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Theorem pclem6 1374
Description: Negation inferred from embedded conjunct. (Contributed by NM, 20-Aug-1993.) (Proof rewritten by Jim Kingdon, 4-May-2018.)
Assertion
Ref Expression
pclem6 ((𝜑 ↔ (𝜓 ∧ ¬ 𝜑)) → ¬ 𝜓)

Proof of Theorem pclem6
StepHypRef Expression
1 biimp 118 . . . . 5 ((𝜑 ↔ (𝜓 ∧ ¬ 𝜑)) → (𝜑 → (𝜓 ∧ ¬ 𝜑)))
2 pm3.4 333 . . . . . 6 ((𝜓 ∧ ¬ 𝜑) → (𝜓 → ¬ 𝜑))
32com12 30 . . . . 5 (𝜓 → ((𝜓 ∧ ¬ 𝜑) → ¬ 𝜑))
41, 3syl9r 73 . . . 4 (𝜓 → ((𝜑 ↔ (𝜓 ∧ ¬ 𝜑)) → (𝜑 → ¬ 𝜑)))
5 ax-ia3 108 . . . . 5 (𝜓 → (¬ 𝜑 → (𝜓 ∧ ¬ 𝜑)))
6 biimpr 130 . . . . 5 ((𝜑 ↔ (𝜓 ∧ ¬ 𝜑)) → ((𝜓 ∧ ¬ 𝜑) → 𝜑))
75, 6syl9 72 . . . 4 (𝜓 → ((𝜑 ↔ (𝜓 ∧ ¬ 𝜑)) → (¬ 𝜑𝜑)))
84, 7impbidd 127 . . 3 (𝜓 → ((𝜑 ↔ (𝜓 ∧ ¬ 𝜑)) → (𝜑 ↔ ¬ 𝜑)))
9 pm5.19 706 . . . 4 ¬ (𝜑 ↔ ¬ 𝜑)
109pm2.21i 646 . . 3 ((𝜑 ↔ ¬ 𝜑) → ⊥)
118, 10syl6com 35 . 2 ((𝜑 ↔ (𝜓 ∧ ¬ 𝜑)) → (𝜓 → ⊥))
12 dfnot 1371 . 2 𝜓 ↔ (𝜓 → ⊥))
1311, 12sylibr 134 1 ((𝜑 ↔ (𝜓 ∧ ¬ 𝜑)) → ¬ 𝜓)
Colors of variables: wff set class
Syntax hints:  ¬ wn 3  wi 4  wa 104  wb 105  wfal 1358
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-ia1 106  ax-ia2 107  ax-ia3 108  ax-in1 614  ax-in2 615
This theorem depends on definitions:  df-bi 117  df-tru 1356  df-fal 1359
This theorem is referenced by:  nalset  4133  pwnss  4159  bj-nalset  14583
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