← Search

Vassilis N. Ioannidis

16 accepted papers

2025

BYOKG-RAG: Multi-Strategy Graph Retrieval for Knowledge Graph Question Answering

EMNLP 2025

Knowledge graph question answering (KGQA) presents significant challenges due to the structural and semantic variations across input graphs. Existing works rely on Large Language Model (LLM) agents for graph traversal and retrieval; an approach that is sensitive to traversal initialization, as it is

2025

GRIL: Knowledge Graph Retrieval-Integrated Learning with Large Language Models

EMNLP 2025

Retrieval-Augmented Generation (RAG) has significantly mitigated the hallucinations of Large Language Models (LLMs) by grounding the generation with external knowledge. Recent extensions of RAG to graph-based retrieval offer a promising direction, leveraging the structural knowledge for multi-hop re

Cited by 0SourcePDFScholar
2025

HybGRAG: Hybrid Retrieval-Augmented Generation on Textual and Relational Knowledge Bases

ACL 2025long

Given a semi-structured knowledge base (SKB), where text documents are interconnected by relations, how can we effectively retrieve relevant information to answer user questions?Retrieval-Augmented Generation (RAG) retrieves documents to assist large language models (LLMs) in question answering; whi…

2025

Spectro-Riemannian Graph Neural Networks

ICLR 2025poster

Can integrating spectral and curvature signals unlock new potential in graph representation learning? Non-Euclidean geometries, particularly Riemannian manifolds such as hyperbolic (negative curvature) and spherical (positive curvature), offer powerful inductive biases for embedding complex graph st…

Cited by 0SourcePDFScholar
2024

AvaTaR: Optimizing LLM Agents for Tool Usage via Contrastive Reasoning

NeurIPS 2024poster

Large language model (LLM) agents have demonstrated impressive capabilities in utilizing external tools and knowledge to boost accuracy and reduce hallucinations. However, developing prompting techniques that enable LLM agents to effectively use these tools and knowledge remains a heuristic and labo…

2024

BioBridge: Bridging Biomedical Foundation Models via Knowledge Graphs

ICLR 2024poster

Foundation models (FMs) learn from large volumes of unlabeled data to demonstrate superior performance across a wide range of tasks. However, FMs developed for biomedical domains have largely remained unimodal, i.e., independently trained and used for tasks on protein sequences alone, small molecule…

2024

NetInfoF Framework: Measuring and Exploiting Network Usable Information

ICLR 2024spotlight

Given a node-attributed graph, and a graph task (link prediction or node classification), can we tell if a graph neural network (GNN) will perform well? More specifically, do the graph structure and the node features carry enough usable information for the task? Our goals are (1) to develop a fast t…

2024

STaRK: Benchmarking LLM Retrieval on Textual and Relational Knowledge Bases

NeurIPS 2024poster

Answering real-world complex queries, such as complex product search, often requires accurate retrieval from semi-structured knowledge bases that involve blend of unstructured (e.g., textual descriptions of products) and structured (e.g., entity relations of products) information. However, many prev…

2023

Predicting Cellular Responses with Variational Causal Inference and Refined Relational Information

ICLR 2023poster

Predicting the responses of a cell under perturbations may bring important benefits to drug discovery and personalized therapeutics. In this work, we propose a novel graph variational Bayesian causal inference framework to predict a cell's gene expressions under counterfactual perturbations (perturb…

2022

Does your graph need a confidence boost? Convergent boosted smoothing on graphs with tabular node features

ICLR 2022spotlight

Many practical modeling tasks require making predictions using tabular data composed of heterogeneous feature types (e.g., text-based, categorical, continuous, etc.). In this setting boosted decision trees and related ensembling techniques generally dominate real-world applications involving iid tr…

2022

TempoQR: Temporal Question Reasoning over Knowledge Graphs

AAAI 2022technical

Knowledge Graph Question Answering (KGQA) involves retrieving facts from a Knowledge Graph (KG) using natural language queries. A KG is a curated set of facts consisting of entities linked by relations. Certain facts include also temporal information forming a Temporal KG (TKG). Although many natura…

2021

Unveiling Anomalous Nodes Via Random Sampling and Consensus on Graphs

ICASSP 2021accepted

The present paper develops a graph-based sampling and consensus (GraphSAC) approach to effectively detect anomalous nodes in large-scale graphs. GraphSAC randomly draws sub-sets of nodes, and relies on graph-aware criteria to judiciously filter out sets contaminated by anomalous nodes, before employ…

Cited by 8SourceScholar
2020

Semi-Supervised Learning of Processes Over Multi-Relational Graphs

ICASSP 2020accepted

Semi-supervised learning (SSL) of dynamic processes over graphs is encountered in several applications of network science. Most of the existing approaches are unable to handle graphs with multiple relations, which arise in various real-world networks. This work deals with SSL of dynamic processes ov…

Cited by 0SourceScholar
2019

A Recurrent Graph Neural Network for Multi-relational Data

ICASSP 2019accepted

The era of "data deluge" has sparked the interest in graph-based learning methods in a number of disciplines such as sociology, biology, neuroscience, or engineering. In this paper, we introduce a graph recurrent neural network (GRNN) for scalable semi-supervised learning from multi-relational data.…

Cited by 0SourceScholar