19.12.2013 (Миша Слабодкин) The Depth of Resolution Proofs Alasdair Urquhart.

This paper investigates the depth of resolution proofs, that is to say,
the length of the longest path in the proof from an input clause to the
conclusion. An abstract characterization of the measure is given, as well
as a discussion of its relation to other measures of space complexity for
resolution proofs.