Theorem 19.28vv 44410

Description: Theorem *11.47 in [WhiteheadRussell] p. 164. Theorem 19.28 of [Margaris] p. 90 with 2 quantifiers. (Contributed by Andrew Salmon, 24-May-2011.)

Assertion

Ref	Expression
19.28vv	⊢ (∀𝑥∀𝑦(𝜓 ∧ 𝜑) ↔ (𝜓 ∧ ∀𝑥∀𝑦𝜑))

Distinct variable groups:   𝜓,𝑥   𝜓,𝑦

Allowed substitution hints:   𝜑(𝑥,𝑦)

Proof of Theorem 19.28vv

Step	Hyp	Ref	Expression
1		19.28v 1989	. . 3 ⊢ (∀𝑦(𝜓 ∧ 𝜑) ↔ (𝜓 ∧ ∀𝑦𝜑))
2	1	albii 1818	. 2 ⊢ (∀𝑥∀𝑦(𝜓 ∧ 𝜑) ↔ ∀𝑥(𝜓 ∧ ∀𝑦𝜑))
3		19.28v 1989	. 2 ⊢ (∀𝑥(𝜓 ∧ ∀𝑦𝜑) ↔ (𝜓 ∧ ∀𝑥∀𝑦𝜑))
4	2, 3	bitri 275	1 ⊢ (∀𝑥∀𝑦(𝜓 ∧ 𝜑) ↔ (𝜓 ∧ ∀𝑥∀𝑦𝜑))

Syntax hints:   ↔ wb 206   ∧ wa 395  ∀wal 1537

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1794  ax-4 1808  ax-5 1909  ax-6 1966

This theorem depends on definitions:  df-bi 207  df-an 396  df-ex 1779

This theorem is referenced by: (None)