Metamath Proof Explorer


Theorem mdetunilem8

Description: Lemma for mdetuni . (Contributed by SO, 15-Jul-2018)

Ref Expression
Hypotheses mdetuni.a ⊢ A = N Mat R
mdetuni.b ⊢ B = Base A
mdetuni.k ⊢ K = Base R
mdetuni.0g ⊢ 0 ˙ = 0 R
mdetuni.1r ⊢ 1 ˙ = 1 R
mdetuni.pg ⊢ + ˙ = + R
mdetuni.tg ⊢ · ˙ = ⋅ R
mdetuni.n ⊢ φ → N ∈ Fin
mdetuni.r ⊢ φ → R ∈ Ring
mdetuni.ff ⊢ φ → D : B ⟶ K
mdetuni.al ⊢ φ → ∀ x ∈ B ∀ y ∈ N ∀ z ∈ N y ≠ z ∧ ∀ w ∈ N y x w = z x w → D ⁡ x = 0 ˙
mdetuni.li ⊢ φ → ∀ x ∈ B ∀ y ∈ B ∀ z ∈ B ∀ w ∈ N x ↾ w × N = y ↾ w × N + ˙ f z ↾ w × N ∧ x ↾ N ∖ w × N = y ↾ N ∖ w × N ∧ x ↾ N ∖ w × N = z ↾ N ∖ w × N → D ⁡ x = D ⁡ y + ˙ D ⁡ z
mdetuni.sc ⊢ φ → ∀ x ∈ B ∀ y ∈ K ∀ z ∈ B ∀ w ∈ N x ↾ w × N = w × N × y · ˙ f z ↾ w × N ∧ x ↾ N ∖ w × N = z ↾ N ∖ w × N → D ⁡ x = y · ˙ D ⁡ z
mdetunilem8.id ⊢ φ → D ⁡ 1 A = 0 ˙
Assertion mdetunilem8 ⊢ φ ∧ E : N ⟶ N → D ⁡ a ∈ N , b ∈ N ⟼ if E ⁡ a = b 1 ˙ 0 ˙ = 0 ˙

Proof

Step Hyp Ref Expression
1 mdetuni.a ⊢ A = N Mat R
2 mdetuni.b ⊢ B = Base A
3 mdetuni.k ⊢ K = Base R
4 mdetuni.0g ⊢ 0 ˙ = 0 R
5 mdetuni.1r ⊢ 1 ˙ = 1 R
6 mdetuni.pg ⊢ + ˙ = + R
7 mdetuni.tg ⊢ · ˙ = ⋅ R
8 mdetuni.n ⊢ φ → N ∈ Fin
9 mdetuni.r ⊢ φ → R ∈ Ring
10 mdetuni.ff ⊢ φ → D : B ⟶ K
11 mdetuni.al ⊢ φ → ∀ x ∈ B ∀ y ∈ N ∀ z ∈ N y ≠ z ∧ ∀ w ∈ N y x w = z x w → D ⁡ x = 0 ˙
12 mdetuni.li ⊢ φ → ∀ x ∈ B ∀ y ∈ B ∀ z ∈ B ∀ w ∈ N x ↾ w × N = y ↾ w × N + ˙ f z ↾ w × N ∧ x ↾ N ∖ w × N = y ↾ N ∖ w × N ∧ x ↾ N ∖ w × N = z ↾ N ∖ w × N → D ⁡ x = D ⁡ y + ˙ D ⁡ z
13 mdetuni.sc ⊢ φ → ∀ x ∈ B ∀ y ∈ K ∀ z ∈ B ∀ w ∈ N x ↾ w × N = w × N × y · ˙ f z ↾ w × N ∧ x ↾ N ∖ w × N = z ↾ N ∖ w × N → D ⁡ x = y · ˙ D ⁡ z
