevant model-free baselines. Lastly, we empirically verify that XLVINs can closely align with value iteration.


TCube: Domain-Agnostic Neural Time-series Narration

arXiv.org Artificial Intelligence

The task of generating rich and fluent narratives that aptly describe the characteristics, trends, and anomalies of time-series data is invaluable to the sciences (geology, meteorology, epidemiology) or finance (trades, stocks, or sales and inventory). The efforts for time-series narration hitherto are domain-specific and use predefined templates that offer consistency but lead to mechanical narratives. We present TCube (Time-series-to-text), a domain-agnostic neural framework for time-series narration, that couples the representation of essential time-series elements in the form of a dense knowledge graph and the translation of said knowledge graph into rich and fluent narratives through the transfer-learning capabilities of PLMs (Pre-trained Language Models). TCube's design primarily addresses the challenge that lies in building a neural framework in the complete paucity of annotated training data for time-series. The design incorporates knowledge graphs as an intermediary for the representation of essential time-series elements which can be linearized for textual translation. To the best of our knowledge, TCube is the first investigation of the use of neural strategies for time-series narration. Through extensive evaluations, we show that TCube can improve the lexical diversity of the generated narratives by up to 65.38% while still maintaining grammatical integrity. The practicality and deployability of TCube is further validated through an expert review (n=21) where 76.2% of participating experts wary of auto-generated narratives favored TCube as a deployable system for time-series narration due to its richer narratives. Our code-base, models, and datasets, with detailed instructions for reproducibility is publicly hosted at https://github.com/Mandar-Sharma/TCube.