pwc-archive/papers-with-abstracts huggingface dataset:
MIQCQP reformulation of the ReLU neural networks Lipschitz constant estimation problem
Authors: Mohammed Sbihi, Sophie Jan, Nicolas Couellan
Date: 2024-02-02 00:00:00

It is well established that to ensure or certify the robustness of a neural network, its Lipschitz constant plays a prominent role. However, its calculation is NP-hard. In this note, by taking into account activation regions at each layer as new constraints, we propose new quadratically constrained MIP formulations for the neural network Lipschitz estimation problem. The solutions of these problems give lower bounds and upper bounds of the Lipschitz constant and we detail conditions when they coincide with the exact Lipschitz constant.
Improving Sequential Recommendations with LLMs
Authors: Artun Boz, Wouter Zorgdrager, Zoe Kotti, Jesse Harte, Panos Louridas, Dietmar Jannach, Vassilios Karakoidas, Marios Fragkoulis
Date: 2024-02-02 00:00:00
Tasks: Sequential Recommendation

The sequential recommendation problem has attracted considerable research attention in the past few years, leading to the rise of numerous recommendation models. In this work, we explore how Large Language Models (LLMs), which are nowadays introducing disruptive effects in many AI-based applications, can be used to build or improve sequential recommendation approaches. Specifically, we design three orthogonal approaches and hybrids of those to leverage the power of LLMs in different ways. In addition, we investigate the potential of each approach by focusing on its comprising technical aspects and determining an array of alternative choices for each one. We conduct extensive experiments on three datasets and explore a large variety of configurations, including different language models and baseline recommendation models, to obtain a comprehensive picture of the performance of each approach. Among other observations, we highlight that initializing state-of-the-art sequential recommendation models such as BERT4Rec or SASRec with embeddings obtained from an LLM can lead to substantial performance gains in terms of accuracy. Furthermore, we find that fine-tuning an LLM for recommendation tasks enables it to learn not only the tasks, but also concepts of a domain to some extent. We also show that fine-tuning OpenAI GPT leads to considerably better performance than fine-tuning Google PaLM 2. Overall, our extensive experiments indicate a huge potential value of leveraging LLMs in future recommendation approaches. We publicly share the code and data of our experiments to ensure reproducibility.
Minimizing Regret in Billboard Advertisement under Zonal Influence Constraint
Authors: Dildar Ali, Suman Banerjee, Yamuna Prasad
Date: 2024-02-02 00:00:00

In a typical billboard advertisement technique, a number of digital billboards are owned by an influence provider, and many advertisers approach the influence provider for a specific number of views of their advertisement content on a payment basis. If the influence provider provides the demanded or more influence, then he will receive the full payment or else a partial payment. In the context of an influence provider, if he provides more or less than an advertiser's demanded influence, it is a loss for him. This is formalized as 'Regret', and naturally, in the context of the influence provider, the goal will be to allocate the billboard slots among the advertisers such that the total regret is minimized. In this paper, we study this problem as a discrete optimization problem and propose four solution approaches. The first one selects the billboard slots from the available ones in an incremental greedy manner, and we call this method the Budget Effective Greedy approach. In the second one, we introduce randomness with the first one, where we perform the marginal gain computation for a sample of randomly chosen billboard slots. The remaining two approaches are further improvements over the second one. We analyze all the algorithms to understand their time and space complexity. We implement them with real-life trajectory and billboard datasets and conduct a number of experiments. It has been observed that the randomized budget effective greedy approach takes reasonable computational time while minimizing the regret.
RimiRec: Modeling Refined Multi-interest in Hierarchical Structure for Recommendation
Authors: Haolei Pei, Yuanyuan Xu, Yangping Zhu, Yuan Nie
Date: 2024-02-02 00:00:00
Tasks: Recommendation Systems, Retrieval

