We are concerned with Hardy and BMO spaces of operator-valued functions analytic in the unit disk of C. In the case of the Hardy space, we involve the atomic decomposition since the usual argument in the scalar setting is not suitable. Several properties (the Garsia-norm equivalent theorem, Carleson measure, and so on) of BMOA spaces are extended to the operator-valued setting. Then, the operat...

We prove a $$C^m$$ Lusin approximation theorem for horizontal curves in the Heisenberg group. This states that every absolutely continuous curve whose velocity is $$m-1$$ times $$L^1$$ differentiable almost everywhere coincides with except on set of small measure. Conversely, we show result no longer holds if differentiability replaced by approximate differentiability. shows our optimal and hig...