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ZF (ZERMELO-FRAENKEL) SET THEORY
ZF Set Theory - start with the Axiom of Extensionality
Restricted quantification
Restricted universal and existential quantification
r19.29imd
Metamath Proof Explorer
Description: Theorem 19.29 of Margaris p. 90 with an implication in the hypothesis
containing the generalization, deduction version. (Contributed by AV , 19-Jan-2019)
Ref
Expression
Hypotheses
r19.29imd.1
⊢ φ → ∃ x ∈ A ψ
r19.29imd.2
⊢ φ → ∀ x ∈ A ψ → χ
Assertion
r19.29imd
⊢ φ → ∃ x ∈ A ψ ∧ χ
Proof
Step
Hyp
Ref
Expression
1
r19.29imd.1
⊢ φ → ∃ x ∈ A ψ
2
r19.29imd.2
⊢ φ → ∀ x ∈ A ψ → χ
3
r19.29r
⊢ ∃ x ∈ A ψ ∧ ∀ x ∈ A ψ → χ → ∃ x ∈ A ψ ∧ ψ → χ
4
1 2 3
syl2anc
⊢ φ → ∃ x ∈ A ψ ∧ ψ → χ
5
abai
⊢ ψ ∧ χ ↔ ψ ∧ ψ → χ
6
5
rexbii
⊢ ∃ x ∈ A ψ ∧ χ ↔ ∃ x ∈ A ψ ∧ ψ → χ
7
4 6
sylibr
⊢ φ → ∃ x ∈ A ψ ∧ χ