Search Results for author: Fabrizio Silvestri

Found 59 papers, 22 papers with code

STLight: a Fully Convolutional Approach for Efficient Predictive Learning by Spatio-Temporal joint Processing

no code implementations15 Nov 2024 Andrea Alfarano, Alberto Alfarano, Linda Friso, Andrea Bacciu, Irene Amerini, Fabrizio Silvestri

Spatio-Temporal predictive Learning is a self-supervised learning paradigm that enables models to identify spatial and temporal patterns by predicting future frames based on past frames.

Computational Efficiency Self-Supervised Learning

A Theoretical Analysis of Recommendation Loss Functions under Negative Sampling

no code implementations12 Nov 2024 Giulia Di Teodoro, Federico Siciliano, Nicola Tonellotto, Fabrizio Silvestri

We show that the BPR bound on NDCG is weaker than that of BCE, contradicting the common assumption that BPR is superior to BCE in RSs training.

Recommendation Systems

ATM: Improving Model Merging by Alternating Tuning and Merging

no code implementations5 Nov 2024 Luca Zhou, Daniele Solombrino, Donato Crisostomi, Maria Sofia Bucarelli, Fabrizio Silvestri, Emanuele Rodolà

Building on this insight, we propose viewing model merging as a single step in an iterative process that Alternates between Tuning and Merging (ATM).

Task Arithmetic

Beyond position: how rotary embeddings shape representations and memory in autoregressive transfomers

no code implementations23 Oct 2024 Valeria Ruscio, Fabrizio Silvestri

Rotary Positional Embeddings (RoPE) enhance positional encoding in Transformer models, yet their full impact on model dynamics remains underexplored.

Position

Eco-Aware Graph Neural Networks for Sustainable Recommendations

1 code implementation12 Oct 2024 Antonio Purificato, Fabrizio Silvestri

Recommender systems play a crucial role in alleviating information overload by providing personalized recommendations tailored to users' preferences and interests.

Recommendation Systems

Natural Language Counterfactual Explanations for Graphs Using Large Language Models

1 code implementation11 Oct 2024 Flavio Giorgi, Cesare Campagnano, Fabrizio Silvestri, Gabriele Tolomei

Explainable Artificial Intelligence (XAI) has emerged as a critical area of research to unravel the opaque inner logic of (deep) machine learning models.

counterfactual Explainable artificial intelligence +2

A Reproducible Analysis of Sequential Recommender Systems

1 code implementation7 Aug 2024 Filippo Betello, Antonio Purificato, Federico Siciliano, Giovanni Trappolini, Andrea Bacciu, Nicola Tonellotto, Fabrizio Silvestri

By leveraging sequential data, SRSs can identify temporal patterns in user behaviour, significantly improving recommendation accuracy and relevance. Ensuring the reproducibility of these models is paramount for advancing research and facilitating comparisons between them.

Experimental Design Recommendation Systems

A Tale of Trust and Accuracy: Base vs. Instruct LLMs in RAG Systems

1 code implementation21 Jun 2024 Florin Cuconasu, Giovanni Trappolini, Nicola Tonellotto, Fabrizio Silvestri

Retrieval Augmented Generation (RAG) represents a significant advancement in artificial intelligence combining a retrieval phase with a generative phase, with the latter typically being powered by large language models (LLMs).

RAG Retrieval +1

Predicting Award Winning Research Papers at Publication Time

no code implementations18 Jun 2024 Riccardo Vella, Andrea Vitaletti, Fabrizio Silvestri

We made our experiments considering the ArnetMiner citation graph, while the ground truth on award-winning papers has been obtained from a collection of best paper awards from 32 computer science conferences.

Graph Neural Re-Ranking via Corpus Graph

no code implementations17 Jun 2024 Andrea Giuseppe Di Francesco, Christian Giannetti, Nicola Tonellotto, Fabrizio Silvestri

Re-ranking systems aim to reorder an initial list of documents to satisfy better the information needs associated with a user-provided query.

