Name Inasa Nakamura Kyoto University Session Jan 10 16:00~16:20 E11-101 Unknotting numbers of torus-covering knots A torus-covering knot is an oriented surface knot which is in the form of a covering over the standard torus. The unknotting number of an oriented surface knot $F$ is the minimal number of disjoint 1-handles necessary to deform $F$ to an unknotted surface knot by 1-handle surgery. In this talk we study unknotting numbers of torus-covering knots. In particular, we give examples of torus-covering knots with the unknotting number exactly $n$. 101-1-10/2-I_Nakamura_2012-0110.pdf