14 mdetunilem8.id ⊢ φ → D ⁡ 1 A = 0 ˙
15 simpl ⊢ φ ∧ E : N ⟶ 1-1 N → φ
16 enrefg ⊢ N ∈ Fin → N ≈ N
17 8 16 syl ⊢ φ → N ≈ N
18 f1finf1o ⊢ N ≈ N ∧ N ∈ Fin → E : N ⟶ 1-1 N ↔ E : N ⟶ 1-1 onto N
19 17 8 18 syl2anc ⊢ φ → E : N ⟶ 1-1 N ↔ E : N ⟶ 1-1 onto N
20 19 biimpa ⊢ φ ∧ E : N ⟶ 1-1 N → E : N ⟶ 1-1 onto N
21 1 matring ⊢ N ∈ Fin ∧ R ∈ Ring → A ∈ Ring
22 8 9 21 syl2anc ⊢ φ → A ∈ Ring
23 eqid ⊢ 1 A = 1 A
24 2 23 ringidcl ⊢ A ∈ Ring → 1 A ∈ B
25 22 24 syl ⊢ φ → 1 A ∈ B
26 25 adantr ⊢ φ ∧ E : N ⟶ 1-1 N → 1 A ∈ B
27 1 2 3 4 5 6 7 8 9 10 11 12 13 mdetunilem7 ⊢ φ ∧ E : N ⟶ 1-1 onto N ∧ 1 A ∈ B → D ⁡ a ∈ N , b ∈ N ⟼ E ⁡ a 1 A b = ℤRHom ⁡ R ∘ pmSgn ⁡ N ⁡ E · ˙ D ⁡ 1 A
28 15 20 26 27 syl3anc ⊢ φ ∧ E : N ⟶ 1-1 N → D ⁡ a ∈ N , b ∈ N ⟼ E ⁡ a 1 A b = ℤRHom ⁡ R ∘ pmSgn ⁡ N ⁡ E · ˙ D ⁡ 1 A
29 8 adantr ⊢ φ ∧ E : N ⟶ 1-1 N → N ∈ Fin
30 29 3ad2ant1 ⊢ φ ∧ E : N ⟶ 1-1 N ∧ a ∈ N ∧ b ∈ N → N ∈ Fin
31 9 adantr ⊢ φ ∧ E : N ⟶ 1-1 N → R ∈ Ring
32 31 3ad2ant1 ⊢ φ ∧ E : N ⟶ 1-1 N ∧ a ∈ N ∧ b ∈ N → R ∈ Ring
33 simp1r ⊢ φ ∧ E : N ⟶ 1-1 N ∧ a ∈ N ∧ b ∈ N → E : N ⟶ 1-1 N
34 f1f ⊢ E : N ⟶ 1-1 N → E : N ⟶ N
35 33 34 syl ⊢ φ ∧ E : N ⟶ 1-1 N ∧ a ∈ N ∧ b ∈ N → E : N ⟶ N
36 simp2 ⊢ φ ∧ E : N ⟶ 1-1 N ∧ a ∈ N ∧ b ∈ N → a ∈ N
37 35 36 ffvelcdmd ⊢ φ ∧ E : N ⟶ 1-1 N ∧ a ∈ N ∧ b ∈ N → E ⁡ a ∈ N
38 simp3 ⊢ φ ∧ E : N ⟶ 1-1 N ∧ a ∈ N ∧ b ∈ N → b ∈ N
39 1 5 4 30 32 37 38 23 mat1ov ⊢ φ ∧ E : N ⟶ 1-1 N ∧ a ∈ N ∧ b ∈ N → E ⁡ a 1 A b = if E ⁡ a = b 1 ˙ 0 ˙
40 39 mpoeq3dva ⊢ φ ∧ E : N ⟶ 1-1 N → a ∈ N , b ∈ N ⟼ E ⁡ a 1 A b = a ∈ N , b ∈ N ⟼ if E ⁡ a = b 1 ˙ 0 ˙
