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Theorem ax-9 1355
Description: Derive ax-9 1355 from ax-i9 1354, the modified version for intuitionistic logic. Although ax-9 1355 does hold intuistionistically, in intuitionistic logic it is weaker than ax-i9 1354. (Contributed by NM, 3-Feb-2015.)
Assertion
Ref Expression
ax-9

Proof of Theorem ax-9
StepHypRef Expression
1 ax-i9 1354 . . 3
21notnoti 555 . 2
3 alnex 1320 . 2
42, 3mtbir 577 1
Colors of variables: wff set class
Syntax hints:   wn 3  wal 1266  wex 1313   wceq 1324
This theorem is referenced by:  equidqe  1356  equidqeOLD  1357
This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-mp 7  ax-ia1 97  ax-ia2 98  ax-ia3 99  ax-in1 527  ax-in2 528  ax-5 1267  ax-gen 1269  ax-ie2 1315  ax-i9 1354
This theorem depends on definitions:  df-bi 108  df-tru 1190  df-fal 1191
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