English
If a HasFPowerSeriesWithinOnBall f pf s (u x) r holds, then HasFPowerSeriesWithinOnBall (f ∘ u) (pf.compContinuousLinearMap u) (u⁻¹' s) x (r / ‖u‖)
Русский
Если существует разложение в шаре для f вокруг u x, то для композиции f∘u существует разложение вокруг x с нормой u, радиус делится на ‖u‖.
LaTeX
$$HasFPowerSeriesWithinOnBall f pf s (ContinuousLinearMap.funLike.coe u x) r → HasFPowerSeriesWithinOnBall (f ∘ u) (pf.compContinuousLinearMap u) (Set.preimage (ContinuousLinearMap.funLike.coe u) s) x (r / ‖u‖ₑ)$$
Lean4
theorem compContinuousLinearMap (hf : HasFPowerSeriesOnBall f pf (u x) r) :
HasFPowerSeriesOnBall (f ∘ u) (pf.compContinuousLinearMap u) x (r / ‖u‖ₑ) :=
by
rw [← hasFPowerSeriesWithinOnBall_univ] at hf ⊢
exact hf.compContinuousLinearMap