Definable groups
definable C^r groups
o-minimal
definable C^r fiber bundles
definable G sets
definable slices
proper
definable G imbeddings
Let M=(R,+,・,<,...) be an o-minimal expansion of the standard structure R=(R,+,・,<) of the field of real numbers. Let G be a definable C^r group and H a definable C^r subgroup of G. We prove that if M. admits the C^ω (resp. C^∞) cell decomposition or 0 ≤ r < ∞, then the orbit map π : G → G