The braid group $B_3$ in the framework of continued fractions

We use the classical interpretation of the braid group $B_3$ as a central extension of the modular group ${\text{PSL}}_2\left(\mathbb{Z}\right)$ to establish new and fundamental properties of $B_3$ using the theory of continued fractions. In particular, we give simple and natural linear time algorithms to solve the word and conjugacy problems in $B_3$. The algorithms introduced in this paper are easy to implement and are the most efficient algorithms in the literature to solve these problems in the braid group $B_3$.