Description:
<p>In this paper, we survey some multiplier theorems and their applications to estimates for wave equation in Hardy spaces Hp(ℝn). We also prove Hp boundedness for Calderón-Zygmund operators of type σ which can be considered as a generalization of classical singular integral operators. Using these results, we discuss some recent progress in Hp regularity properties of the solving operators for hyperbolic equations.</p>