Whether they are hand written or generated by an automated prover, long proofs may be difficult to understand and follow.
The main reason for this is that at some point in the proof formulae that occur lines, paragraphs or even pages before, are
used. The proof presentation method proposed here tries to overcome this by showing, in each proof step, exactly the formulae
that are relevant for the particular proof step. We describe the implementation of this method in the frame of the Theorema system.
partially supported by the RISC PhD scholarship program of the government of Upper Austria and by the FWF (Austrian Science
Foundation) SFB project P1302