  The Diproche system, an automated proof checker for natural language proofs
specifically adapted to the context of exercises for beginner's students
similar to the Naproche system by Koepke, Schr\"oder, Cramer and others, uses a
modification of an automated theorem prover which uses common formal fallacies
intead of sound deduction rules for mistake diagnosis. We briefly describe the
concept of such an `Anti-ATP' and explain the basic techniques used in its
implementation.
