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Theorem ax467to6 999
Description: Re-derivation of ax-6 953 from ax467 997. Note that ax-6 953 and ax-7 954 are not used by the re-derivation. The use of 19.20i 968 (which uses ax-4 951) is allowed since we have already proved ax467to4 998.
Assertion
Ref Expression
ax467to6 |- (-. A.x -. A.xph -> ph)

Proof of Theorem ax467to6
StepHypRef Expression
1 ax467to4 998 . . . 4 |- (A.xA.x -. A.xA.xph -> A.x -. A.xA.xph)
2 hba1 979 . . . . . 6 |- (A.xph -> A.xA.xph)
32con3i 98 . . . . 5 |- (-. A.xA.xph -> -. A.xph)
4319.20i 968 . . . 4 |- (A.x -. A.xA.xph -> A.x -. A.xph)
51, 4syl 10 . . 3 |- (A.xA.x -. A.xA.xph -> A.x -. A.xph)
65con3i 98 . 2 |- (-. A.x -. A.xph -> -. A.xA.x -. A.xA.xph)
7 pm2.21 76 . 2 |- (-. A.xA.x -. A.xA.xph -> (A.xA.x -. A.xA.xph -> A.xph))
8 ax467 997 . 2 |- ((A.xA.x -. A.xA.xph -> A.xph) -> ph)
96, 7, 83syl 20 1 |- (-. A.x -. A.xph -> ph)
Colors of variables: wff set class
Syntax hints:  -. wn 2   -> wi 3  A.wal 950
This theorem is referenced by:  ax467to7 1000
This theorem was proved from axioms:  ax-1 4  ax-2 5  ax-3 6  ax-mp 7  ax-4 951  ax-5 952  ax-6 953  ax-7 954  ax-gen 955
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