Take It All: Ensemble Retrieval for Multimodal Evidence Aggregation
Paper · 2026 · Max Upravitelev, Veronika Solopova, Premtim Sahitaj et al.
Summary
Fact-checking claims that pair text with images, such as miscaptioned photos or fabricated infographics, requires analyzing both modalities. Visual processing, however, makes systems slow and costly to run. The authors present ADA-AGGR, a pipeline for the FEVER 9 AVerImaTeC shared task. Instead of letting a model choose which retrieval tools to call, it runs every retriever on every claim, which avoids errors caused by poor tool selection. The pipeline combines:
- question generation with a VLM,
- hybrid text retrieval (BM25 candidates re-ranked by dense embeddings),
- image-only and image-plus-text retrieval based on ColPali embeddings.
The pooled results become a fixed set of ten evidence pieces, which feed a final verdict model. A variant built around Gemini 3 Pro placed second on both the dev and test leaderboards. The authors then ran extensive ablations with open-weight Qwen3 models to study the trade-off between accuracy and speed. Heavily shrinking the images given to the VLM cut average runtime by up to 6.28× with comparable scores. An LLM-based error analysis found that retrieved text drives most correct verdicts, while images help on average but can sometimes mislead.
Key points
- ADA-AGGR ranked 2nd of 17 teams on the AVerImaTeC dev leaderboard and 2nd on the test leaderboard (Gemini 3 Pro variant). The code is released on GitHub (XplaiNLP).
- Evidence budget: BM25 retrieves 1,000 candidates, and the top 5 after dense re-ranking are kept as text evidence. Two ColPali retrievers (image-only and multimodal) each return their top 3 images, which are merged and de-duplicated, for 10 evidence items in total.
- Open-weight configurations used Qwen3-VL 2B/8B (base and fine-tuned) for the generation steps and Qwen3 embedding models for text retrieval. Some smaller components lowered runtime without hurting results.
- Shrinking input images as much as eightfold made the pipeline up to 6.28× faster at similar quality. Even the fastest setup still needs about 75 seconds per claim.
- Suggested future work includes batching, vllm-style inference engines, smaller fine-tuned models, and further reduction of visual input. The system is meant as decision support for human fact-checkers, not a replacement.
Institutions
Fields, topics and concepts
📚 Shelves 7The field of science this work belongs to (OpenAlex fields).Computer Science · 16,667 worksArtificial Intelligence · 16,194 worksArts and Humanities · 16,039 worksLanguage and Linguistics · 15,891 worksComputer Vision and Pattern Recognition · 2,869 worksSocial Sciences · 1,772 worksSociology and Political Science · 577 works
🧭 Topics 2Research subjects and languages the work is about.Vision & language · 657 worksInformation retrieval & search · 473 works
Cite
Cite as Max Upravitelev, Veronika Solopova, Premtim Sahitaj, Ariana Sahitaj, Charlott Jakob, Sebastian Möller and Vera Schmitt. 2026. Take It All: Ensemble Retrieval for Multimodal Evidence Aggregation. Proceedings of the Ninth Fact Extraction and VERification Workshop (FEVER).
@inproceedings{upravitelev2026take,
title = {{Take It All: Ensemble Retrieval for Multimodal Evidence Aggregation}},
author = {Max Upravitelev, Veronika Solopova, Premtim Sahitaj, Ariana Sahitaj, Charlott Jakob, Sebastian Möller and Vera Schmitt},
booktitle = {Proceedings of the Ninth Fact Extraction and VERification Workshop (FEVER)},
year = {2026},
doi = {10.18653/v1/2026.fever-1.7},
url = {https://doi.org/10.18653/v1/2026.fever-1.7}
}References
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