diff --git a/sections/preface.tex b/sections/preface.tex
@@ -19,12 +19,14 @@ relevant results.
Hence some results are left unproved. Nevertheless, we include numerous
references throughout the text to other materials where the reader can find
complete proofs. We will assume basic knowledge of abstract algebra. In
-particular, we assume that the reader is familiarized with multi-linear algebra
-and the theory of modules over a ring. Understanding some examples in the
-introductory chapter requires basic knowledge of differential and algebraic
-geometry, as well as rings of differential operators, but these examples are
-not necessary to the comprehension of the following chapters. Additional topics
-will be covered in the notes as needed.
+particular, we assume that the reader is familiarized with multi-linear
+algebra, the theory of modules over an algebra and exact sequences. We also
+assume familiarity with the language of categories, functors and adjunctions.
+Understanding some examples in the introductory chapter requires basic
+knowledge of differential and algebraic geometry, as well as rings of
+differential operators, but these examples are not necessary to the
+comprehension of the following chapters. Additional topics will be covered in
+the notes as needed.
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