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Michalis Vazirgiannis

32 accepted papers

2025

Bias in the Mirror : Are LLMs opinions robust to their own adversarial attacks

ACL 2025long

Large language models (LLMs) inherit biases from their training data and alignment processes, influencing their responses in subtle ways. While many studies have examined these biases, little work has explored their robustness during interactions. In this paper, we introduce a novel approach where t…

Cited by 0SourcePDFScholar
2025

Graph Neural Network Generalization With Gaussian Mixture Model Based Augmentation

ICML 2025poster

Graph Neural Networks (GNNs) have shown great promise in tasks like node and graph classification, but they often struggle to generalize, particularly to unseen or out-of-distribution (OOD) data. These challenges are exacerbated when training data is limited in size or diversity. To address these is…

Cited by 0SourcePDFScholar
2025

LLM as a Broken Telephone: Iterative Generation Distorts Information

ACL 2025long

As large language models are increasingly responsible for online content, concerns arise about the impact of repeatedly processing their own outputs.Inspired by the “broken telephone” effect in chained human communication, this study investigates whether LLMs similarly distort information through it…

2025

Prediction via Shapley Value Regression

ICML 2025poster

Shapley values have several desirable, theoretically well-supported, properties for explaining black-box model predictions. Traditionally, Shapley values are computed post-hoc, leading to additional computational cost at inference time. To overcome this, a novel method, called ViaSHAP, is proposed,…

2025

Prot2Text-V2: Protein Function Prediction with Multimodal Contrastive Alignment

NeurIPS 2025poster

Predicting protein function from sequence is a central challenge in computational biology. While existing methods rely heavily on structured ontologies or similarity-based techniques, they often lack the flexibility to express structure-free functional descriptions and novel biological functions. In…

Cited by 0SourcecodeScholar
2025

Signed Graph Autoencoder for Explainable and Polarization-Aware Network Embeddings

AISTATS 2025poster

Autoencoders based on Graph Neural Networks (GNNs) have garnered significant attention in recent years for their ability to learn informative latent representations of complex topologies, such as graphs. Despite the prevalence of Graph Autoencoders, there has been limited focus on developing and eva…

Cited by 5SourceScholar
2024

A Simple and Yet Fairly Effective Defense for Graph Neural Networks

AAAI 2024technical

Graph Neural Networks (GNNs) have emerged as the dominant approach for machine learning on graph-structured data. However, concerns have arisen regarding the vulnerability of GNNs to small adversarial perturbations. Existing defense methods against such perturbations suffer from high time complexity…

2024

Bounding the Expected Robustness of Graph Neural Networks Subject to Node Feature Attacks

ICLR 2024poster

Graph Neural Networks (GNNs) have demonstrated state-of-the-art performance in various graph representation learning tasks. Recently, studies revealed their vulnerability to adversarial attacks. In this work, we theoretically define the concept of expected robustness in the context of attributed gra…

2024

GreekBART: The First Pretrained Greek Sequence-to-Sequence Model

COLING 2024main

The era of transfer learning has revolutionized the fields of Computer Vision and Natural Language Processing, bringing powerful pretrained models with exceptional performance across a variety of tasks. Specifically, Natural Language Processing tasks have been dominated by transformer-based language…

2024

If You Want to Be Robust, Be Wary of Initialization

NeurIPS 2024poster

Graph Neural Networks (GNNs) have demonstrated remarkable performance across a spectrum of graph-related tasks, however concerns persist regarding their vulnerability to adversarial perturbations. While prevailing defense strategies focus primarily on pre-processing techniques and adaptive message-p…

Cited by 1SourcePDFScholar
2024

Prot2Text: Multimodal Protein’s Function Generation with GNNs and Transformers

AAAI 2024technical

In recent years, significant progress has been made in the field of protein function prediction with the development of various machine-learning approaches. However, most existing methods formulate the task as a multi-classification problem, i.e. assigning predefined labels to proteins. In this work…

2024

The Curious Decline of Linguistic Diversity: Training Language Models on Synthetic Text

NAACL 2024findings

This study investigates the consequences of training language models on synthetic data generated by their predecessors, an increasingly prevalent practice given the prominence of powerful generative models. Diverging from the usual emphasis on performance metrics, we focus on the impact of this trai…

2023

Automatic Analysis of Substantiation in Scientific Peer Reviews

EMNLP 2023long findings

With the increasing amount of problematic peer reviews in top AI conferences, the community is urgently in need of automatic quality control measures. In this paper, we restrict our attention to substantiation --- one popular quality aspect indicating whether the claims in a review are sufficiently…

Cited by 0SourcecodeScholar
2023

FREDSum: A Dialogue Summarization Corpus for French Political Debates

EMNLP 2023long findings

Recent advances in deep learning, and especially the invention of encoder-decoder architectures, have significantly improved the performance of abstractive summarization systems. While the majority of research has focused on written documents, we have observed an increasing interest in the summariza…

