We develop the necessary tools, including a notion of logarithmic derivative
for curves in homogeneous spaces, for deriving a general class of equations
including Euler-Poincar\'e equations on Lie groups and homogeneous spaces.
Orbit invariants play an important role in this context and we use these
invariants to prove global existence and uniqueness results for a class of PDE.
This class includes Euler-Poincar\'e equations that have not yet been
considered in the literature as well as integrable equations like Camassa-Holm,
Degasperis-Procesi, $\mu$CH and $\mu$DP equations, and the geodesi
We generalize the prequantization central extension of a group of
diffeomorphisms preserving a closed 2--form $\omega$ ($\omega$--invariant
diffeomorphisms) to an abelian extension of a group of diffeomorphisms
preserving a closed vector valued 2--form $\omega$ up to a linear isomorphism
($\omega$--equivariant diffeomorphisms). Every abelian extension of a simply
connected Lie group can be obtained as the pull-back of such a prequantization
abelian extension.