Description: Alternate proof of darii , shorter but using more axioms. This shows
how the use of spi may shorten some proofs of the Aristotelian
syllogisms, even though this adds axiom dependencies. Note that spi is the inference associated with sp , which corresponds to the axiom
(T) of modal logic. (Contributed by David A. Wheeler, 27-Aug-2016)
Added precisions on axiom usage. (Revised by BJ, 27-Sep-2022)(Proof modification is discouraged.)(New usage is discouraged.)