NLytics at CheckThat! 2021: Detecting previously fact-checked claims by measuring semantic similarity

The following system description presents our approach to the detection of previously fact-checked claims. Given a claim originating from a tweet or a political debate, we specified the similarity to a collection of previously fact-checked claims. In line with the origin of the claims, the collection of previously fact-checked claims is composed of tweets and political debates respectively. The given task has been framed as a sequence similarity problem. Relevance scoring is based on semantic similarity. Similarity is calculated by distance metrics on representation vectors at paragraph level.