Theorem suctr 6449

Description: The successor of a transitive class is transitive. (Contributed by Alan Sare, 11-Apr-2009.) (Proof shortened by JJ, 24-Sep-2021.)

Assertion

Ref	Expression
suctr	⊢ (Tr 𝐴 → Tr suc 𝐴)

Proof of Theorem suctr

Dummy variables 𝑦 𝑧 are mutually distinct and distinct from all other variables.

Step	Hyp	Ref	Expression
1		elsuci 6430	. . . . . 6 ⊢ (𝑦 ∈ suc 𝐴 → (𝑦 ∈ 𝐴 ∨ 𝑦 = 𝐴))
2		trel 5225	. . . . . . . 8 ⊢ (Tr 𝐴 → ((𝑧 ∈ 𝑦 ∧ 𝑦 ∈ 𝐴) → 𝑧 ∈ 𝐴))
3	2	expdimp 457	. . . . . . 7 ⊢ ((Tr 𝐴 ∧ 𝑧 ∈ 𝑦) → (𝑦 ∈ 𝐴 → 𝑧 ∈ 𝐴))
4		eleq2 2850	. . . . . . . . 9 ⊢ (𝑦 = 𝐴 → (𝑧 ∈ 𝑦 ↔ 𝑧 ∈ 𝐴))
5	4	biimpcd 252	. . . . . . . 8 ⊢ (𝑧 ∈ 𝑦 → (𝑦 = 𝐴 → 𝑧 ∈ 𝐴))
6	5	adantl 486	. . . . . . 7 ⊢ ((Tr 𝐴 ∧ 𝑧 ∈ 𝑦) → (𝑦 = 𝐴 → 𝑧 ∈ 𝐴))
7	3, 6	jaod 872	. . . . . 6 ⊢ ((Tr 𝐴 ∧ 𝑧 ∈ 𝑦) → ((𝑦 ∈ 𝐴 ∨ 𝑦 = 𝐴) → 𝑧 ∈ 𝐴))
8	1, 7	syl5 35	. . . . 5 ⊢ ((Tr 𝐴 ∧ 𝑧 ∈ 𝑦) → (𝑦 ∈ suc 𝐴 → 𝑧 ∈ 𝐴))
9	8	expimpd 458	. . . 4 ⊢ (Tr 𝐴 → ((𝑧 ∈ 𝑦 ∧ 𝑦 ∈ suc 𝐴) → 𝑧 ∈ 𝐴))
10		elelsuc 6436	. . . 4 ⊢ (𝑧 ∈ 𝐴 → 𝑧 ∈ suc 𝐴)
11	9, 10	syl6 36	. . 3 ⊢ (Tr 𝐴 → ((𝑧 ∈ 𝑦 ∧ 𝑦 ∈ suc 𝐴) → 𝑧 ∈ suc 𝐴))
12	11	alrimivv 1956	. 2 ⊢ (Tr 𝐴 → ∀𝑧∀𝑦((𝑧 ∈ 𝑦 ∧ 𝑦 ∈ suc 𝐴) → 𝑧 ∈ suc 𝐴))
13		dftr2 5219	. 2 ⊢ (Tr suc 𝐴 ↔ ∀𝑧∀𝑦((𝑧 ∈ 𝑦 ∧ 𝑦 ∈ suc 𝐴) → 𝑧 ∈ suc 𝐴))
14	12, 13	sylibr 237	1 ⊢ (Tr 𝐴 → Tr suc 𝐴)

Syntax hints:   → wi 4   ∧ wa 400   ∨ wo 860  ∀wal 1566   = wceq 1568   ∈ wcel 2141  Tr wtr 5217  suc csuc 6362

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1823  ax-4 1837  ax-5 1938  ax-6 1995  ax-7 2036  ax-8 2143  ax-9 2151  ax-ext 2733

This theorem depends on definitions:  df-bi 210  df-an 401  df-or 861  df-tru 1571  df-ex 1808  df-sb 2095  df-clab 2740  df-cleq 2753  df-clel 2836  df-v 3455  df-un 3909  df-ss 3921  df-sn 4589  df-uni 4872  df-tr 5218  df-suc 6366

This theorem is referenced by:  ordsuci  7806  dfon2lem3  36241  dfon2lem7  36245  dford3lem2  43724