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Theorem axc7 2311
Description: Show that the original axiom ax-c7 37755 can be derived from ax-10 2138 (hbn1 2139), sp 2177 and propositional calculus. See ax10fromc7 37765 for the rederivation of ax-10 2138 from ax-c7 37755.

Normally, axc7 2311 should be used rather than ax-c7 37755, except by theorems specifically studying the latter's properties. (Contributed by NM, 21-May-2008.)

Assertion
Ref Expression
axc7 (¬ ∀𝑥 ¬ ∀𝑥𝜑𝜑)

Proof of Theorem axc7
StepHypRef Expression
1 sp 2177 . 2 (∀𝑥𝜑𝜑)
2 hbn1 2139 . 2 (¬ ∀𝑥𝜑 → ∀𝑥 ¬ ∀𝑥𝜑)
31, 2nsyl4 158 1 (¬ ∀𝑥 ¬ ∀𝑥𝜑𝜑)
Colors of variables: wff setvar class
Syntax hints:  ¬ wn 3  wi 4  wal 1540
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1798  ax-4 1812  ax-5 1914  ax-6 1972  ax-7 2012  ax-10 2138  ax-12 2172
This theorem depends on definitions:  df-bi 206  df-ex 1783
This theorem is referenced by:  modal-b  2313  axc10  2385  hbntg  34777  bj-modalb  35594  bj-axc10v  35671  axc5c4c711  43160  hbntal  43314
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