A space named for this mathematician is the simplest nontrivial fiber bundle of an interval over S1 (“S-one”); a quotient space description of that space is as a torus over the group action of the symmetric group on two letters. This mathematician names transformations of the complex plane with the form “az-plus-b over cz-plus-d,” as well as a function equal to zero for any number with a squared prime factor. Attaching the edges of an Euler characteristic-zero surface named for this mathematician (-5[1])to itself forms the real projective plane, (10[1])while joining two copies of that non-orientable surface along their boundaries (10[2])creates a (10[1])Klein bottle. For 10 points, twisting (10[1])a piece of paper and gluing its ends (10[1])together creates what (10[1])German mathematician’s one-sided “strip”? ■END■ (10[1])