Institution: Aristotle University of Thessaloniki;

GreekPolitics: Sentiment Analysis on Greek Politically Charged Tweets

The rapid growth of on-line social media platforms has rendered opinion mining/sentiment analysis a critical area of research. This paper focuses on analyzing Twitter posts (tweets), written in the Greek language and politically charged in content. This is a rather underexplored topic, due to the inadequacy of publicly available annotated datasets. Thus, we present and release GreekPolitics: a dataset of Greek tweets with politically charged content, annotated for four different sentiments: polarity, figurativeness, aggressiveness and bias. GreekPolitics has been evaluated comprehensively using state-of-the-art Deep Neural Networks (DNNs) and data augmentation methods. This paper details the dataset, the evaluation process and the experimental results.

Quantifying the knowledge in Deep Neural Networks: an overview

Deep Neural Networks (DNNs) have proven to be extremely effective at learning a wide range of tasks. Due to their complexity and frequently inexplicable internal state, DNNs are difficult to analyze: their black-box nature makes it challenging for humans to comprehend their internal behavior. Several attempts to interpret their operation have been made during the last decade, but analyzing deep neural models from the perspective of the knowledge encoded in their layers is a very promising research direction, which has barely been touched upon. Such a research approach could provide a more accurate insight into a DNN model, its internal state, learning progress, and knowledge
storage capabilities. The purpose of this survey is two-fold: a) to review the concept of DNN knowledge quantification and highlight it as an important near-future challenge, as well as b) to provide a brief account of the scant existing methods attempting to actually quantify DNN knowledge. Although a few such algorithms have been proposed, this is an emerging topic still under investigation.

Political Tweet Sentiment Analysis For Public Opinion Polling

Public opinion measurement through polling is a classical political analysis task, e.g. for predicting national and local election results. However, polls are expensive to run and their results may be biased primarily due to improper population sampling. In this paper, we propose two innovative methods for employing tweet sentiment analysis’ results for public opinion polling. Our first method utilizes merely the tweet sentiment analysis’ results outperforming a plethora of well-recognised methods. In addition, we introduce a novel hybrid way to estimate electorally results from both public opinion polls and tweets. This method enables more accurate, frequent and inexpensive public opinion estimation and used for estimating the result of the 2023 Greek national election. Our method managed to achieve lower deviation than the conventional public opinion polls from the actual election’s results, introducing new possibilities for public opinion estimation using social media platforms.

Towards Human Society-inspired Decentralized DNN Inference

In human societies, individuals make their own decisions and they may select if and who may influence it, by e.g., consulting with people of their acquaintance or experts of a field. At a societal level, the overall knowledge is preserved and enhanced by individual person empowerment, where complicated consensus protocols have been developed over time in the form of societal mechanisms to assess, weight, combine and isolate individual people opinions. In distributed machine learning environments however, individual AI agents are merely part of a system where decisions are made in a centralized and aggregated fashion or require a fixed network topology, a practice prone to security risks and collaboration is nearly absent. For instance, Byzantine Failures may tamper both the training and inference stage of individual AI agents, leading to significantly reduced overall system performance. Inspired by societal practices, we propose a decentralized inference strategy where each individual agent is empowered to make their own decisions, by exchanging and aggregating information with other agents in their network. To this end, a ”Quality of Inference” consensus protocol (QoI) is proposed, forming a single commonly accepted inference rule applied by every individual agent. The overall system knowledge and decisions on specific manners can thereby be stored by all individual agents in a decentralized fashion, employing e.g., blockchain technology. Our experiments in classification tasks indicate that the proposed approach forms a secure decentralized inference framework, that prevents adversaries at tampering the overall process and achieves comparable performance with centralized decision aggregation methods.

Deep Reinforcement Learning with semi-expert distillation for autonomous UAV cinematography

Unmanned Aerial Vehicles (UAVs, or drones) have revolutionized modern media production. Being rapidly deployable “flying cameras”, they can easily capture aesthetically pleasing aerial footage of static or moving filming targets/subjects. Current approaches rely either on manual UAV/gimbal control by human experts or on a combination of complex computer vision algorithms and hardware configurations for automating the flight+flying process. This paper explores an efficient Deep Reinforcement Learning (DRL) alternative, which implicitly merges the target detection and path planning steps into a single algorithm. To achieve this, a baseline DRL approach is augmented with a novel policy distillation component, which transfers knowledge from a suitable, semi-expert Model Predictive Control (MPC) controller into the DRL agent. Thus, the latter is able to autonomously execute a specific UAV cinematography task with purely visual input. Unlike the MPC controller, the proposed DRL agent does not need to know the 3D world position of the filming target during inference. Experiments conducted in a photorealistic simulator showcase superior performance and training speed compared to the baseline agent while surpassing the MPC controller in terms of visual occlusion avoidance.

Knowledge Distillation-driven Communication Framework for Neural Networks: Enabling Efficient Student-Teacher Interactions

This paper presents a novel framework for facilitating communication and knowledge exchange among neural networks, leveraging the roles of both students and teachers. In our proposed framework, each node represents a neural network, capable of acting as either a student or a teacher. When new data is introduced and a network has not been trained on it, the node assumes the role of a student, initiating a communication process. The student node communicates with potential teachers, identifying those networks that have already been trained on the incoming data. Subsequently, the student node employs knowledge distillation techniques to learn from the teachers and gain insights from their accumulated knowledge. This approach enables efficient and effective knowledge transfer within the neural network ecosystem, enhancing learning capabilities and fostering collaboration among diverse networks. Experimental results demonstrate the efficacy of our framework in improving overall network performance and knowledge utilization.

Temporal Normalization in Attentive Key-frame Extraction for Deep Neural Video Summarization

Attention-based neural architectures have consistently demonstrated superior performance over Long Short-Term Memory (LSTM) Deep Neural Networks (DNNs) in tasks such as key-frame extraction for video summarization. However, existing approaches mostly rely on rather shallow Transformer DNNs. This paper revisits the issue of model depth and proposes DATS: a deep attentive architecture for supervised video summarization that meaningfully exploits skip connections. Additionally, a novel per-layer temporal normalization algorithm is proposed that yields improved test accuracy. Finally, the model’s noisy output is rectified in an innovative post-processing step. Experiments conducted on two common, publicly available benchmark datasets showcase performance superior to competing state-of-the-art video summarization methods, both supervised and unsupervised.