Seven colors are required to color the surface of one of these entities, and the volume of one of these entities is equal to 2 pi squared times outer radius times inner radius squared.
Lawson's conjecture states that one of these objects named for Clifford is the only one that is minimally embedded in S-3. The rank of a compact Lie group is equal to the dimension of the maximal one of these entities in G. The n-dimensional one of these entities is defined by finding the product space of n circles. Seven colors are required to color the surface of one of these entities, and the volume of one of these entities is equal to 2 pi squared times outer radius times inner radius squared. For 10 points, name this surface that is famously homotopic to a coffee cup, since both have a single hole, a surface of revolution generated by rotating a circle through an axis not intersecting and co-planar with it.
Lawson's conjecture states that one of these objects named for Clifford is the only one that is minimally embedded in S-3.
torus [prompt on "donut"]