EntityQ852973· pop 42· linked from 548 articlesEuler characteristicSign in to savetopological invariant in mathematicsConnectionshomotopyEntityCW complexEntitypolyhedronEntityparityEntityfaceEntityplanar graphEntityconnected spaceEntityhomologyEntitymathematicsEntityRené DescartesEntityLeonhard EulerEntityGreek alphabetEntityInternational Standard Book NumberEntitynatural numberEntitycircleEntitycomplex numberEntitytopologyEntityrational numberEntitysetEntitysphereEntityCategoriesAlgebraic topologyLeonhard EulerPolyhedral combinatoricsTopological graph theory