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Theorem re1ax2lem 31552
 Description: Lemma for re1ax2 31553. (Contributed by Anthony Hart, 16-Aug-2011.) (Proof modification is discouraged.) (New usage is discouraged.)
Assertion
Ref Expression
re1ax2lem ((𝜑 → (𝜓𝜒)) → (𝜓 → (𝜑𝜒)))

Proof of Theorem re1ax2lem
StepHypRef Expression
1 tb-ax2 31549 . . . 4 (𝜓 → ((𝜓𝜒) → 𝜓))
2 tb-ax1 31548 . . . 4 (((𝜓𝜒) → 𝜓) → ((𝜓𝜒) → ((𝜓𝜒) → 𝜒)))
31, 2tbsyl 31551 . . 3 (𝜓 → ((𝜓𝜒) → ((𝜓𝜒) → 𝜒)))
4 tb-ax1 31548 . . . 4 (((𝜓𝜒) → ((𝜓𝜒) → 𝜒)) → ((((𝜓𝜒) → 𝜒) → 𝜒) → ((𝜓𝜒) → 𝜒)))
5 tb-ax3 31550 . . . 4 (((((𝜓𝜒) → 𝜒) → 𝜒) → ((𝜓𝜒) → 𝜒)) → ((𝜓𝜒) → 𝜒))
64, 5tbsyl 31551 . . 3 (((𝜓𝜒) → ((𝜓𝜒) → 𝜒)) → ((𝜓𝜒) → 𝜒))
73, 6tbsyl 31551 . 2 (𝜓 → ((𝜓𝜒) → 𝜒))
8 tb-ax1 31548 . 2 ((𝜑 → (𝜓𝜒)) → (((𝜓𝜒) → 𝜒) → (𝜑𝜒)))
9 tb-ax1 31548 . 2 ((𝜓 → ((𝜓𝜒) → 𝜒)) → ((((𝜓𝜒) → 𝜒) → (𝜑𝜒)) → (𝜓 → (𝜑𝜒))))
107, 8, 9mpsyl 66 1 ((𝜑 → (𝜓𝜒)) → (𝜓 → (𝜑𝜒)))
 Colors of variables: wff setvar class Syntax hints:   → wi 4 This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8 This theorem is referenced by:  re1ax2  31553
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