  In this note we obtain semiclassical resolvent estimates for non-trapping
long range perturbations of the Laplacian on asymptotically Euclidean
manifolds. Our proof is based on a positive commutator argument which differs
from Mourre-type estimates by making the commutant also positive. The resolvent
estimates, including the weighting of the Sobolev spaces in the estimates, are
an immediate consequence.
