Representation embeddings and the second Brauer-Thrall conjecture

We prove that over an algebraically closed field there is a representation embedding from the category of classical Kronecker-modules without the simple injective into the category of finite-dimensional modules over any representation-infinite finite-dimensional algebra. We also sharpen some known results on representation embeddings, we simplify some proofs and we construct a simultaneous orthogonal embedding for an infinite family of module categories. In the last section the minimal classes of representation-infinite algebras are determined. The result depends on the characteristic.