#### Abstract

While uniication in the simple theory of types (a.k.a. higher-order logic) is undecidable, we show that uni-cation in the pure ramiied theory of types with integer levels is decidable. Since pure ramiied type theory is not very expressive, we examine the impure case, which has an undecidable uniication problem even at order 2. However, the decidability… (More)