Theorem tbwlem2 1735

Description: Used to rederive the Lukasiewicz axioms from Tarski-Bernays-Wajsberg'. (Contributed by Anthony Hart, 16-Aug-2011.) (Proof modification is discouraged.) (New usage is discouraged.)

Assertion

Ref	Expression
tbwlem2	⊢ ((𝜑 → (𝜓 → ⊥)) → (((𝜑 → 𝜒) → 𝜃) → (𝜓 → 𝜃)))

Proof of Theorem tbwlem2

Step	Hyp	Ref	Expression
1		tbw-ax1 1729	. . 3 ⊢ ((𝜑 → (𝜓 → ⊥)) → (((𝜓 → ⊥) → 𝜒) → (𝜑 → 𝜒)))
2		tbw-ax4 1732	. . . . . 6 ⊢ (⊥ → 𝜒)
3		tbw-ax1 1729	. . . . . . 7 ⊢ ((𝜓 → ⊥) → ((⊥ → 𝜒) → (𝜓 → 𝜒)))
4		tbwlem1 1734	. . . . . . 7 ⊢ (((𝜓 → ⊥) → ((⊥ → 𝜒) → (𝜓 → 𝜒))) → ((⊥ → 𝜒) → ((𝜓 → ⊥) → (𝜓 → 𝜒))))
5	3, 4	ax-mp 5	. . . . . 6 ⊢ ((⊥ → 𝜒) → ((𝜓 → ⊥) → (𝜓 → 𝜒)))
6	2, 5	ax-mp 5	. . . . 5 ⊢ ((𝜓 → ⊥) → (𝜓 → 𝜒))
7		tbwlem1 1734	. . . . 5 ⊢ (((𝜓 → ⊥) → (𝜓 → 𝜒)) → (𝜓 → ((𝜓 → ⊥) → 𝜒)))
8	6, 7	ax-mp 5	. . . 4 ⊢ (𝜓 → ((𝜓 → ⊥) → 𝜒))
9		tbw-ax1 1729	. . . 4 ⊢ ((𝜓 → ((𝜓 → ⊥) → 𝜒)) → ((((𝜓 → ⊥) → 𝜒) → (𝜑 → 𝜒)) → (𝜓 → (𝜑 → 𝜒))))
10	8, 9	ax-mp 5	. . 3 ⊢ ((((𝜓 → ⊥) → 𝜒) → (𝜑 → 𝜒)) → (𝜓 → (𝜑 → 𝜒)))
11	1, 10	tbwsyl 1733	. 2 ⊢ ((𝜑 → (𝜓 → ⊥)) → (𝜓 → (𝜑 → 𝜒)))
12		tbw-ax1 1729	. 2 ⊢ ((𝜓 → (𝜑 → 𝜒)) → (((𝜑 → 𝜒) → 𝜃) → (𝜓 → 𝜃)))
13	11, 12	tbwsyl 1733	1 ⊢ ((𝜑 → (𝜓 → ⊥)) → (((𝜑 → 𝜒) → 𝜃) → (𝜓 → 𝜃)))

This proof depends on syntax axioms:   → wi 4  ⊥wfal 1581

This proof depends on axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8

This proof depends on definitions:  df-bi 210  df-tru 1572  df-fal 1582

This theorem is used by:  tbwlem4  1737