Name Yukari Funakoshi Nara Women's University Session Jan 10 16:50~17:10 E11-103 Pseudo-fiber surface and unknotting operation for fibered links. In [Ko], it is shown that the unknotting operations for unknotting number 1 fibered knots are realized by twists on fiber surfaces, which produce pre-fiber surfaces. In this talk, we propose a formulation generalizing the result for fibered links with unknotting numbers $\geq 2$, that is, ascending sequence of pseudo-fiber surfaces. Then we show that how it works for torus knots. [Ko] T. Kobayashi, Fibered links and unknotting operations, Osaka J. Math. 26 (1989), 699-742 103-1-10/YukariFunakoshi20120110.pdf