  The asymptotic symmetry group of three-dimensional (anti) de Sitter space is
the two dimensional conformal group with central charge $c=3\ell/2G$. Usually
the asymptotic charge algebra is derived using the symplectic structure of the
bulk Einstein equations. Here, we derive the asymptotic charge algebra by a
different route. First, we formulate the dynamics of the boundary as a
1+1-dimensional dynamical system. Then we realize the boundary equations of
motion as a Hamiltonian system on the dual Lie algebra, $\mathfrak{g}^*$, of
the two-dimensional conformal group. Finally, we use the Lie-Poisson bracket on
$\mathfrak{g}^*$ to compute the asymptotic charge algebra. This streamlines the
derivation of the asymptotic charge algebra because the Lie-Poisson bracket on
the boundary is significantly simpler than the symplectic structure derived
from the bulk Einstein equations. It also clarifies the analogy between the
infinite dimensional symmetries of gravity and fluid dynamics.
