Heuristical Criteria in Refutational Theorem Proving

We hope to have convinced the reader by now, that the extra time spent on the calculations of the measures of the various rules is not wasted, but serves instead as the key factor in the reduction of the size of the search-space. It would seem however that there exists no index function γ, and no sorting strategy Sort, such that γ-Sort (or Sort-γ) be uniformly efficient in all cases. This is the main reason why the software SBR3 has opted for a lexicographic combination of more than one filtration-sorting, giving an appreciable overall efficiency.