Re-Ranking

Generating Query Recommendations via LLMs

no code implementations30 May 2024 Andrea Bacciu, Enrico Palumbo, Andreas Damianou, Nicola Tonellotto, Fabrizio Silvestri

We then improved our system by proposing a version that exploits query logs called Retriever-Augmented GQR (RA-GQR).

Recommendation Systems

Debiasing Machine Unlearning with Counterfactual Examples

no code implementations24 Apr 2024 Ziheng Chen, Jia Wang, Jun Zhuang, Abbavaram Gowtham Reddy, Fabrizio Silvestri, Jin Huang, Kaushiki Nag, Kun Kuang, Xin Ning, Gabriele Tolomei

This bias emerges from two main sources: (1) data-level bias, characterized by uneven data removal, and (2) algorithm-level bias, which leads to the contamination of the remaining dataset, thereby degrading model accuracy.

counterfactual Machine Unlearning

$\nabla τ$: Gradient-based and Task-Agnostic machine Unlearning

no code implementations21 Mar 2024 Daniel Trippa, Cesare Campagnano, Maria Sofia Bucarelli, Gabriele Tolomei, Fabrizio Silvestri

In this study, we introduce Gradient-based and Task-Agnostic machine Unlearning ($\nabla \tau$), an optimization framework designed to remove the influence of a subset of training data efficiently.

Inference Attack Machine Unlearning +1

Link Prediction under Heterophily: A Physics-Inspired Graph Neural Network Approach

no code implementations22 Feb 2024 Andrea Giuseppe Di Francesco, Francesco Caso, Maria Sofia Bucarelli, Fabrizio Silvestri

Physics-Inspired GNNs such as GRAFF provided a significant contribution to enhance node classification performance under heterophily, thanks to the adoption of physics biases in the message-passing.

Graph Neural Network Link Prediction +1

The Power of Noise: Redefining Retrieval for RAG Systems

2 code implementations26 Jan 2024 Florin Cuconasu, Giovanni Trappolini, Federico Siciliano, Simone Filice, Cesare Campagnano, Yoelle Maarek, Nicola Tonellotto, Fabrizio Silvestri

Retrieval-Augmented Generation (RAG) has recently emerged as a method to extend beyond the pre-trained knowledge of Large Language Models by augmenting the original prompt with relevant passages or documents retrieved by an Information Retrieval (IR) system.

Information Retrieval RAG +2

A topological description of loss surfaces based on Betti Numbers

no code implementations8 Jan 2024 Maria Sofia Bucarelli, Giuseppe Alessio D'Inverno, Monica Bianchini, Franco Scarselli, Fabrizio Silvestri

In the context of deep learning models, attention has recently been paid to studying the surface of the loss function in order to better understand training with methods based on gradient descent.

Enhancing Content Moderation with Culturally-Aware Models

no code implementations5 Dec 2023 Alex J. Chan, José Luis Redondo García, Fabrizio Silvestri, Colm O'Donnell, Konstantina Palla

Our findings reinforce the need for an adaptable content moderation approach that remains flexible in response to the diverse cultural landscapes it operates in and represents a step towards a more equitable and culturally sensitive framework for content moderation, demonstrating what is achievable in this domain.

Decision Making Decoder +1

Evading Community Detection via Counterfactual Neighborhood Search

no code implementations13 Oct 2023 Andrea Bernini, Fabrizio Silvestri, Gabriele Tolomei

Community detection techniques are useful for social media platforms to discover tightly connected groups of users who share common interests.

Community Detection counterfactual +2

Investigating the Robustness of Sequential Recommender Systems Against Training Data Perturbations

no code implementations24 Jul 2023 Filippo Betello, Federico Siciliano, Pushkar Mishra, Fabrizio Silvestri

However, their robustness in the face of perturbations in training data remains a largely understudied yet critical issue.

Recommendation Systems

RRAML: Reinforced Retrieval Augmented Machine Learning

no code implementations24 Jul 2023 Andrea Bacciu, Florin Cuconasu, Federico Siciliano, Fabrizio Silvestri, Nicola Tonellotto, Giovanni Trappolini

The emergence of large language models (LLMs) has revolutionized machine learning and related fields, showcasing remarkable abilities in comprehending, generating, and manipulating human language.

