EntityQ1443782· pop 5· linked from 13 articlesMoser spindleSign in to saveundirected unit-distance graph requiring four colorsConnectionsgraph coloringEntityInternational Standard Book NumberEntityrhombusEntitydigital object identifierEntityplaneEntitygraph theoryEntitygraphEntitybibcodeEntityQ118398Entityaxiom of choiceEntityMathWorldEntitycomplete graphEntityQ22908627EntitynodeEntityplanar graphEntityNP-completeEntityconvex hullEntityEric W. WeissteinEntityboolean satisfiability problemEntityRamsey theoryEntityCategoriesIndividual graphsPlanar graphs