41 40 fveq2d ⊢ φ ∧ E : N ⟶ 1-1 N → D ⁡ a ∈ N , b ∈ N ⟼ E ⁡ a 1 A b = D ⁡ a ∈ N , b ∈ N ⟼ if E ⁡ a = b 1 ˙ 0 ˙
42 14 adantr ⊢ φ ∧ E : N ⟶ 1-1 N → D ⁡ 1 A = 0 ˙
43 42 oveq2d ⊢ φ ∧ E : N ⟶ 1-1 N → ℤRHom ⁡ R ∘ pmSgn ⁡ N ⁡ E · ˙ D ⁡ 1 A = ℤRHom ⁡ R ∘ pmSgn ⁡ N ⁡ E · ˙ 0 ˙
44 zrhpsgnmhm ⊢ R ∈ Ring ∧ N ∈ Fin → ℤRHom ⁡ R ∘ pmSgn ⁡ N ∈ SymGrp ⁡ N MndHom mulGrp R
45 9 8 44 syl2anc ⊢ φ → ℤRHom ⁡ R ∘ pmSgn ⁡ N ∈ SymGrp ⁡ N MndHom mulGrp R
46 eqid ⊢ Base SymGrp ⁡ N = Base SymGrp ⁡ N
47 eqid ⊢ mulGrp R = mulGrp R
48 47 3 mgpbas ⊢ K = Base mulGrp R
49 46 48 mhmf ⊢ ℤRHom ⁡ R ∘ pmSgn ⁡ N ∈ SymGrp ⁡ N MndHom mulGrp R → ℤRHom ⁡ R ∘ pmSgn ⁡ N : Base SymGrp ⁡ N ⟶ K
50 45 49 syl ⊢ φ → ℤRHom ⁡ R ∘ pmSgn ⁡ N : Base SymGrp ⁡ N ⟶ K
51 50 adantr ⊢ φ ∧ E : N ⟶ 1-1 N → ℤRHom ⁡ R ∘ pmSgn ⁡ N : Base SymGrp ⁡ N ⟶ K
52 eqid ⊢ SymGrp ⁡ N = SymGrp ⁡ N
53 52 46 elsymgbas ⊢ N ∈ Fin → E ∈ Base SymGrp ⁡ N ↔ E : N ⟶ 1-1 onto N
54 29 53 syl ⊢ φ ∧ E : N ⟶ 1-1 N → E ∈ Base SymGrp ⁡ N ↔ E : N ⟶ 1-1 onto N
55 20 54 mpbird ⊢ φ ∧ E : N ⟶ 1-1 N → E ∈ Base SymGrp ⁡ N
56 51 55 ffvelcdmd ⊢ φ ∧ E : N ⟶ 1-1 N → ℤRHom ⁡ R ∘ pmSgn ⁡ N ⁡ E ∈ K
57 3 7 4 ringrz ⊢ R ∈ Ring ∧ ℤRHom ⁡ R ∘ pmSgn ⁡ N ⁡ E ∈ K → ℤRHom ⁡ R ∘ pmSgn ⁡ N ⁡ E · ˙ 0 ˙ = 0 ˙
58 31 56 57 syl2anc ⊢ φ ∧ E : N ⟶ 1-1 N → ℤRHom ⁡ R ∘ pmSgn ⁡ N ⁡ E · ˙ 0 ˙ = 0 ˙
59 43 58 eqtrd ⊢ φ ∧ E : N ⟶ 1-1 N → ℤRHom ⁡ R ∘ pmSgn ⁡ N ⁡ E · ˙ D ⁡ 1 A = 0 ˙
60 28 41 59 3eqtr3d ⊢ φ ∧ E : N ⟶ 1-1 N → D ⁡ a ∈ N , b ∈ N ⟼ if E ⁡ a = b 1 ˙ 0 ˙ = 0 ˙
61 60 ex ⊢ φ → E : N ⟶ 1-1 N → D ⁡ a ∈ N , b ∈ N ⟼ if E ⁡ a = b 1 ˙ 0 ˙ = 0 ˙
62 61 adantr ⊢ φ ∧ E : N ⟶ N → E : N ⟶ 1-1 N → D ⁡ a ∈ N , b ∈ N ⟼ if E ⁡ a = b 1 ˙ 0 ˙ = 0 ˙
