EntityQ48999401· pop 6· linked from 9 articlesOberwolfach problemSign in to saveUnsolved problem of discrete mathematicsConnectionsmathematicsEntityInternational Standard Book NumberEntitynatural numberEntitydigital object identifierEntitygraph theoryEntitybibcodeEntityQ118398EntityCambridge University PressEntitycomplete graphEntitylist of unsolved problems in mathematicsEntityregular graphEntityhypergraphEntitycycle graphEntityMathematical ReviewsEntityMathematical Research Institute of OberwolfachEntityopen problemEntityDaniela KühnEntityGerhard RingelEntityKirkman's schoolgirl problemEntityHanfried LenzEntityCategoriesMathematical problemsUnsolved problems in graph theory