European Journal of CombinatoricsVolume 31, Issue 4, May 2010, Pages 1196-1204Problem sectionAuthor links open overlay panelV. Alexandrov, H. Maehara, A.D. Milka, I.Kh. Sabitov, J.-M. Schlenker, B. Servatius, H. ServatiusShow moreShareCitehttps://doi.org/10.1016/j.ejc.2009.11.021Get rights and contentUnder an Elsevier user licenseopen archivePrevious article in issueNext article in issueRecommended articlesCited by (0)Copyright © 2009 Elsevier Ltd. All rights reserved.