CheckThat! at CLEF 2019: Automatic identification and verification of claims

We introduce the second edition of the CheckThat! Lab, part of the 2019 Cross-Language Evaluation Forum (CLEF). CheckThat! proposes two complementary tasks. Task 1: predict which claims in a political debate should be prioritized for fact-checking. Task 2: rank Web-retrieved pages against a check-worthy claim based on their usefulness for fact-checking, extract useful passages from those pages, and then use them all to decide whether the claim is factually true or false. Checkthat! provides a full evaluation framework, consisting of data in English (derived from fact-checking sources) and Arabic (gathered and annotated from scratch) and evaluation based on mean average precision (MAP) for ranking and F 1 for classification tasks.