Algebraic varieties named for this shape are subject to the orbit–cone correspondence and can be constructed from fans. For knots named for this shape, “x-to-the-p equals y-to-the-q” is a relation of the knot group. “R-squared” quotient “Z-squared” is isomorphic to this surface, (10[1])which has “Z-cross-Z” (-5[1])as its fundamental group. This surface can be obtained by gluing each pair of opposite edges (-5[2])of the unit square (-5[2])in the (10[1])same direction. (-5[1])This orientable surface with Euler characteristic zero (-5[1])is the Cartesian product of two circles. Depending on orientation, either a Klein bottle (-5[1])or this genus-one surface (-5[1])is formed by joining the circular (-5[1])ends of a cylinder. For 10 points, the surface of a coffee cup is topologically equivalent to what single-holed surface (10[1])shaped like a doughnut? ■END■ (10[7]0[2])