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Theorem dtrucor2 4892
 Description: The theorem form of the deduction dtrucor 4891 leads to a contradiction, as mentioned in the "Wrong!" example at mmdeduction.html#bad. (Contributed by NM, 20-Oct-2007.)
Hypothesis
Ref Expression
dtrucor2.1 (𝑥 = 𝑦𝑥𝑦)
Assertion
Ref Expression
dtrucor2 (𝜑 ∧ ¬ 𝜑)

Proof of Theorem dtrucor2
StepHypRef Expression
1 ax6e 2248 . 2 𝑥 𝑥 = 𝑦
2 dtrucor2.1 . . . . 5 (𝑥 = 𝑦𝑥𝑦)
32necon2bi 2821 . . . 4 (𝑥 = 𝑦 → ¬ 𝑥 = 𝑦)
4 pm2.01 180 . . . 4 ((𝑥 = 𝑦 → ¬ 𝑥 = 𝑦) → ¬ 𝑥 = 𝑦)
53, 4ax-mp 5 . . 3 ¬ 𝑥 = 𝑦
65nex 1729 . 2 ¬ ∃𝑥 𝑥 = 𝑦
71, 6pm2.24ii 117 1 (𝜑 ∧ ¬ 𝜑)
 Colors of variables: wff setvar class Syntax hints:  ¬ wn 3   → wi 4   ∧ wa 384  ∃wex 1702   ≠ wne 2791 This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1720  ax-4 1735  ax-5 1837  ax-6 1886  ax-7 1933  ax-12 2045  ax-13 2244 This theorem depends on definitions:  df-bi 197  df-an 386  df-ex 1703  df-ne 2792 This theorem is referenced by: (None)
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