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Theorem con3ALTVD 43290
Description: The following User's Proof is a Natural Deduction Sequent Calculus transcription of the Fitch-style Natural Deduction proof of Theorem 7 of Section 14 of [Margaris] p. 60 (which is con3 153). The same proof may also be interpreted to be a Virtual Deduction Hilbert-style axiomatic proof. It was completed automatically by the tools program completeusersproof.cmd, which invokes Mel L. O'Cat's mmj2 and Norm Megill's Metamath Proof Assistant. con3ALT2 42904 is con3ALTVD 43290 without virtual deductions and was automatically derived from con3ALTVD 43290. Step i of the User's Proof corresponds to step i of the Fitch-style proof.
1:: (   (𝜑𝜓)   ▶   (𝜑𝜓)   )
2:: (   (𝜑𝜓)   ,   ¬ ¬ 𝜑   ▶   ¬ ¬ 𝜑   )
3:: (¬ ¬ 𝜑𝜑)
4:2: (   (𝜑𝜓)   ,   ¬ ¬ 𝜑   ▶   𝜑   )
5:1,4: (   (𝜑𝜓)   ,   ¬ ¬ 𝜑   ▶   𝜓   )
6:: (𝜓 → ¬ ¬ 𝜓)
7:6,5: (   (𝜑𝜓)   ,   ¬ ¬ 𝜑   ▶   ¬ ¬ 𝜓   )
8:7: (   (𝜑𝜓)   ▶   (¬ ¬ 𝜑 → ¬ ¬ 𝜓 )   )
9:: ((¬ ¬ 𝜑 → ¬ ¬ 𝜓) → (¬ 𝜓 ¬ 𝜑))
10:8: (   (𝜑𝜓)   ▶   𝜓 → ¬ 𝜑)   )
qed:10: ((𝜑𝜓) → (¬ 𝜓 → ¬ 𝜑))
(Contributed by Alan Sare, 21-Apr-2013.) (Proof modification is discouraged.) (New usage is discouraged.)
Assertion
Ref Expression
con3ALTVD ((𝜑𝜓) → (¬ 𝜓 → ¬ 𝜑))

Proof of Theorem con3ALTVD
StepHypRef Expression
1 idn1 42948 . . . . . 6 (   (𝜑𝜓)   ▶   (𝜑𝜓)   )
2 idn2 42987 . . . . . . 7 (   (𝜑𝜓)   ,    ¬ ¬ 𝜑   ▶    ¬ ¬ 𝜑   )
3 notnotr 130 . . . . . . 7 (¬ ¬ 𝜑𝜑)
42, 3e2 43005 . . . . . 6 (   (𝜑𝜓)   ,    ¬ ¬ 𝜑   ▶   𝜑   )
5 id 22 . . . . . 6 ((𝜑𝜓) → (𝜑𝜓))
61, 4, 5e12 43098 . . . . 5 (   (𝜑𝜓)   ,    ¬ ¬ 𝜑   ▶   𝜓   )
7 notnot 142 . . . . 5 (𝜓 → ¬ ¬ 𝜓)
86, 7e2 43005 . . . 4 (   (𝜑𝜓)   ,    ¬ ¬ 𝜑   ▶    ¬ ¬ 𝜓   )
98in2 42979 . . 3 (   (𝜑𝜓)   ▶   (¬ ¬ 𝜑 → ¬ ¬ 𝜓)   )
10 con4 113 . . 3 ((¬ ¬ 𝜑 → ¬ ¬ 𝜓) → (¬ 𝜓 → ¬ 𝜑))
119, 10e1a 43001 . 2 (   (𝜑𝜓)   ▶   𝜓 → ¬ 𝜑)   )
1211in1 42945 1 ((𝜑𝜓) → (¬ 𝜓 → ¬ 𝜑))
Colors of variables: wff setvar class
Syntax hints:  ¬ wn 3  wi 4
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8
This theorem depends on definitions:  df-bi 206  df-an 398  df-vd1 42944  df-vd2 42952
This theorem is referenced by: (None)
  Copyright terms: Public domain W3C validator