Theorem exintr 1614

Description: Introduce a conjunct in the scope of an existential quantifier. (Contributed by NM, 11-Aug-1993.)

Assertion

Ref	Expression
exintr	⊢ (∀x(φ → ψ) → (∃xφ → ∃x(φ ∧ ψ)))

Proof of Theorem exintr

Step	Hyp	Ref	Expression
1		exintrbi 1613	. 2 ⊢ (∀x(φ → ψ) → (∃xφ ↔ ∃x(φ ∧ ψ)))
2	1	biimpd 198	1 ⊢ (∀x(φ → ψ) → (∃xφ → ∃x(φ ∧ ψ)))

Syntax hints:   → wi 4   ∧ wa 358  ∀wal 1540  ∃wex 1541

This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-3 7  ax-mp 8  ax-gen 1546  ax-5 1557

This theorem depends on definitions:  df-bi 177  df-an 360  df-ex 1542

This theorem is referenced by:  ceqsex  2893  r19.2z  3639  pwpw0  3855  pwsnALT  3882