Metamath Proof Explorer


Theorem efgsp1

Description: If F is an extension sequence and A is an extension of the last element of F , then F + <" A "> is an extension sequence. (Contributed by Mario Carneiro, 1-Oct-2015)

Ref Expression
Hypotheses efgval.w ⊢ W = I ⁡ Word I × 2 𝑜
efgval.r ⊢ ∼ ˙ = ~ FG ⁡ I
efgval2.m ⊢ M = y ∈ I , z ∈ 2 𝑜 ⟼ y 1 𝑜 ∖ z
efgval2.t ⊢ T = v ∈ W ⟼ n ∈ 0 … v , w ∈ I × 2 𝑜 ⟼ v splice n n ⟨“ w M ⁡ w ”⟩
efgred.d ⊢ D = W ∖ ⋃ x ∈ W ran ⁡ T ⁡ x
efgred.s ⊢ S = m ∈ t ∈ Word W ∖ ∅ | t ⁡ 0 ∈ D ∧ ∀ k ∈ 1 ..^ t t ⁡ k ∈ ran ⁡ T ⁡ t ⁡ k − 1 ⟼ m ⁡ m − 1
Assertion efgsp1 ⊢ F ∈ dom ⁡ S ∧ A ∈ ran ⁡ T ⁡ S ⁡ F → F ++ ⟨“ A ”⟩ ∈ dom ⁡ S

Proof

Step Hyp Ref Expression
1 efgval.w ⊢ W = I ⁡ Word I × 2 𝑜
2 efgval.r ⊢ ∼ ˙ = ~ FG ⁡ I
3 efgval2.m ⊢ M = y ∈ I , z ∈ 2 𝑜 ⟼ y 1 𝑜 ∖ z
4 efgval2.t ⊢ T = v ∈ W ⟼ n ∈ 0 … v , w ∈ I × 2 𝑜 ⟼ v splice n n ⟨“ w M ⁡ w ”⟩
5 efgred.d ⊢ D = W ∖ ⋃ x ∈ W ran ⁡ T ⁡ x
6 efgred.s ⊢ S = m ∈ t ∈ Word W ∖ ∅ | t ⁡ 0 ∈ D ∧ ∀ k ∈ 1 ..^ t t ⁡ k ∈ ran ⁡ T ⁡ t ⁡ k − 1 ⟼ m ⁡ m − 1
7 1 2 3 4 5 6 efgsdm ⊢ F ∈ dom ⁡ S ↔ F ∈ Word W ∖ ∅ ∧ F ⁡ 0 ∈ D ∧ ∀ i ∈ 1 ..^ F F ⁡ i ∈ ran ⁡ T ⁡ F ⁡ i − 1
8 7 simp1bi ⊢ F ∈ dom ⁡ S → F ∈ Word W ∖ ∅
9 8 eldifad ⊢ F ∈ dom ⁡ S → F ∈ Word W
10 1 2 3 4 5 6 efgsf ⊢ S : t ∈ Word W ∖ ∅ | t ⁡ 0 ∈ D ∧ ∀ k ∈ 1 ..^ t t ⁡ k ∈ ran ⁡ T ⁡ t ⁡ k − 1 ⟶ W
11 10 fdmi ⊢ dom ⁡ S = t ∈ Word W ∖ ∅ | t ⁡ 0 ∈ D ∧ ∀ k ∈ 1 ..^ t t ⁡ k ∈ ran ⁡ T ⁡ t ⁡ k − 1
12 11 feq2i ⊢ S : dom ⁡ S ⟶ W ↔ S : t ∈ Word W ∖ ∅ | t ⁡ 0 ∈ D ∧ ∀ k ∈ 1 ..^ t t ⁡ k ∈ ran ⁡ T ⁡ t ⁡ k − 1 ⟶ W
13 10 12 mpbir ⊢ S : dom ⁡ S ⟶ W
14 13 ffvelcdmi ⊢ F ∈ dom ⁡ S → S ⁡ F ∈ W
