EntityQ875399· pop 30· linked from 243 articlesboundarySign in to savedividing line between two areas or sets of points in a topological space; difference between the closure and the interiorConnectionsmanifoldEntityintervalEntitycomplementEntitydense setEntityinteriorEntitymathematicsEntityInternational Standard Book NumberEntitytopologyEntityrational numberEntitysurfaceEntitysubsetEntitycontinuous functionEntitymetric spaceEntitytopological spaceEntityVenn diagramEntitylist of mathematical symbolsEntitynumber lineEntityMandelbrot setEntityalgebraic topologyEntityPoincaré conjectureEntityCategoriesGeneral topology