Theorem 19.28vv 45124

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 2025	. . 3 ⊢ (∀𝑦(𝜓 ∧ 𝜑) ↔ (𝜓 ∧ ∀𝑦𝜑))
2	1	albii 1848	. 2 ⊢ (∀𝑥∀𝑦(𝜓 ∧ 𝜑) ↔ ∀𝑥(𝜓 ∧ ∀𝑦𝜑))
3		19.28v 2025	. 2 ⊢ (∀𝑥(𝜓 ∧ ∀𝑦𝜑) ↔ (𝜓 ∧ ∀𝑥∀𝑦𝜑))
4	2, 3	bitri 278	1 ⊢ (∀𝑥∀𝑦(𝜓 ∧ 𝜑) ↔ (𝜓 ∧ ∀𝑥∀𝑦𝜑))

This proof depends on syntax axioms:   ↔ wb 209   ∧ wa 400  ∀wal 1567

This proof depends on axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1824  ax-4 1838  ax-5 1939  ax-6 1996

This proof depends on definitions:  df-bi 210  df-an 401  df-ex 1809

This theorem is used by: (None)