Limiting Weak-Type Behaviors for Certain Classical Operators in Harmonic Analysis

This paper explores the limiting weak-type behaviors of certain classical operators in harmonic analysis including maximal operators, singular and fractional integral operators and maximal truncated singular integrals as well as the general convolution operators with weak-type Young’s inequalities. Some optimal limiting weak-type behaviors are given, which essentially improve and extend the previous results. As applications, several characterizations on the weak-type endpoint boundedness for fractional integral operators and maximal operators with homogeneous kernels, and the weak-type Young’s inequality for the general convolution operator are also obtained.