63 dff13 ⊢ E : N ⟶ 1-1 N ↔ E : N ⟶ N ∧ ∀ c ∈ N ∀ d ∈ N E ⁡ c = E ⁡ d → c = d
64 ibar ⊢ E : N ⟶ N → ∀ c ∈ N ∀ d ∈ N E ⁡ c = E ⁡ d → c = d ↔ E : N ⟶ N ∧ ∀ c ∈ N ∀ d ∈ N E ⁡ c = E ⁡ d → c = d
65 64 adantl ⊢ φ ∧ E : N ⟶ N → ∀ c ∈ N ∀ d ∈ N E ⁡ c = E ⁡ d → c = d ↔ E : N ⟶ N ∧ ∀ c ∈ N ∀ d ∈ N E ⁡ c = E ⁡ d → c = d
66 63 65 bitr4id ⊢ φ ∧ E : N ⟶ N → E : N ⟶ 1-1 N ↔ ∀ c ∈ N ∀ d ∈ N E ⁡ c = E ⁡ d → c = d
67 66 notbid ⊢ φ ∧ E : N ⟶ N → ¬ E : N ⟶ 1-1 N ↔ ¬ ∀ c ∈ N ∀ d ∈ N E ⁡ c = E ⁡ d → c = d
68 rexnal ⊢ ∃ c ∈ N ¬ ∀ d ∈ N E ⁡ c = E ⁡ d → c = d ↔ ¬ ∀ c ∈ N ∀ d ∈ N E ⁡ c = E ⁡ d → c = d
69 rexnal ⊢ ∃ d ∈ N ¬ E ⁡ c = E ⁡ d → c = d ↔ ¬ ∀ d ∈ N E ⁡ c = E ⁡ d → c = d
70 df-ne ⊢ c ≠ d ↔ ¬ c = d
71 70 anbi2i ⊢ E ⁡ c = E ⁡ d ∧ c ≠ d ↔ E ⁡ c = E ⁡ d ∧ ¬ c = d
72 annim ⊢ E ⁡ c = E ⁡ d ∧ ¬ c = d ↔ ¬ E ⁡ c = E ⁡ d → c = d
73 71 72 bitr2i ⊢ ¬ E ⁡ c = E ⁡ d → c = d ↔ E ⁡ c = E ⁡ d ∧ c ≠ d
74 73 rexbii ⊢ ∃ d ∈ N ¬ E ⁡ c = E ⁡ d → c = d ↔ ∃ d ∈ N E ⁡ c = E ⁡ d ∧ c ≠ d
75 69 74 bitr3i ⊢ ¬ ∀ d ∈ N E ⁡ c = E ⁡ d → c = d ↔ ∃ d ∈ N E ⁡ c = E ⁡ d ∧ c ≠ d
76 75 rexbii ⊢ ∃ c ∈ N ¬ ∀ d ∈ N E ⁡ c = E ⁡ d → c = d ↔ ∃ c ∈ N ∃ d ∈ N E ⁡ c = E ⁡ d ∧ c ≠ d
77 68 76 bitr3i ⊢ ¬ ∀ c ∈ N ∀ d ∈ N E ⁡ c = E ⁡ d → c = d ↔ ∃ c ∈ N ∃ d ∈ N E ⁡ c = E ⁡ d ∧ c ≠ d
78 67 77 bitrdi ⊢ φ ∧ E : N ⟶ N → ¬ E : N ⟶ 1-1 N ↔ ∃ c ∈ N ∃ d ∈ N E ⁡ c = E ⁡ d ∧ c ≠ d
79 simprrl ⊢ φ ∧ E : N ⟶ N ∧ c ∈ N ∧ d ∈ N ∧ E ⁡ c = E ⁡ d ∧ c ≠ d → E ⁡ c = E ⁡ d
80 fveqeq2 ⊢ a = c → E ⁡ a = b ↔ E ⁡ c = b
81 80 ifbid ⊢ a = c → if E ⁡ a = b 1 ˙ 0 ˙ = if E ⁡ c = b 1 ˙ 0 ˙
