Mahmoud Fathallah


2025

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AlexUNLP-FMT at ClimateCheck Shared Task: Hybrid Retrieval with Adaptive Similarity Graph-based Reranking for Climate-related Social Media Claims Fact Checking
Mahmoud Fathallah | Nagwa El-Makky | Marwan Torki
Proceedings of the Fifth Workshop on Scholarly Document Processing (SDP 2025)

In this paper, we describe our work done in the ClimateCheck shared task at the Scholarly document processing (SDP) workshop, ACL 2025. We focused on subtask 1: Abstracts Retrieval. The task involved retrieving relevant paper abstracts from a large corpus to verify claims made on social media about climate change. We explored various retrieval and ranking techniques, including fine-tuning transformer-based dense retrievers, sparse retrieval methods, and reranking using cross-encoder models. Our final and best-performing system utilizes a hybrid retrieval approach combining BM25 sparse retrieval and a fine-tuned Stella model for dense retrieval, followed by an MSMARCO trained minilm cross-encoder model for ranking. We adapt an iterative graph-based re-ranking approach leveraging a document similarity graph built for the document corpus to dynamically update candidate pool for reranking. This system achieved a score of 0.415 on the final test set for subtask 1, securing 3rd place in the final leader board.