com12

Theorem. Swap antecedents.

Description:

Theorem *2.04 of Principia Mathematica, p.100; pm2.04 in set.mm.

Arguments:

(pr), (pr), (pr),

Assertions:

((())(()))

Proof:

Hyp	Ref	Line	Expr
	ax2	1	((())(()()))
	ax1	2	(())
1, 2	rpi32	3	((())(()))