8th challenge on question answering over linked data (QALD-8)

The QALD-8 challenge focused on the successful and long running multilingual QA task. For the first time, the participating teams were required to provide webservices of their systems to participate in the challenge, which will in turn support comparable research in the future. In this challenge, we also changed the underlying evaluation platform to account for the need for comparable experiments via webservices in contrast to former XML/JSON file submissions. This increased the entrance requirements for participating teams but ensures long term comparability of the system performance and a fair and open challenge. In the future, we will further simplify the participation process and offer leaderboards prior to the actual challenge to allow participants to see their performance beforehand. After feedback from the authors, we will likely add new key performance indicators for the capability of a system to know which questions it cannot answer and take confidence scores for answers into account. Moreover, we will remove most of the curve ball questions to reflect the original character of the QALD challenge, which provides a clean and linguistically challenging benchmark.