Theorem albi 1820

Description: Theorem 19.15 of [Margaris] p. 90. (Contributed by NM, 24-Jan-1993.)

Assertion

Ref	Expression
albi	⊢ (∀𝑥(𝜑 ↔ 𝜓) → (∀𝑥𝜑 ↔ ∀𝑥𝜓))

Proof of Theorem albi

Step	Hyp	Ref	Expression
1		biimp 215	. . 3 ⊢ ((𝜑 ↔ 𝜓) → (𝜑 → 𝜓))
2	1	al2imi 1817	. 2 ⊢ (∀𝑥(𝜑 ↔ 𝜓) → (∀𝑥𝜑 → ∀𝑥𝜓))
3		biimpr 220	. . 3 ⊢ ((𝜑 ↔ 𝜓) → (𝜓 → 𝜑))
4	3	al2imi 1817	. 2 ⊢ (∀𝑥(𝜑 ↔ 𝜓) → (∀𝑥𝜓 → ∀𝑥𝜑))
5	2, 4	impbid 212	1 ⊢ (∀𝑥(𝜑 ↔ 𝜓) → (∀𝑥𝜑 ↔ ∀𝑥𝜓))

Syntax hints:   → wi 4   ↔ wb 206  ∀wal 1540

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1797  ax-4 1811

This theorem depends on definitions:  df-bi 207

This theorem is referenced by:  albii  1821  nfbiit  1853  albidh  1868  19.16  2233  19.17  2234  equvel  2461  eqeq1d  2739  raleqbidvvOLD  3307  rmoeq1  3383  elabgt  3628  ralss  4010  intmin4  4934  dfiin2g  4988  eunex  5337  bj-2albi  36839  bj-hbxfrbi  36859  bj-pm11.53vw  37004  bj-sblem  37086  wl-aleq  37784  wl-sb8ft  37799  2albi  44728  ralbidar  44794  trsbcVD  45226  sbcssgVD  45232  ichal  47820