Theorem 2moexv 2622

Description: Double quantification with "at most one". (Contributed by NM, 3-Dec-2001.)

Assertion

Ref	Expression
2moexv	⊢ (∃*𝑥∃𝑦𝜑 → ∀𝑦∃*𝑥𝜑)

Distinct variable group:   𝑥,𝑦

Allowed substitution hints:   𝜑(𝑥,𝑦)

Proof of Theorem 2moexv

Step	Hyp	Ref	Expression
1		nfe1 2146	. . 3 ⊢ Ⅎ𝑦∃𝑦𝜑
2	1	nfmov 2553	. 2 ⊢ Ⅎ𝑦∃*𝑥∃𝑦𝜑
3		19.8a 2173	. . 3 ⊢ (𝜑 → ∃𝑦𝜑)
4	3	moimi 2538	. 2 ⊢ (∃*𝑥∃𝑦𝜑 → ∃*𝑥𝜑)
5	2, 4	alrimi 2205	1 ⊢ (∃*𝑥∃𝑦𝜑 → ∀𝑦∃*𝑥𝜑)

Syntax hints:   → wi 4  ∀wal 1538  ∃wex 1780  ∃*wmo 2531

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1796  ax-4 1810  ax-5 1912  ax-6 1970  ax-7 2010  ax-10 2136  ax-11 2153  ax-12 2170

This theorem depends on definitions:  df-bi 206  df-or 845  df-tru 1543  df-ex 1781  df-nf 1785  df-mo 2533

This theorem is referenced by:  2eu5  2650