Industrial recommender systems usually consist of the retrieval stage and the ranking stage, to handle the billion-scale of users and items. The retrieval stage retrieves candidate items relevant to user interests for recommendations and has attracted much attention. Frequently, a user shows refined multi-interests in a hierarchical structure. For example, a user likes Conan and Kuroba Kaito, which are the roles in hierarchical structure "Animation, Japanese Animation, Detective Conan". However, most existing methods ignore this hierarchical nature, and simply average the fine-grained interest information. Therefore, we propose a novel two-stage approach to explicitly modeling refined multi-interest in a hierarchical structure for recommendation. In the first hierarchical multi-interest mining stage, the hierarchical clustering and transformer-based model adaptively generate circles or sub-circles that users are interested in. In the second stage, the partition of retrieval space allows the EBR models to deal only with items within each circle and accurately capture users' refined interests. Experimental results show that the proposed approach achieves state-of-the-art performance. Our framework has also been deployed at Lofter.
TransFR: Transferable Federated Recommendation with Pre-trained Language Models
Authors: Honglei Zhang, He Liu, Haoxuan Li, Yidong Li
Date: 2024-02-02 00:00:00
Tasks: Privacy Preserving

Federated recommendations (FRs), facilitating multiple local clients to collectively learn a global model without disclosing user private data, have emerged as a prevalent architecture for privacy-preserving recommendations. In conventional FRs, a dominant paradigm is to utilize discrete identities to represent users/clients and items, which are subsequently mapped to domain-specific embeddings to participate in model training. Despite considerable performance, we reveal three inherent limitations that can not be ignored in federated settings, i.e., non-transferability across domains, unavailability in cold-start settings, and potential privacy violations during federated training. To this end, we propose a transferable federated recommendation model with universal textual representations, TransFR, which delicately incorporates the general capabilities empowered by pre-trained language models and the personalized abilities by fine-tuning local private data. Specifically, it first learns domain-agnostic representations of items by exploiting pre-trained models with public textual corpora. To tailor for federated recommendation, we further introduce an efficient federated fine-tuning and a local training mechanism. This facilitates personalized local heads for each client by utilizing their private behavior data. By incorporating pre-training and fine-tuning within FRs, it greatly improves the adaptation efficiency transferring to a new domain and the generalization capacity to address cold-start issues. Through extensive experiments on several datasets, we demonstrate that our TransFR model surpasses several state-of-the-art FRs in terms of accuracy, transferability, and privacy.
CF4J: Collaborative Filtering for Java
Authors: Fernando Ortega, Bo Zhu, Jesus Bobadilla, Antonio Hernando
Date: 2024-02-01 00:00:00
Tasks: Collaborative Filtering, Recommendation Systems

Recommender Systems (RS) provide a relevant tool to mitigate the information overload problem. A large number of researchers have published hundreds of papers to improve different RS features. It is advisable to use RS frameworks that simplify RS researchers: a) to design and implement recommendations methods and, b) to speed up the execution time of the experiments. In this paper, we present CF4J, a Java library designed to carry out Collaborative Filtering based RS research experiments. CF4J has been designed from researchers to researchers. It allows: a) RS datasets reading, b) full and easy access to data and intermediate or final results, c) to extend their main functionalities, d) to concurrently execute the implemented methods, and e) to provide a thorough evaluation for the implementations by quality measures. In summary, CF4J serves as a library specifically designed for the research trial and error process.
Graph Representation Learning for Contention and Interference Management in Wireless Networks
Authors: Zhouyou Gu, Branka Vucetic, Kishore Chikkam, Pasquale Aliberti, Wibowo Hardjawana
Date: 2024-01-15 00:00:00
Tasks: graph construction, Graph Representation Learning, Management, Representation Learning