15 1 2 3 4 efgtf ⊢ S ⁡ F ∈ W → T ⁡ S ⁡ F = a ∈ 0 … S ⁡ F , i ∈ I × 2 𝑜 ⟼ S ⁡ F splice a a ⟨“ i M ⁡ i ”⟩ ∧ T ⁡ S ⁡ F : 0 … S ⁡ F × I × 2 𝑜 ⟶ W
16 14 15 syl ⊢ F ∈ dom ⁡ S → T ⁡ S ⁡ F = a ∈ 0 … S ⁡ F , i ∈ I × 2 𝑜 ⟼ S ⁡ F splice a a ⟨“ i M ⁡ i ”⟩ ∧ T ⁡ S ⁡ F : 0 … S ⁡ F × I × 2 𝑜 ⟶ W
17 16 simprd ⊢ F ∈ dom ⁡ S → T ⁡ S ⁡ F : 0 … S ⁡ F × I × 2 𝑜 ⟶ W
18 17 frnd ⊢ F ∈ dom ⁡ S → ran ⁡ T ⁡ S ⁡ F ⊆ W
19 18 sselda ⊢ F ∈ dom ⁡ S ∧ A ∈ ran ⁡ T ⁡ S ⁡ F → A ∈ W
20 19 s1cld ⊢ F ∈ dom ⁡ S ∧ A ∈ ran ⁡ T ⁡ S ⁡ F → ⟨“ A ”⟩ ∈ Word W
21 ccatcl ⊢ F ∈ Word W ∧ ⟨“ A ”⟩ ∈ Word W → F ++ ⟨“ A ”⟩ ∈ Word W
22 9 20 21 syl2an2r ⊢ F ∈ dom ⁡ S ∧ A ∈ ran ⁡ T ⁡ S ⁡ F → F ++ ⟨“ A ”⟩ ∈ Word W
23 ccatws1n0 ⊢ F ∈ Word W → F ++ ⟨“ A ”⟩ ≠ ∅
24 9 23 syl ⊢ F ∈ dom ⁡ S → F ++ ⟨“ A ”⟩ ≠ ∅
25 24 adantr ⊢ F ∈ dom ⁡ S ∧ A ∈ ran ⁡ T ⁡ S ⁡ F → F ++ ⟨“ A ”⟩ ≠ ∅
26 eldifsn ⊢ F ++ ⟨“ A ”⟩ ∈ Word W ∖ ∅ ↔ F ++ ⟨“ A ”⟩ ∈ Word W ∧ F ++ ⟨“ A ”⟩ ≠ ∅
27 22 25 26 sylanbrc ⊢ F ∈ dom ⁡ S ∧ A ∈ ran ⁡ T ⁡ S ⁡ F → F ++ ⟨“ A ”⟩ ∈ Word W ∖ ∅
28 9 adantr ⊢ F ∈ dom ⁡ S ∧ A ∈ ran ⁡ T ⁡ S ⁡ F → F ∈ Word W
29 eldifsni ⊢ F ∈ Word W ∖ ∅ → F ≠ ∅
30 8 29 syl ⊢ F ∈ dom ⁡ S → F ≠ ∅
31 len0nnbi ⊢ F ∈ Word W → F ≠ ∅ ↔ F ∈ ℕ
32 9 31 syl ⊢ F ∈ dom ⁡ S → F ≠ ∅ ↔ F ∈ ℕ
33 30 32 mpbid ⊢ F ∈ dom ⁡ S → F ∈ ℕ
34 lbfzo0 ⊢ 0 ∈ 0 ..^ F ↔ F ∈ ℕ
35 33 34 sylibr ⊢ F ∈ dom ⁡ S → 0 ∈ 0 ..^ F
36 35 adantr ⊢ F ∈ dom ⁡ S ∧ A ∈ ran ⁡ T ⁡ S ⁡ F → 0 ∈ 0 ..^ F
37 ccatval1 ⊢ F ∈ Word W ∧ ⟨“ A ”⟩ ∈ Word W ∧ 0 ∈ 0 ..^ F → F ++ ⟨“ A ”⟩ ⁡ 0 = F ⁡ 0
38 28 20 36 37 syl3anc ⊢ F ∈ dom ⁡ S ∧ A ∈ ran ⁡ T ⁡ S ⁡ F → F ++ ⟨“ A ”⟩ ⁡ 0 = F ⁡ 0
