Genera of knots in the complex projective plane
Abstract
Our goal is to systematically compute the ℂP2-genus of as many prime knots up to 8-crossings as possible. We obtain upper bounds on the ℂP2-genus via coherent band surgery. We obtain lower bounds by obstructing homological degrees of potential slice discs. The obstructions are pulled from a variety of sources in low-dimensional topology and adapted to ℂP2. There are 27 prime knots and distinct mirrors up to 7-crossings. We now know the ℂP2-genus of all of these knots. There are 64 prime knots and distinct mirrors up to 8-crossings. We now know the ℂP2-genus of all but 6 of these knots, where the ℂP2-genus was not determined explicitly, it was narrowed down to 2 possibilities. As a consequence of this work, we show an infinite family of knots such that the ℂP2-genus of each knot differs from that of its mirror.