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CLASSICAL FIRST-ORDER LOGIC WITH EQUALITY
Predicate calculus with equality: Tarski's system S2 (1 rule, 6 schemes)
Axiom scheme ax-4 (Quantified Implication)
19.40-2
Metamath Proof Explorer
Description: Theorem *11.42 in WhiteheadRussell p. 163. Theorem 19.40 of Margaris
p. 90 with two quantifiers. (Contributed by Andrew Salmon , 24-May-2011)
Ref
Expression
Assertion
19.40-2
⊢ ∃ x ∃ y φ ∧ ψ → ∃ x ∃ y φ ∧ ∃ x ∃ y ψ
Proof
Step
Hyp
Ref
Expression
1
19.40
⊢ ∃ y φ ∧ ψ → ∃ y φ ∧ ∃ y ψ
2
1
eximi
⊢ ∃ x ∃ y φ ∧ ψ → ∃ x ∃ y φ ∧ ∃ y ψ
3
19.40
⊢ ∃ x ∃ y φ ∧ ∃ y ψ → ∃ x ∃ y φ ∧ ∃ x ∃ y ψ
4
2 3
syl
⊢ ∃ x ∃ y φ ∧ ψ → ∃ x ∃ y φ ∧ ∃ x ∃ y ψ