Restricted access window (RAW) in Wi-Fi 802.11ah networks manages contention and interference by grouping users and allocating periodic time slots for each group's transmissions. We will find the optimal user grouping decisions in RAW to maximize the network's worst-case user throughput. We review existing user grouping approaches and highlight their performance limitations in the above problem. We propose formulating user grouping as a graph construction problem where vertices represent users and edge weights indicate the contention and interference. This formulation leverages the graph's max cut to group users and optimizes edge weights to construct the optimal graph whose max cut yields the optimal grouping decisions. To achieve this optimal graph construction, we design an actor-critic graph representation learning (AC-GRL) algorithm. Specifically, the actor neural network (NN) is trained to estimate the optimal graph's edge weights using path losses between users and access points. A graph cut procedure uses semidefinite programming to solve the max cut efficiently and return the grouping decisions for the given weights. The critic NN approximates user throughput achieved by the above-returned decisions and is used to improve the actor. Additionally, we present an architecture that uses the online-measured throughput and path losses to fine-tune the decisions in response to changes in user populations and their locations. Simulations show that our methods achieve $30\%\sim80\%$ higher worst-case user throughput than the existing approaches and that the proposed architecture can further improve the worst-case user throughput by $5\%\sim30\%$ while ensuring timely updates of grouping decisions.
Spoof Trace Disentanglement for generic face antispoofing
Authors: Yaojie Liu and Xiaoming Liu, Member, IEEE
Date: 2023-03-03 00:00:00
Proceeding: journal 2023 3
Tasks: Data Augmentation, Disentanglement, Face Anti-Spoofing

Prior studies show that the key to face anti-spoofing lies in the subtle image patterns, termed “spoof trace,” e.g., color
distortion, 3D mask edge, and Moire pattern. Spoof detection rooted on those spoof traces can improve not only the model’s 
generalization but also the interpretability. Yet, it is a challenging task due to the diversity of spoof attacks and the lack of ground truth
for spoof traces. In this work, we propose a novel adversarial learning framework to explicitly estimate the spoof related patterns for
face anti-spoofing. Inspired by the physical process, spoof faces are disentangled into spoof traces and the live counterparts in two
steps: additive step and inpainting step. This two-step modeling can effectively narrow down the searching space for adversarial
learning of spoof trace. Based on the trace modeling, the disentangled spoof traces can be utilized to reversely construct new spoof
faces, which is used as data augmentation to effectively tackle long-tail spoof types. In addition, we apply frequency-based image
decomposition in both the input and disentangled traces to better reflect the low-level vision cues. Our approach demonstrates superior
spoof detection performance on 3 testing scenarios: known attacks, unknown attacks, and open-set attacks. Meanwhile, it provides a
visually-convincing estimation of the spoof traces. Source code and pre-trained models will be publicly available upon publication.
Multi-Agent Reinforcement Learning Resources Allocation Method Using Dueling Double Deep Q-Network in Vehicular Networks
Authors: Yuxin Ji; Yu Wang; Haitao Zhao; Guan Gui; Haris Gacanin; Hikmet Sari; Fumiyuki Adachi
Date: 2023-05-12 00:00:00
Proceeding: IEEE Transactions on Vehicular Technology 2023 5
Tasks: Data Interaction, Multi-agent Reinforcement Learning, Reinforcement Learning (RL)

The communications between vehicle-to-vehicle (V2V) with high frequency, group sending, group receiving and periodic lead to serious collision of wireless resources and limited system capacity, and the rapid channel changes in high mobility vehicular environments preclude the possibility of collecting accurate instantaneous channel state information at the base station for centralized resource management. For the Internet of Vehicles (IoV), it is a fundamental challenge to achieve low latency and high reliability communication for real-time data interaction over short distances in a complex wireless propagation environment, as well as to attenuate and avoid inter-vehicle interference in the region through a reasonable spectrum allocation. To solve the above problems, this paper proposes a resource allocation (RA) method using dueling double deep Q-network reinforcement learning (RL) with low-dimensional fingerprints and soft-update architecture (D3QN-LS) while constructing a multi-agent model based on a Manhattan grid layout urban virtual environment, with communication links between V2V links acting as agents to reuse vehicle-to-infrastructure (V2I) spectrum resources. In addition, we extend the amount of transmitted data in our work, while adding scenarios where spectrum resources are relatively scarce, i.e. the number of V2V links is significantly larger than the amount of spectrum, to compensate for some of the shortcomings in existing literature studies. We demonstrate that the proposed D3QN-LS algorithm leads to a further improvement in the total capacity of V2I links and the success rate of periodic secure message transmission in V2V links.
Brain Computer Interface: Deep Learning Approach to Predict Human Emotion Recognition
Date: 2022-11-18 00:00:00
Tasks: Brain Computer Interface, EEG, Emotion Recognition