Retrieval

Renormalized Graph Neural Networks

no code implementations1 Jun 2023 Francesco Caso, Giovanni Trappolini, Andrea Bacciu, Pietro Liò, Fabrizio Silvestri

It is recognized as the preferred lens through which to study complex systems, offering a framework that can untangle their intricate dynamics.

Integrating Item Relevance in Training Loss for Sequential Recommender Systems

no code implementations18 May 2023 Andrea Bacciu, Federico Siciliano, Nicola Tonellotto, Fabrizio Silvestri

Sequential Recommender Systems (SRSs) are a popular type of recommender system that learns from a user's history to predict the next item they are likely to interact with.

Recommendation Systems

Multimodal Neural Databases

1 code implementation2 May 2023 Giovanni Trappolini, Andrea Santilli, Emanuele Rodolà, Alon Halevy, Fabrizio Silvestri

The rise in loosely-structured data available through text, images, and other modalities has called for new ways of querying them.

Information Retrieval Multimodal Deep Learning +1

The Dark Side of Explanations: Poisoning Recommender Systems with Counterfactual Examples

no code implementations30 Apr 2023 Ziheng Chen, Fabrizio Silvestri, Jia Wang, Yongfeng Zhang, Gabriele Tolomei

By reversing the learning process of the recommendation model, we thus develop a proficient greedy algorithm to generate fabricated user profiles and their associated interaction records for the aforementioned surrogate model.

counterfactual Counterfactual Explanation +4

Sheaf4Rec: Sheaf Neural Networks for Graph-based Recommender Systems

1 code implementation7 Apr 2023 Antonio Purificato, Giulia Cassarà, Federico Siciliano, Pietro Liò, Fabrizio Silvestri

GNNs have proven to be effective in addressing the challenges posed by recommendation systems by efficiently modeling graphs in which nodes represent users or items and edges denote preference relationships.

Collaborative Filtering Link Prediction +1

Learning with Noisy Labels through Learnable Weighting and Centroid Similarity

2 code implementations16 Mar 2023 Farooq Ahmad Wani, Maria Sofia Bucarelli, Fabrizio Silvestri

We introduce a novel method for training machine learning models in the presence of noisy labels, which are prevalent in domains such as medical diagnosis and autonomous driving and have the potential to degrade a model's generalization performance.

Autonomous Driving Learning with noisy labels +1

Attention-likelihood relationship in transformers

1 code implementation15 Mar 2023 Valeria Ruscio, Valentino Maiorca, Fabrizio Silvestri

We analyze how large language models (LLMs) represent out-of-context words, investigating their reliance on the given context to capture their semantics.

Sparse Vicious Attacks on Graph Neural Networks

1 code implementation20 Sep 2022 Giovanni Trappolini, Valentino Maiorca, Silvio Severino, Emanuele Rodolà, Fabrizio Silvestri, Gabriele Tolomei

In this work, we focus on a specific, white-box attack to GNN-based link prediction models, where a malicious node aims to appear in the list of recommended nodes for a given target victim.

Link Prediction Recommendation Systems

GREASE: Generate Factual and Counterfactual Explanations for GNN-based Recommendations

no code implementations4 Aug 2022 Ziheng Chen, Fabrizio Silvestri, Jia Wang, Yongfeng Zhang, Zhenhua Huang, Hongshik Ahn, Gabriele Tolomei

Although powerful, it is very difficult for a GNN-based recommender system to attach tangible explanations of why a specific item ends up in the list of suggestions for a given user.

counterfactual Graph Classification +1

Detecting and Understanding Harmful Memes: A Survey

1 code implementation9 May 2022 Shivam Sharma, Firoj Alam, Md. Shad Akhtar, Dimitar Dimitrov, Giovanni Da San Martino, Hamed Firooz, Alon Halevy, Fabrizio Silvestri, Preslav Nakov, Tanmoy Chakraborty

One interesting finding is that many types of harmful memes are not really studied, e. g., such featuring self-harm and extremism, partly due to the lack of suitable datasets.

