Annulus-quotient model of Dehn filling
= Annulus-quotient model of Dehn filling
Let two parallel curves $\beta_1,\beta_2$ cut a torus boundary into annuli $A_1,A_2$, and let a slope $\alpha$ meet each $\beta_i$ once. Identifying $A_1$ with $A_2$ by an orientation-reversing map fixing their boundary and matching the two arcs of $\alpha$ produces the same manifold as the Dehn filling $X(\alpha)$. A collar of the boundary turns the quotient region into the solid torus attached by the filling.