Question Answering Over Linked Data: What is Difficult to Answer? What Affects the F scores?
Abstract: We present a fine-grained analysis of the Question Answering over Linked Data (QALD-6) challenge. We divide the QALD-6 questions into 8 main categories and compare state-of-the-art questions answering (QA) systems over Linked Data against the individual categories. We show the difficulty (in terms of overall F scores of the QA systems) of each category. We show the effect of various natural language and SPARQL features such as the number of triple patterns, number of keywords, the answer size, the type of answers, the effect of aggregate functions, and the SPARQL query forms on the overall F scores of the QA systems.