Nonorientable surfaces bounded by knots: a geography problem

The nonorientable 4-genus is an invariant of knots which has been studied by many authors, including Gilmer and Livingston, Batson, and Ozsvath, Stipsicz, and Szabo. Given a nonorientable surface F subset of B-4 with partial derivative F = K subset of S-3 a knot, an analysis of the existing methods for bounding and computing the nonorientable 4-genus reveals relationships between the first Betti number beta(1) of F and the normal Euler class e of F. This relationship yields a geography problem: given a knot K, what is the set of realizable pairs (e(F), beta(1)(F)) where F subset of B-4 is a nonorientable surface bounded by K ? We explore this problem for families of torus knots. In addition, we use the Ozsvath-Szabo d-invariant of two-fold branched covers to give finer information on the geography problem. We present an infinite family of knots where this information provides an improvement upon the bound given by Ozsvath, Stipsicz, and Szabo using the Upsilon invariant.