Cited by 0SourcecodeScholar
2023

Graph Ordering Attention Networks

AAAI 2023technical

Graph Neural Networks (GNNs) have been successfully used in many problems involving graph-structured data, achieving state-of-the-art performance. GNNs typically employ a message-passing scheme, in which every node aggregates information from its neighbors using a permutation-invariant aggregation…

2023

Neural Architecture Search with Multimodal Fusion Methods for Diagnosing Dementia

ICASSP 2023accepted

Alzheimer’s dementia (AD) affects memory, thinking, and language, deteriorating person’s life. An early diagnosis is very important as it enables the person to receive medical help and ensure quality of life. Therefore, leveraging spontaneous speech in conjunction with machine learning methods for r…

Cited by 0SourceScholar
2023

Path Neural Networks: Expressive and Accurate Graph Neural Networks

ICML 2023poster

Graph neural networks (GNNs) have recently become the standard approach for learning with graph-structured data. Prior work has shed light into their potential, but also their limitations. Unfortunately, it was shown that standard GNNs are limited in their expressive power. These models are no more…

2023

Weisfeiler and Leman go Hyperbolic: Learning Distance Preserving Node Representations

AISTATS 2023poster

In recent years, graph neural networks (GNNs) have emerged as a promising tool for solving machine learning problems on graphs. Most GNNs are members of the family of message passing neural networks (MPNNs). There is a close connection between these models and the Weisfeiler-Leman (WL) test of isomo…

Cited by 11SourcePDFScholar
2022

DGraph: A Large-Scale Financial Dataset for Graph Anomaly Detection

NeurIPS 2022accept

Graph Anomaly Detection (GAD) has recently become a hot research spot due to its practicability and theoretical value. Since GAD emphasizes the application and the rarity of anomalous samples, enriching the varieties of its datasets is fundamental. Thus, this paper present DGraph, a real-world dynam…

Cited by 97SourcePDFScholar
2022

FrugalScore: Learning Cheaper, Lighter and Faster Evaluation Metrics for Automatic Text Generation

ACL 2022long

Fast and reliable evaluation metrics are key to R&D progress. While traditional natural language generation metrics are fast, they are not very reliable. Conversely, new metrics based on large pretrained language models are much more reliable, but require significant computational resources. In this…

2022

Node Feature Kernels Increase Graph Convolutional Network Robustness

AISTATS 2022poster

The robustness of the much used Graph Convolutional Networks (GCNs) to perturbations of their input is becoming a topic of increasing importance. In this paper the random GCN is introduced for which a random matrix theory analysis is possible. This analysis suggests that if the graph is sufficiently…

2022

Questioning the Validity of Summarization Datasets and Improving Their Factual Consistency

EMNLP 2022main

The topic of summarization evaluation has recently attracted a surge of attention due to the rapid development of abstractive summarization systems. However, the formulation of the task is rather ambiguous, neither the linguistic nor the natural language processing communities have succeeded in givi…

Cited by 9SourcePDFScholar
2021

BARThez: a Skilled Pretrained French Sequence-to-Sequence Model

EMNLP 2021main

Inductive transfer learning has taken the entire NLP field by storm, with models such as BERT and BART setting new state of the art on countless NLU tasks. However, most of the available models and research have been conducted for English. In this work, we introduce BARThez, the first large-scale pr…

2021

Ego-Based Entropy Measures for Structural Representations on Graphs

ICASSP 2021accepted

Machine learning on graph-structured data has attracted high research interest due to the emergence of Graph Neural Networks (GNNs). Most of the proposed GNNs are based on the node homophily, i.e neighboring nodes share similar characteristics. However, in many complex networks, nodes that lie to di…

Cited by 0SourceScholar
2021

Learning Parametrised Graph Shift Operators

ICLR 2021poster

In many domains data is currently represented as graphs and therefore, the graph representation of this data becomes increasingly important in machine learning. Network data is, implicitly or explicitly, always represented using a graph shift operator (GSO) with the most common choices being the adj…

2021

Transfer Graph Neural Networks for Pandemic Forecasting

AAAI 2021technical

The recent outbreak of COVID-19 has affected millions of individuals around the world and has posed a significant challenge to global healthcare. From the early days of the pandemic, it became clear that it is highly contagious and that human mobility contributes significantly to its spread. In this…

2020

Rep the Set: Neural Networks for Learning Set Representations

AISTATS 2020poster

In several domains, data objects can be decomposed into sets of simpler objects. It is then natural to represent each object as the set of its components or parts. Many conventional machine learning algorithms are unable to process this kind of representations, since sets may vary in cardinality and…

2020

Speaker-change Aware CRF for Dialogue Act Classification

COLING 2020main

Recent work in Dialogue Act (DA) classification approaches the task as a sequence labeling problem, using neural network models coupled with a Conditional Random Field (CRF) as the last layer. CRF models the conditional probability of the target DA label sequence given the input utterance sequence.…