EntityQ32918· pop 19· linked from 51 articlesthree utilities problemSign in to savemathematical problemConnectionsminor graphEntitystructural rigidityEntityInternational Standard Book NumberEntitydigital object identifierEntitybenzeneEntityplaneEntitygraph theoryEntitysurfaceEntitytorusEntityMöbius stripEntitygraphEntityJSTOREntityelectric lightEntitybibcodeEntitymugEntityMartin GardnerEntityalgebraic equationEntityKazimierz KuratowskiEntityEuler characteristicEntityMathWorldEntityCategoriesMathematical puzzlesTopological graph theoryUnsolvable puzzles