Survey

ReLAX: Reinforcement Learning Agent eXplainer for Arbitrary Predictive Models

1 code implementation22 Oct 2021 Ziheng Chen, Fabrizio Silvestri, Jia Wang, He Zhu, Hongshik Ahn, Gabriele Tolomei

However, existing CF generation methods either exploit the internals of specific models or depend on each sample's neighborhood, thus they are hard to generalize for complex models and inefficient for large datasets.

counterfactual Decision Making +4

Detecting Propaganda Techniques in Memes

1 code implementation ACL 2021 Dimitar Dimitrov, Bishr Bin Ali, Shaden Shaar, Firoj Alam, Fabrizio Silvestri, Hamed Firooz, Preslav Nakov, Giovanni Da San Martino

We further create and release a new corpus of 950 memes, carefully annotated with 22 propaganda techniques, which can appear in the text, in the image, or in both.

Database Reasoning Over Text

1 code implementation ACL 2021 James Thorne, Majid Yazdani, Marzieh Saeidi, Fabrizio Silvestri, Sebastian Riedel, Alon Halevy

Neural models have shown impressive performance gains in answering queries from natural language text.

SemEval-2021 Task 6: Detection of Persuasion Techniques in Texts and Images

1 code implementation SEMEVAL 2021 Dimitar Dimitrov, Bishr Bin Ali, Shaden Shaar, Firoj Alam, Fabrizio Silvestri, Hamed Firooz, Preslav Nakov, Giovanni Da San Martino

We describe SemEval-2021 task 6 on Detection of Persuasion Techniques in Texts and Images: the data, the annotation guidelines, the evaluation setup, the results, and the participating systems.

CycleDRUMS: Automatic Drum Arrangement For Bass Lines Using CycleGAN

no code implementations1 Apr 2021 Giorgio Barnabò, Giovanni Trappolini, Lorenzo Lastilla, Cesare Campagnano, Angela Fan, Fabio Petroni, Fabrizio Silvestri

The two main research threads in computer-based music generation are: the construction of autonomous music-making systems, and the design of computer-based environments to assist musicians.

Image-to-Image Translation Music Generation +2

CF-GNNExplainer: Counterfactual Explanations for Graph Neural Networks

1 code implementation5 Feb 2021 Ana Lucic, Maartje ter Hoeve, Gabriele Tolomei, Maarten de Rijke, Fabrizio Silvestri

In this work, we propose a method for generating CF explanations for GNNs: the minimal perturbation to the input (graph) data such that the prediction changes.

counterfactual

Neural Databases

no code implementations14 Oct 2020 James Thorne, Majid Yazdani, Marzieh Saeidi, Fabrizio Silvestri, Sebastian Riedel, Alon Halevy

We describe NeuralDB, a database system with no pre-defined schema, in which updates and queries are given in natural language.

Management

Interpretable Predictions of Tree-based Ensembles via Actionable Feature Tweaking

3 code implementations20 Jun 2017 Gabriele Tolomei, Fabrizio Silvestri, Andrew Haines, Mounia Lalmas

There are many circumstances however where it is important to understand (i) why a model outputs a certain prediction on a given instance, (ii) which adjustable features of that instance should be modified, and finally (iii) how to alter such a prediction when the mutated instance is input back to the model.

Feature Engineering

Scalable Semantic Matching of Queries to Ads in Sponsored Search Advertising

no code implementations7 Jul 2016 Mihajlo Grbovic, Nemanja Djuric, Vladan Radosavljevic, Fabrizio Silvestri, Ricardo Baeza-Yates, Andrew Feng, Erik Ordentlich, Lee Yang, Gavin Owens

For this reason search engines often provide a service of advanced matching, which automatically finds additional relevant queries for advertisers to bid on.

Neighborhood Sensitive Mapping for Zero-Shot Classification using Independently Learned Semantic Embeddings

no code implementations26 May 2016 Gaurav Singh, Fabrizio Silvestri, John Shawe-Taylor

In a traditional setting, classifiers are trained to approximate a target function $f:X \rightarrow Y$ where at least a sample for each $y \in Y$ is presented to the training algorithm.

General Classification Zero-Shot Learning

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