82 iftrue ⊢ a = c → if a = c if E ⁡ c = b 1 ˙ 0 ˙ if a = d if E ⁡ d = b 1 ˙ 0 ˙ if E ⁡ a = b 1 ˙ 0 ˙ = if E ⁡ c = b 1 ˙ 0 ˙
83 81 82 eqtr4d ⊢ a = c → if E ⁡ a = b 1 ˙ 0 ˙ = if a = c if E ⁡ c = b 1 ˙ 0 ˙ if a = d if E ⁡ d = b 1 ˙ 0 ˙ if E ⁡ a = b 1 ˙ 0 ˙
84 fveqeq2 ⊢ a = d → E ⁡ a = b ↔ E ⁡ d = b
85 84 ifbid ⊢ a = d → if E ⁡ a = b 1 ˙ 0 ˙ = if E ⁡ d = b 1 ˙ 0 ˙
86 iftrue ⊢ a = d → if a = d if E ⁡ d = b 1 ˙ 0 ˙ if E ⁡ a = b 1 ˙ 0 ˙ = if E ⁡ d = b 1 ˙ 0 ˙
87 85 86 eqtr4d ⊢ a = d → if E ⁡ a = b 1 ˙ 0 ˙ = if a = d if E ⁡ d = b 1 ˙ 0 ˙ if E ⁡ a = b 1 ˙ 0 ˙
88 iffalse ⊢ ¬ a = d → if a = d if E ⁡ d = b 1 ˙ 0 ˙ if E ⁡ a = b 1 ˙ 0 ˙ = if E ⁡ a = b 1 ˙ 0 ˙
89 88 eqcomd ⊢ ¬ a = d → if E ⁡ a = b 1 ˙ 0 ˙ = if a = d if E ⁡ d = b 1 ˙ 0 ˙ if E ⁡ a = b 1 ˙ 0 ˙
90 87 89 pm2.61i ⊢ if E ⁡ a = b 1 ˙ 0 ˙ = if a = d if E ⁡ d = b 1 ˙ 0 ˙ if E ⁡ a = b 1 ˙ 0 ˙
91 iffalse ⊢ ¬ a = c → if a = c if E ⁡ c = b 1 ˙ 0 ˙ if a = d if E ⁡ d = b 1 ˙ 0 ˙ if E ⁡ a = b 1 ˙ 0 ˙ = if a = d if E ⁡ d = b 1 ˙ 0 ˙ if E ⁡ a = b 1 ˙ 0 ˙
92 90 91 eqtr4id ⊢ ¬ a = c → if E ⁡ a = b 1 ˙ 0 ˙ = if a = c if E ⁡ c = b 1 ˙ 0 ˙ if a = d if E ⁡ d = b 1 ˙ 0 ˙ if E ⁡ a = b 1 ˙ 0 ˙
93 83 92 pm2.61i ⊢ if E ⁡ a = b 1 ˙ 0 ˙ = if a = c if E ⁡ c = b 1 ˙ 0 ˙ if a = d if E ⁡ d = b 1 ˙ 0 ˙ if E ⁡ a = b 1 ˙ 0 ˙
94 eqeq1 ⊢ E ⁡ d = E ⁡ c → E ⁡ d = b ↔ E ⁡ c = b
95 94 eqcoms ⊢ E ⁡ c = E ⁡ d → E ⁡ d = b ↔ E ⁡ c = b
96 95 ifbid ⊢ E ⁡ c = E ⁡ d → if E ⁡ d = b 1 ˙ 0 ˙ = if E ⁡ c = b 1 ˙ 0 ˙
97 96 ifeq1d ⊢ E ⁡ c = E ⁡ d → if a = d if E ⁡ d = b 1 ˙ 0 ˙ if E ⁡ a = b 1 ˙ 0 ˙ = if a = d if E ⁡ c = b 1 ˙ 0 ˙ if E ⁡ a = b 1 ˙ 0 ˙
