Axiom ax-11 2150

Description: Axiom of Quantifier Commutation. This axiom says universal quantifiers can be swapped. Axiom scheme C6' in [Megill] p. 448 (p. 16 of the preprint). Also appears as Lemma 12 of [Monk2] p. 109 and Axiom C5-3 of [Monk2] p. 113. This axiom scheme is logically redundant (see ax11w 2124) but is used as an auxiliary axiom scheme to achieve metalogical completeness. (Contributed by NM, 12-Mar-1993.)

Assertion

Ref	Expression
ax-11	⊢ (∀𝑥∀𝑦𝜑 → ∀𝑦∀𝑥𝜑)

Detailed syntax breakdown of Axiom ax-11

Step	Hyp	Ref	Expression
1		wph	. . . 4 wff 𝜑
2		vy	. . . 4 setvar 𝑦
3	1, 2	wal 1599	. . 3 wff ∀𝑦𝜑
4		vx	. . 3 setvar 𝑥
5	3, 4	wal 1599	. 2 wff ∀𝑥∀𝑦𝜑
6	1, 4	wal 1599	. . 3 wff ∀𝑥𝜑
7	6, 2	wal 1599	. 2 wff ∀𝑦∀𝑥𝜑
8	5, 7	wi 4	1 wff (∀𝑥∀𝑦𝜑 → ∀𝑦∀𝑥𝜑)

This axiom is referenced by:  alcoms  2151  alcom  2152  hbal  2160  hbald  2161  nfald  2304  hbae  2397  hbaltg  32301  bj-hbalt  33260  hbae-o  35057  axc711  35068  axc5c711  35072  ax12indalem  35099  ax12inda2ALT  35100  pm11.71  39553  axc5c4c711  39557  axc11next  39562  hbalg  39715  hbalgVD  40074  hbexgVD  40075