The CLEF-2026 CheckThat! Lab: Advancing Multilingual Fact-Checking

TL;DR

The CLEF-2026 CheckThat! Lab focuses on developing multilingual fact-checking technologies across various tasks, including source retrieval, claim verification, and article generation, to combat disinformation in online communication.

Contribution

It introduces new tasks for the verification pipeline, including source retrieval, reasoning-based fact-checking, and article generation, expanding previous editions' scope.

Findings

Enhanced source retrieval for scientific claims

Improved fact-checking of numerical and temporal claims

Development of full-fact-checking article generation

Abstract

The CheckThat! lab aims to advance the development of innovative technologies combating disinformation and manipulation efforts in online communication across a multitude of languages and platforms. While in early editions the focus has been on core tasks of the verification pipeline (check-worthiness, evidence retrieval, and verification), in the past three editions, the lab added additional tasks linked to the verification process. In this year's edition, the verification pipeline is at the center again with the following tasks: Task 1 on source retrieval for scientific web claims (a follow-up of the 2025 edition), Task 2 on fact-checking numerical and temporal claims, which adds a reasoning component to the 2025 edition, and Task 3, which expands the verification pipeline with generation of full-fact-checking articles. These tasks represent challenging classification and retrieval problems as well as generation challenges at the document and span level, including multilingual settings.