Presentation and central extensions of mapping class groups

We give a presentation of the mapping class group $\mathcal {M}$ of a (possibly bounded) surface, considering either all twists or just non-separating twists as generators. We also study certain central extensions of $\mathcal {M}$. One of them plays a key role in studying TQFT functors, namely the mapping class group of a $p_1$-structure surface. We give a presentation of this extension.