39 7 simp2bi ⊢ F ∈ dom ⁡ S → F ⁡ 0 ∈ D
40 39 adantr ⊢ F ∈ dom ⁡ S ∧ A ∈ ran ⁡ T ⁡ S ⁡ F → F ⁡ 0 ∈ D
41 38 40 eqeltrd ⊢ F ∈ dom ⁡ S ∧ A ∈ ran ⁡ T ⁡ S ⁡ F → F ++ ⟨“ A ”⟩ ⁡ 0 ∈ D
42 7 simp3bi ⊢ F ∈ dom ⁡ S → ∀ i ∈ 1 ..^ F F ⁡ i ∈ ran ⁡ T ⁡ F ⁡ i − 1
43 42 adantr ⊢ F ∈ dom ⁡ S ∧ A ∈ ran ⁡ T ⁡ S ⁡ F → ∀ i ∈ 1 ..^ F F ⁡ i ∈ ran ⁡ T ⁡ F ⁡ i − 1
44 fzo0ss1 ⊢ 1 ..^ F ⊆ 0 ..^ F
45 44 sseli ⊢ i ∈ 1 ..^ F → i ∈ 0 ..^ F
46 ccatval1 ⊢ F ∈ Word W ∧ ⟨“ A ”⟩ ∈ Word W ∧ i ∈ 0 ..^ F → F ++ ⟨“ A ”⟩ ⁡ i = F ⁡ i
47 45 46 syl3an3 ⊢ F ∈ Word W ∧ ⟨“ A ”⟩ ∈ Word W ∧ i ∈ 1 ..^ F → F ++ ⟨“ A ”⟩ ⁡ i = F ⁡ i
48 elfzoel2 ⊢ i ∈ 1 ..^ F → F ∈ ℤ
49 peano2zm ⊢ F ∈ ℤ → F − 1 ∈ ℤ
50 48 49 syl ⊢ i ∈ 1 ..^ F → F − 1 ∈ ℤ
51 48 zred ⊢ i ∈ 1 ..^ F → F ∈ ℝ
52 51 lem1d ⊢ i ∈ 1 ..^ F → F − 1 ≤ F
53 eluz2 ⊢ F ∈ ℤ ≥ F − 1 ↔ F − 1 ∈ ℤ ∧ F ∈ ℤ ∧ F − 1 ≤ F
54 50 48 52 53 syl3anbrc ⊢ i ∈ 1 ..^ F → F ∈ ℤ ≥ F − 1
55 fzoss2 ⊢ F ∈ ℤ ≥ F − 1 → 0 ..^ F − 1 ⊆ 0 ..^ F
56 54 55 syl ⊢ i ∈ 1 ..^ F → 0 ..^ F − 1 ⊆ 0 ..^ F
57 elfzo1elm1fzo0 ⊢ i ∈ 1 ..^ F → i − 1 ∈ 0 ..^ F − 1
58 56 57 sseldd ⊢ i ∈ 1 ..^ F → i − 1 ∈ 0 ..^ F
59 ccatval1 ⊢ F ∈ Word W ∧ ⟨“ A ”⟩ ∈ Word W ∧ i − 1 ∈ 0 ..^ F → F ++ ⟨“ A ”⟩ ⁡ i − 1 = F ⁡ i − 1
60 58 59 syl3an3 ⊢ F ∈ Word W ∧ ⟨“ A ”⟩ ∈ Word W ∧ i ∈ 1 ..^ F → F ++ ⟨“ A ”⟩ ⁡ i − 1 = F ⁡ i − 1
61 60 fveq2d ⊢ F ∈ Word W ∧ ⟨“ A ”⟩ ∈ Word W ∧ i ∈ 1 ..^ F → T ⁡ F ++ ⟨“ A ”⟩ ⁡ i − 1 = T ⁡ F ⁡ i − 1
62 61 rneqd ⊢ F ∈ Word W ∧ ⟨“ A ”⟩ ∈ Word W ∧ i ∈ 1 ..^ F → ran ⁡ T ⁡ F ++ ⟨“ A ”⟩ ⁡ i − 1 = ran ⁡ T ⁡ F ⁡ i − 1
63 47 62 eleq12d ⊢ F ∈ Word W ∧ ⟨“ A ”⟩ ∈ Word W ∧ i ∈ 1 ..^ F → F ++ ⟨“ A ”⟩ ⁡ i ∈ ran ⁡ T ⁡ F ++ ⟨“ A ”⟩ ⁡ i − 1 ↔ F ⁡ i ∈ ran ⁡ T ⁡ F ⁡ i − 1
