Theorem 19.43 1621

Description: Theorem 19.43 of [Margaris] p. 90. (Contributed by NM, 5-Aug-1993.) (Proof shortened by Mario Carneiro, 2-Feb-2015.)

Assertion

Ref	Expression
19.43	⊢ (∃𝑥(𝜑 ∨ 𝜓) ↔ (∃𝑥𝜑 ∨ ∃𝑥𝜓))

Proof of Theorem 19.43

Step	Hyp	Ref	Expression
1		hbe1 1488	. . . 4 ⊢ (∃𝑥𝜑 → ∀𝑥∃𝑥𝜑)
2		hbe1 1488	. . . 4 ⊢ (∃𝑥𝜓 → ∀𝑥∃𝑥𝜓)
3	1, 2	hbor 1539	. . 3 ⊢ ((∃𝑥𝜑 ∨ ∃𝑥𝜓) → ∀𝑥(∃𝑥𝜑 ∨ ∃𝑥𝜓))
4		19.8a 1583	. . . 4 ⊢ (𝜑 → ∃𝑥𝜑)
5		19.8a 1583	. . . 4 ⊢ (𝜓 → ∃𝑥𝜓)
6	4, 5	orim12i 754	. . 3 ⊢ ((𝜑 ∨ 𝜓) → (∃𝑥𝜑 ∨ ∃𝑥𝜓))
7	3, 6	exlimih 1586	. 2 ⊢ (∃𝑥(𝜑 ∨ 𝜓) → (∃𝑥𝜑 ∨ ∃𝑥𝜓))
8		orc 707	. . . 4 ⊢ (𝜑 → (𝜑 ∨ 𝜓))
9	8	eximi 1593	. . 3 ⊢ (∃𝑥𝜑 → ∃𝑥(𝜑 ∨ 𝜓))
10		olc 706	. . . 4 ⊢ (𝜓 → (𝜑 ∨ 𝜓))
11	10	eximi 1593	. . 3 ⊢ (∃𝑥𝜓 → ∃𝑥(𝜑 ∨ 𝜓))
12	9, 11	jaoi 711	. 2 ⊢ ((∃𝑥𝜑 ∨ ∃𝑥𝜓) → ∃𝑥(𝜑 ∨ 𝜓))
13	7, 12	impbii 125	1 ⊢ (∃𝑥(𝜑 ∨ 𝜓) ↔ (∃𝑥𝜑 ∨ ∃𝑥𝜓))

Syntax hints:   ↔ wb 104   ∨ wo 703  ∃wex 1485

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-ia1 105  ax-ia2 106  ax-ia3 107  ax-io 704  ax-5 1440  ax-gen 1442  ax-ie1 1486  ax-ie2 1487  ax-4 1503  ax-ial 1527

This theorem depends on definitions:  df-bi 116

This theorem is referenced by:  19.44  1675  19.45  1676  19.34  1677  sborv  1883  r19.43  2628  rexun  3307  unipr  3810  uniun  3815  unopab  4068  dmun  4818  coundi  5112  coundir  5113