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Theorem prlem1 862
 Description: A specialized lemma for set theory (to derive the Axiom of Pairing). (Contributed by NM, 18-Oct-1995.) (Proof shortened by Andrew Salmon, 13-May-2011.) (Proof shortened by Wolf Lammen, 5-Jan-2013.)
Hypotheses
Ref Expression
prlem1.1 (φ → (ηχ))
prlem1.2 (ψ → ¬ θ)
Assertion
Ref Expression
prlem1 (φ → (ψ → (((ψ χ) (θ τ)) → η)))

Proof of Theorem prlem1
StepHypRef Expression
1 prlem1.1 . . . . 5 (φ → (ηχ))
21biimprd 147 . . . 4 (φ → (χη))
32adantld 263 . . 3 (φ → ((ψ χ) → η))
4 prlem1.2 . . . . 5 (ψ → ¬ θ)
54pm2.21d 534 . . . 4 (ψ → (θη))
65adantrd 264 . . 3 (ψ → ((θ τ) → η))
73, 6jaao 623 . 2 ((φ ψ) → (((ψ χ) (θ τ)) → η))
87ex 108 1 (φ → (ψ → (((ψ χ) (θ τ)) → η)))
 Colors of variables: wff set class Syntax hints:  ¬ wn 3   → wi 4   ∧ wa 97   ↔ wb 98   ∨ wo 613 This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-mp 7  ax-ia1 99  ax-ia2 100  ax-ia3 101  ax-in2 530  ax-io 614 This theorem depends on definitions:  df-bi 110 This theorem is referenced by: (None)
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