“…However, as other intuitionistic theorem provers are written in different languages, are run on different machines and (in most cases) deal with firstorder formulae, comparison is hard. An (incomplete) list of other intuitionistic theorem provers is: [2], [4], [8], [11], [12], [13], [14]. Of the two calculi given here, the one with the smallest history and the least checking (the Swiss one) can become inefficient (see example 27.)…”