Brain-Computer Interfaces allow controlling machines through signals coming from Electroencephalography (EEG) analysis. Nowadays, there are several cheap electroencephalographs available on the market that guarantee good quality EEG signals. A very interesting approach in this area is related to detecting the emotional states of a user through the analysis of her EEG signal. In our study, we tried to detect the emotional polarity (Valence), the state of emotional excitement (Arousal), and the level of emotion control (Dominance). Through metric interpolation and Russell’s circumplex model, it is possible to characterize and define the current emotional state of the user who wears the device. Our study presents a prototype of an EEG-based emotion recognizer that provides the user’s emotional state exploitable as bio-feedback.
Efficient compilation of expressive problem space specifications to neural network solvers
Authors: Matthew L. Daggitt, Wen Kokke, Robert Atkey
Date: 2024-01-24 00:00:00

Recent work has described the presence of the embedding gap in neural network verification. On one side of the gap is a high-level specification about the network's behaviour, written by a domain expert in terms of the interpretable problem space. On the other side are a logically-equivalent set of satisfiability queries, expressed in the uninterpretable embedding space in a form suitable for neural network solvers. In this paper we describe an algorithm for compiling the former to the latter. We explore and overcome complications that arise from targeting neural network solvers as opposed to standard SMT solvers.
On the Interplay of Artificial Intelligence and Space-Air-Ground Integrated Networks: A Survey
Authors: Adilya Bakambekova, Nour Kouzayha, Tareq Al-Naffouri
Date: 2024-01-20 00:00:00
Tasks: Decision Making

Space-Air-Ground Integrated Networks (SAGINs), which incorporate space and aerial networks with terrestrial wireless systems, are vital enablers of the emerging sixth-generation (6G) wireless networks. Besides bringing significant benefits to various applications and services, SAGINs are envisioned to extend high-speed broadband coverage to remote areas, such as small towns or mining sites, or areas where terrestrial infrastructure cannot reach, such as airplanes or maritime use cases. However, due to the limited power and storage resources, as well as other constraints introduced by the design of terrestrial networks, SAGINs must be intelligently configured and controlled to satisfy the envisioned requirements. Meanwhile, Artificial Intelligence (AI) is another critical enabler of 6G. Due to massive amounts of available data, AI has been leveraged to address pressing challenges of current and future wireless networks. By adding AI and facilitating the decision-making and prediction procedures, SAGINs can effectively adapt to their surrounding environment, thus enhancing the performance of various metrics. In this work, we aim to investigate the interplay of AI and SAGINs by providing a holistic overview of state-of-the-art research in AI-enabled SAGINs. Specifically, we present a comprehensive overview of some potential applications of AI in SAGINs. We also cover open issues in employing AI and detail the contributions of SAGINs in the development of AI. Finally, we highlight some limitations of the existing research works and outline potential future research directions.
Radio Map Estimation -- An Open Dataset with Directive Transmitter Antennas and Initial Experiments
Authors: Fabian Jaensch, Giuseppe Caire, Begüm Demir
Date: 2024-01-12 00:00:00

