@InProceedings{bova_et_al:LIPIcs.ICDT.2017.9,
  author =	{Bova, Simone and Chen, Hubie},
  title =	{{How Many Variables Are Needed to Express an Existential Positive Query?}},
  booktitle =	{20th International Conference on Database Theory (ICDT 2017)},
  pages =	{9:1--9:16},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-024-8},
  ISSN =	{1868-8969},
  year =	{2017},
  volume =	{68},
  editor =	{Benedikt, Michael and Orsi, Giorgio},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ICDT.2017.9},
  URN =		{urn:nbn:de:0030-drops-70545},
  doi =		{10.4230/LIPIcs.ICDT.2017.9},
  annote =	{Keywords: existential positive queries, finite-variable logics, first-order logic, query optimization}
}