EntityQ315296· pop 22· linked from 82 articlesErlangen programSign in to saveresearch program on the symmetries of geometryConnectionsEuclidean geometryEntitynon-Euclidean geometryEntitygroupoidEntityCharles EhresmannEntityphysicsEntitygeometryEntityEuclidEntityInternational Standard Book NumberEntitycircleEntitycomplex numberEntityangleEntitytopologyEntitydigital object identifierEntitysymmetryEntityJean PiagetEntitymathematical logicEntitygroupEntitydimensionEntitygroup theoryEntityconic sectionEntityCategoriesClassical geometryErlangenGroup theoryHomogeneous spacesSymmetry