64 63 3expa ⊢ F ∈ Word W ∧ ⟨“ A ”⟩ ∈ Word W ∧ i ∈ 1 ..^ F → F ++ ⟨“ A ”⟩ ⁡ i ∈ ran ⁡ T ⁡ F ++ ⟨“ A ”⟩ ⁡ i − 1 ↔ F ⁡ i ∈ ran ⁡ T ⁡ F ⁡ i − 1
65 64 ralbidva ⊢ F ∈ Word W ∧ ⟨“ A ”⟩ ∈ Word W → ∀ i ∈ 1 ..^ F F ++ ⟨“ A ”⟩ ⁡ i ∈ ran ⁡ T ⁡ F ++ ⟨“ A ”⟩ ⁡ i − 1 ↔ ∀ i ∈ 1 ..^ F F ⁡ i ∈ ran ⁡ T ⁡ F ⁡ i − 1
66 9 20 65 syl2an2r ⊢ F ∈ dom ⁡ S ∧ A ∈ ran ⁡ T ⁡ S ⁡ F → ∀ i ∈ 1 ..^ F F ++ ⟨“ A ”⟩ ⁡ i ∈ ran ⁡ T ⁡ F ++ ⟨“ A ”⟩ ⁡ i − 1 ↔ ∀ i ∈ 1 ..^ F F ⁡ i ∈ ran ⁡ T ⁡ F ⁡ i − 1
67 43 66 mpbird ⊢ F ∈ dom ⁡ S ∧ A ∈ ran ⁡ T ⁡ S ⁡ F → ∀ i ∈ 1 ..^ F F ++ ⟨“ A ”⟩ ⁡ i ∈ ran ⁡ T ⁡ F ++ ⟨“ A ”⟩ ⁡ i − 1
68 lencl ⊢ F ∈ Word W → F ∈ ℕ 0
69 9 68 syl ⊢ F ∈ dom ⁡ S → F ∈ ℕ 0
70 69 nn0cnd ⊢ F ∈ dom ⁡ S → F ∈ ℂ
71 70 addlidd ⊢ F ∈ dom ⁡ S → 0 + F = F
72 71 fveq2d ⊢ F ∈ dom ⁡ S → F ++ ⟨“ A ”⟩ ⁡ 0 + F = F ++ ⟨“ A ”⟩ ⁡ F
73 72 adantr ⊢ F ∈ dom ⁡ S ∧ A ∈ ran ⁡ T ⁡ S ⁡ F → F ++ ⟨“ A ”⟩ ⁡ 0 + F = F ++ ⟨“ A ”⟩ ⁡ F
74 s1len ⊢ ⟨“ A ”⟩ = 1
75 1nn ⊢ 1 ∈ ℕ
76 74 75 eqeltri ⊢ ⟨“ A ”⟩ ∈ ℕ
77 lbfzo0 ⊢ 0 ∈ 0 ..^ ⟨“ A ”⟩ ↔ ⟨“ A ”⟩ ∈ ℕ
78 76 77 mpbir ⊢ 0 ∈ 0 ..^ ⟨“ A ”⟩
79 78 a1i ⊢ F ∈ dom ⁡ S ∧ A ∈ ran ⁡ T ⁡ S ⁡ F → 0 ∈ 0 ..^ ⟨“ A ”⟩
80 ccatval3 ⊢ F ∈ Word W ∧ ⟨“ A ”⟩ ∈ Word W ∧ 0 ∈ 0 ..^ ⟨“ A ”⟩ → F ++ ⟨“ A ”⟩ ⁡ 0 + F = ⟨“ A ”⟩ ⁡ 0
81 28 20 79 80 syl3anc ⊢ F ∈ dom ⁡ S ∧ A ∈ ran ⁡ T ⁡ S ⁡ F → F ++ ⟨“ A ”⟩ ⁡ 0 + F = ⟨“ A ”⟩ ⁡ 0
82 73 81 eqtr3d ⊢ F ∈ dom ⁡ S ∧ A ∈ ran ⁡ T ⁡ S ⁡ F → F ++ ⟨“ A ”⟩ ⁡ F = ⟨“ A ”⟩ ⁡ 0
83 simpr ⊢ F ∈ dom ⁡ S ∧ A ∈ ran ⁡ T ⁡ S ⁡ F → A ∈ ran ⁡ T ⁡ S ⁡ F
84 s1fv ⊢ A ∈ ran ⁡ T ⁡ S ⁡ F → ⟨“ A ”⟩ ⁡ 0 = A
