Theorem pm11.07

Description: Axiom *11.07 in WhiteheadRussell p. 159. The original reads: *11.07 "Whatever possible argument x may be, ph ( x , y ) is true whatever possible argument y may be" implies the corresponding statement with x and y interchanged except in " ph ( x , y ) ". Under our formalism this appears to correspond to idi and not to sbcom4 as earlier thought. See https://groups.google.com/g/metamath/c/iS0fOvSemC8/m/M1zTH8wxCAAJ . (Contributed by BJ, 16-Sep-2018) (New usage is discouraged.)

	Ref	Expression
Hypothesis	pm11.07.1	$$⊢\phi$$
Assertion	pm11.07	$$⊢\phi$$

Proof

Step	Hyp	Ref	Expression
1		pm11.07.1	$$⊢\phi$$