Over the last years, several works have explored the application of deep learning algorithms to determine the large-scale signal fading (also referred to as ``path loss'') between transmitter and receiver pairs in urban communication networks. The central idea is to replace costly measurement campaigns, inaccurate statistical models or computationally expensive ray-tracing simulations by machine learning models which, once trained, produce accurate predictions almost instantly. Although the topic has attracted attention from many researchers, there are few open benchmark datasets and codebases that would allow everyone to test and compare the developed methods and algorithms. We take a step towards filling this gap by releasing a publicly available dataset of simulated path loss radio maps together with realistic city maps from real-world locations and aerial images from open datasources. Initial experiments regarding model architectures, input feature design and estimation of radio maps from aerial images are presented and the code is made available.
Building Blocks to Empower Cognitive Internet with Hybrid Edge Cloud
Authors: Siavash Alamouti, Fay Arjomandi, Michel Burger, Dr. Bashar Altakrouri
Date: 2024-01-10 00:00:00
Tasks: Decision Making

As we transition from the mobile internet to the 'Cognitive Internet,' a significant shift occurs in how we engage with technology and intelligence. We contend that the Cognitive Internet goes beyond the Cognitive Internet of Things (Cognitive IoT), enabling connected objects to independently acquire knowledge and understanding. Unlike the Mobile Internet and Cognitive IoT, the Cognitive Internet integrates collaborative intelligence throughout the network, blending the cognitive IoT realm with system-wide collaboration and human intelligence. This integrated intelligence facilitates interactions between devices, services, entities, and individuals across diverse domains while preserving decision-making autonomy and accommodating various identities. The paper delves into the foundational elements, distinct characteristics, benefits, and industrial impact of the 'Cognitive Internet' paradigm. It highlights the importance of adaptable AI infrastructures and hybrid edge cloud (HEC) platforms in enabling this shift. This evolution brings forth cognitive services, a Knowledge as a Service (KaaS) economy, enhanced decision-making autonomy, sustainable digital progress, advancements in data management, processing techniques, and a stronger emphasis on privacy. In essence, this paper serves as a crucial resource for understanding and leveraging the transformative potential of HEC for Cognitive Internet. Supported by case studies, forward-looking perspectives, and real-world applications, it provides comprehensive insights into this emerging paradigm.
dRG-MEC: Decentralized Reinforced Green Offloading for MEC-enabled Cloud Network
Authors: Asad Aftab, Semeen Rehman
Date: 2024-01-10 00:00:00
Tasks: Edge-computing

Multi-access-Mobile Edge Computing (MEC) is a promising solution for computationally demanding rigorous applications, that can meet 6G network service requirements. However, edge servers incur high computation costs during task processing. In this paper, we proposed a technique to minimize the total computation and communication overhead for optimal resource utilization with joint computational offloading that enables a green environment. Our optimization problem is NP-hard; thus, we proposed a decentralized Reinforcement Learning (dRL) approach where we eliminate the problem of dimensionality and over-estimation of the value functions. Compared to baseline schemes our technique achieves a 37.03% reduction in total system costs.
Neural Models and Algorithms for Sensorimotor Control of an Octopus Arm
Authors: Tixian Wang, Udit Halder, Ekaterina Gribkova, Rhanor Gillette, Mattia Gazzola, Prashant G. Mehta
Date: 2024-02-02 00:00:00

In this article, a biophysically realistic model of a soft octopus arm with internal musculature is presented. The modeling is motivated by experimental observations of sensorimotor control where an arm localizes and reaches a target. Major contributions of this article are: (i) development of models to capture the mechanical properties of arm musculature, the electrical properties of the arm peripheral nervous system (PNS), and the coupling of PNS with muscular contractions; (ii) modeling the arm sensory system, including chemosensing and proprioception; and (iii) algorithms for sensorimotor control, which include a novel feedback neural motor control law for mimicking target-oriented arm reaching motions, and a novel consensus algorithm for solving sensing problems such as locating a food source from local chemical sensory information (exogenous) and arm deformation information (endogenous). Several analytical results, including rest-state characterization and stability properties of the proposed sensing and motor control algorithms, are provided. Numerical simulations demonstrate the efficacy of our approach. Qualitative comparisons against observed arm rest shapes and target-oriented reaching motions are also reported.