85 84 adantl ⊢ F ∈ dom ⁡ S ∧ A ∈ ran ⁡ T ⁡ S ⁡ F → ⟨“ A ”⟩ ⁡ 0 = A
86 fzo0end ⊢ F ∈ ℕ → F − 1 ∈ 0 ..^ F
87 33 86 syl ⊢ F ∈ dom ⁡ S → F − 1 ∈ 0 ..^ F
88 87 adantr ⊢ F ∈ dom ⁡ S ∧ A ∈ ran ⁡ T ⁡ S ⁡ F → F − 1 ∈ 0 ..^ F
89 ccatval1 ⊢ F ∈ Word W ∧ ⟨“ A ”⟩ ∈ Word W ∧ F − 1 ∈ 0 ..^ F → F ++ ⟨“ A ”⟩ ⁡ F − 1 = F ⁡ F − 1
90 28 20 88 89 syl3anc ⊢ F ∈ dom ⁡ S ∧ A ∈ ran ⁡ T ⁡ S ⁡ F → F ++ ⟨“ A ”⟩ ⁡ F − 1 = F ⁡ F − 1
91 1 2 3 4 5 6 efgsval ⊢ F ∈ dom ⁡ S → S ⁡ F = F ⁡ F − 1
92 91 adantr ⊢ F ∈ dom ⁡ S ∧ A ∈ ran ⁡ T ⁡ S ⁡ F → S ⁡ F = F ⁡ F − 1
93 90 92 eqtr4d ⊢ F ∈ dom ⁡ S ∧ A ∈ ran ⁡ T ⁡ S ⁡ F → F ++ ⟨“ A ”⟩ ⁡ F − 1 = S ⁡ F
94 93 fveq2d ⊢ F ∈ dom ⁡ S ∧ A ∈ ran ⁡ T ⁡ S ⁡ F → T ⁡ F ++ ⟨“ A ”⟩ ⁡ F − 1 = T ⁡ S ⁡ F
95 94 rneqd ⊢ F ∈ dom ⁡ S ∧ A ∈ ran ⁡ T ⁡ S ⁡ F → ran ⁡ T ⁡ F ++ ⟨“ A ”⟩ ⁡ F − 1 = ran ⁡ T ⁡ S ⁡ F
96 83 85 95 3eltr4d ⊢ F ∈ dom ⁡ S ∧ A ∈ ran ⁡ T ⁡ S ⁡ F → ⟨“ A ”⟩ ⁡ 0 ∈ ran ⁡ T ⁡ F ++ ⟨“ A ”⟩ ⁡ F − 1
97 82 96 eqeltrd ⊢ F ∈ dom ⁡ S ∧ A ∈ ran ⁡ T ⁡ S ⁡ F → F ++ ⟨“ A ”⟩ ⁡ F ∈ ran ⁡ T ⁡ F ++ ⟨“ A ”⟩ ⁡ F − 1
98 fvex ⊢ F ∈ V
99 fveq2 ⊢ i = F → F ++ ⟨“ A ”⟩ ⁡ i = F ++ ⟨“ A ”⟩ ⁡ F
100 fvoveq1 ⊢ i = F → F ++ ⟨“ A ”⟩ ⁡ i − 1 = F ++ ⟨“ A ”⟩ ⁡ F − 1
101 100 fveq2d ⊢ i = F → T ⁡ F ++ ⟨“ A ”⟩ ⁡ i − 1 = T ⁡ F ++ ⟨“ A ”⟩ ⁡ F − 1
102 101 rneqd ⊢ i = F → ran ⁡ T ⁡ F ++ ⟨“ A ”⟩ ⁡ i − 1 = ran ⁡ T ⁡ F ++ ⟨“ A ”⟩ ⁡ F − 1
103 99 102 eleq12d ⊢ i = F → F ++ ⟨“ A ”⟩ ⁡ i ∈ ran ⁡ T ⁡ F ++ ⟨“ A ”⟩ ⁡ i − 1 ↔ F ++ ⟨“ A ”⟩ ⁡ F ∈ ran ⁡ T ⁡ F ++ ⟨“ A ”⟩ ⁡ F − 1
104 98 103 ralsn ⊢ ∀ i ∈ F F ++ ⟨“ A ”⟩ ⁡ i ∈ ran ⁡ T ⁡ F ++ ⟨“ A ”⟩ ⁡ i − 1 ↔ F ++ ⟨“ A ”⟩ ⁡ F ∈ ran ⁡ T ⁡ F ++ ⟨“ A ”⟩ ⁡ F − 1
