摘要：In this lecture, we will present the connection of QED constant with other conformal invariants of domains such as the QC reflection constant R(D). The Garnett-Yang conjecture and a counterexample will also be presented. We introduce several conformal invariants associated with a quasisymmetric homeomorphism of the unit circle (or real line). We will discuss how these invariants are related to each other and how they are related to the QED constant and reflection constant (introduced in the previous lectures). Topics will include some earlier results of Shen, Wu and Yang, as well as new results of Cheng-Yang on related problems.