Theoretical Computer ScienceVolume 410, Issue 20, 1 May 2009, Page 1915PrefaceAuthor links open overlay panelMika HirvensaloShow moreShareCitehttps://doi.org/10.1016/j.tcs.2009.01.019Get rights and contentUnder an Elsevier user licenseopen archivePrevious article in issueNext article in issueRecommended articlesCited by (0)Copyright © 2009 Elsevier B.V. All rights reserved.