105 97 104 sylibr ⊢ F ∈ dom ⁡ S ∧ A ∈ ran ⁡ T ⁡ S ⁡ F → ∀ i ∈ F F ++ ⟨“ A ”⟩ ⁡ i ∈ ran ⁡ T ⁡ F ++ ⟨“ A ”⟩ ⁡ i − 1
106 ralunb ⊢ ∀ i ∈ 1 ..^ F ∪ F F ++ ⟨“ A ”⟩ ⁡ i ∈ ran ⁡ T ⁡ F ++ ⟨“ A ”⟩ ⁡ i − 1 ↔ ∀ i ∈ 1 ..^ F F ++ ⟨“ A ”⟩ ⁡ i ∈ ran ⁡ T ⁡ F ++ ⟨“ A ”⟩ ⁡ i − 1 ∧ ∀ i ∈ F F ++ ⟨“ A ”⟩ ⁡ i ∈ ran ⁡ T ⁡ F ++ ⟨“ A ”⟩ ⁡ i − 1
107 67 105 106 sylanbrc ⊢ F ∈ dom ⁡ S ∧ A ∈ ran ⁡ T ⁡ S ⁡ F → ∀ i ∈ 1 ..^ F ∪ F F ++ ⟨“ A ”⟩ ⁡ i ∈ ran ⁡ T ⁡ F ++ ⟨“ A ”⟩ ⁡ i − 1
108 ccatlen ⊢ F ∈ Word W ∧ ⟨“ A ”⟩ ∈ Word W → F ++ ⟨“ A ”⟩ = F + ⟨“ A ”⟩
109 9 20 108 syl2an2r ⊢ F ∈ dom ⁡ S ∧ A ∈ ran ⁡ T ⁡ S ⁡ F → F ++ ⟨“ A ”⟩ = F + ⟨“ A ”⟩
110 74 oveq2i ⊢ F + ⟨“ A ”⟩ = F + 1
111 109 110 eqtrdi ⊢ F ∈ dom ⁡ S ∧ A ∈ ran ⁡ T ⁡ S ⁡ F → F ++ ⟨“ A ”⟩ = F + 1
112 111 oveq2d ⊢ F ∈ dom ⁡ S ∧ A ∈ ran ⁡ T ⁡ S ⁡ F → 1 ..^ F ++ ⟨“ A ”⟩ = 1 ..^ F + 1
113 nnuz ⊢ ℕ = ℤ ≥ 1
114 33 113 eleqtrdi ⊢ F ∈ dom ⁡ S → F ∈ ℤ ≥ 1
115 fzosplitsn ⊢ F ∈ ℤ ≥ 1 → 1 ..^ F + 1 = 1 ..^ F ∪ F
116 114 115 syl ⊢ F ∈ dom ⁡ S → 1 ..^ F + 1 = 1 ..^ F ∪ F
117 116 adantr ⊢ F ∈ dom ⁡ S ∧ A ∈ ran ⁡ T ⁡ S ⁡ F → 1 ..^ F + 1 = 1 ..^ F ∪ F
118 112 117 eqtrd ⊢ F ∈ dom ⁡ S ∧ A ∈ ran ⁡ T ⁡ S ⁡ F → 1 ..^ F ++ ⟨“ A ”⟩ = 1 ..^ F ∪ F
119 107 118 raleqtrrdv ⊢ F ∈ dom ⁡ S ∧ A ∈ ran ⁡ T ⁡ S ⁡ F → ∀ i ∈ 1 ..^ F ++ ⟨“ A ”⟩ F ++ ⟨“ A ”⟩ ⁡ i ∈ ran ⁡ T ⁡ F ++ ⟨“ A ”⟩ ⁡ i − 1
120 1 2 3 4 5 6 efgsdm ⊢ F ++ ⟨“ A ”⟩ ∈ dom ⁡ S ↔ F ++ ⟨“ A ”⟩ ∈ Word W ∖ ∅ ∧ F ++ ⟨“ A ”⟩ ⁡ 0 ∈ D ∧ ∀ i ∈ 1 ..^ F ++ ⟨“ A ”⟩ F ++ ⟨“ A ”⟩ ⁡ i ∈ ran ⁡ T ⁡ F ++ ⟨“ A ”⟩ ⁡ i − 1
121 27 41 119 120 syl3anbrc ⊢ F ∈ dom ⁡ S ∧ A ∈ ran ⁡ T ⁡ S ⁡ F → F ++ ⟨“ A ”⟩ ∈ dom ⁡ S