ABSTRACT
In this chapter, we study obstructions to the existence of equivariant birational maps between varieties with semi-ample anticanonical divisors and varieties fibered into varieties of negative or zero Kodaira dimension. These obstructions are the most important global tools used in the proof of Theorem 1.4.1, which is the main result of this book. They will also be used in the proofs of Theorems 19.1.1, 19.1.3, and 19.1.4.
