Theorem 19.29r2 1908

Description: Variation of 19.29r 1907 with double quantification. (Contributed by NM, 3-Feb-2005.)

Assertion

Ref	Expression
19.29r2	⊢ ((∃𝑥∃𝑦𝜑 ∧ ∀𝑥∀𝑦𝜓) → ∃𝑥∃𝑦(𝜑 ∧ 𝜓))

Proof of Theorem 19.29r2

Step	Hyp	Ref	Expression
1		19.29r 1907	. 2 ⊢ ((∃𝑥∃𝑦𝜑 ∧ ∀𝑥∀𝑦𝜓) → ∃𝑥(∃𝑦𝜑 ∧ ∀𝑦𝜓))
2		19.29r 1907	. . 3 ⊢ ((∃𝑦𝜑 ∧ ∀𝑦𝜓) → ∃𝑦(𝜑 ∧ 𝜓))
3	2	eximi 1868	. 2 ⊢ (∃𝑥(∃𝑦𝜑 ∧ ∀𝑦𝜓) → ∃𝑥∃𝑦(𝜑 ∧ 𝜓))
4	1, 3	syl 18	1 ⊢ ((∃𝑥∃𝑦𝜑 ∧ ∀𝑥∀𝑦𝜓) → ∃𝑥∃𝑦(𝜑 ∧ 𝜓))

This proof depends on syntax axioms:   → wi 4   ∧ wa 401  ∀wal 1568  ∃wex 1812

This proof depends on axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1828  ax-4 1842

This proof depends on definitions:  df-bi 210  df-an 402  df-ex 1813

This theorem is used by:  funen1cnv  9035