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Axiom ax-nul 5228
Description: The Null Set Axiom of ZF set theory. It was derived as axnul 5227 above and is therefore redundant, but we state it as a separate axiom here so that its uses can be identified more easily. (Contributed by NM, 7-Aug-2003.)
Assertion
Ref Expression
ax-nul 𝑥𝑦 ¬ 𝑦𝑥
Distinct variable group:   𝑥,𝑦

Detailed syntax breakdown of Axiom ax-nul
StepHypRef Expression
1 vy . . . . 5 setvar 𝑦
2 vx . . . . 5 setvar 𝑥
31, 2wel 2107 . . . 4 wff 𝑦𝑥
43wn 3 . . 3 wff ¬ 𝑦𝑥
54, 1wal 1537 . 2 wff 𝑦 ¬ 𝑦𝑥
65, 2wex 1782 1 wff 𝑥𝑦 ¬ 𝑦𝑥
Colors of variables: wff setvar class
This axiom is referenced by:  0ex  5229  dtruALT2  5291  axprlem1  5344  axprlem4  5347  axprlem5  5348  dtru  5357  bj-dtru  35007  sn-dtru  40196  eu0  41117
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