 Hypothetical syllogisms consisting of a conditional and a disjunctive premise are second, in terms of complexity, only to the combination of conditionals and categoricals (type 4 below). The proof of the productive moods, in addition to the standard methods seen above, often involves turning a conditional premise into a disjunctive premise or vice versa (the analysis of these inferential relations occupies Avicenna in Qiyās VII.1–2, but he uses them freely throughout Qiyās VI, before explicitly discussing them in the subsequent treatise). Similarly, after showing that a given premise pair yields a hypothetical conclusion of a certain kind, Avicenna often shows that it also yields a hypothetical conclusion of the other kind, whether logically equivalent or simply implied by the former.