Zhang, X., Bussche, J.V. den, Wang, K., Zhang, H., Yang, X. and Feng, Z. 2020. On the Expressivity of ASK Queries in SPARQL. Proceedings of the AAAI Conference on Artificial Intelligence. 34, 03 (Apr. 2020), 3057-3064. DOI:https://doi.org/10.1609/aaai.v34i03.5700.