@InProceedings{lohrey:LIPIcs.STACS.2021.51,
  author =	{Lohrey, Markus},
  title =	{{Subgroup Membership in GL(2,Z)}},
  booktitle =	{38th International Symposium on Theoretical Aspects of Computer Science (STACS 2021)},
  pages =	{51:1--51:17},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-180-1},
  ISSN =	{1868-8969},
  year =	{2021},
  volume =	{187},
  editor =	{Bl\"{a}ser, Markus and Monmege, Benjamin},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.STACS.2021.51},
  URN =		{urn:nbn:de:0030-drops-136961},
  doi =		{10.4230/LIPIcs.STACS.2021.51},
  annote =	{Keywords: free groups, virtually free groups, subgroup membership, matrix groups}
}