98 97 ifeq2d ⊢ E ⁡ c = E ⁡ d → if a = c if E ⁡ c = b 1 ˙ 0 ˙ if a = d if E ⁡ d = b 1 ˙ 0 ˙ if E ⁡ a = b 1 ˙ 0 ˙ = if a = c if E ⁡ c = b 1 ˙ 0 ˙ if a = d if E ⁡ c = b 1 ˙ 0 ˙ if E ⁡ a = b 1 ˙ 0 ˙
99 93 98 eqtrid ⊢ E ⁡ c = E ⁡ d → if E ⁡ a = b 1 ˙ 0 ˙ = if a = c if E ⁡ c = b 1 ˙ 0 ˙ if a = d if E ⁡ c = b 1 ˙ 0 ˙ if E ⁡ a = b 1 ˙ 0 ˙
100 99 mpoeq3dv ⊢ E ⁡ c = E ⁡ d → a ∈ N , b ∈ N ⟼ if E ⁡ a = b 1 ˙ 0 ˙ = a ∈ N , b ∈ N ⟼ if a = c if E ⁡ c = b 1 ˙ 0 ˙ if a = d if E ⁡ c = b 1 ˙ 0 ˙ if E ⁡ a = b 1 ˙ 0 ˙
101 100 fveq2d ⊢ E ⁡ c = E ⁡ d → D ⁡ a ∈ N , b ∈ N ⟼ if E ⁡ a = b 1 ˙ 0 ˙ = D ⁡ a ∈ N , b ∈ N ⟼ if a = c if E ⁡ c = b 1 ˙ 0 ˙ if a = d if E ⁡ c = b 1 ˙ 0 ˙ if E ⁡ a = b 1 ˙ 0 ˙
102 79 101 syl ⊢ φ ∧ E : N ⟶ N ∧ c ∈ N ∧ d ∈ N ∧ E ⁡ c = E ⁡ d ∧ c ≠ d → D ⁡ a ∈ N , b ∈ N ⟼ if E ⁡ a = b 1 ˙ 0 ˙ = D ⁡ a ∈ N , b ∈ N ⟼ if a = c if E ⁡ c = b 1 ˙ 0 ˙ if a = d if E ⁡ c = b 1 ˙ 0 ˙ if E ⁡ a = b 1 ˙ 0 ˙
103 simpll ⊢ φ ∧ E : N ⟶ N ∧ c ∈ N ∧ d ∈ N ∧ E ⁡ c = E ⁡ d ∧ c ≠ d → φ
104 simprll ⊢ φ ∧ E : N ⟶ N ∧ c ∈ N ∧ d ∈ N ∧ E ⁡ c = E ⁡ d ∧ c ≠ d → c ∈ N
105 simprlr ⊢ φ ∧ E : N ⟶ N ∧ c ∈ N ∧ d ∈ N ∧ E ⁡ c = E ⁡ d ∧ c ≠ d → d ∈ N
106 simprrr ⊢ φ ∧ E : N ⟶ N ∧ c ∈ N ∧ d ∈ N ∧ E ⁡ c = E ⁡ d ∧ c ≠ d → c ≠ d
107 104 105 106 3jca ⊢ φ ∧ E : N ⟶ N ∧ c ∈ N ∧ d ∈ N ∧ E ⁡ c = E ⁡ d ∧ c ≠ d → c ∈ N ∧ d ∈ N ∧ c ≠ d
108 3 5 ringidcl ⊢ R ∈ Ring → 1 ˙ ∈ K
109 9 108 syl ⊢ φ → 1 ˙ ∈ K
110 3 4 ring0cl ⊢ R ∈ Ring → 0 ˙ ∈ K
111 9 110 syl ⊢ φ → 0 ˙ ∈ K
112 109 111 ifcld ⊢ φ → if E ⁡ c = b 1 ˙ 0 ˙ ∈ K
113 112 ad3antrrr ⊢ φ ∧ E : N ⟶ N ∧ c ∈ N ∧ d ∈ N ∧ E ⁡ c = E ⁡ d ∧ c ≠ d ∧ b ∈ N → if E ⁡ c = b 1 ˙ 0 ˙ ∈ K
114 simp1ll ⊢ φ ∧ E : N ⟶ N ∧ c ∈ N ∧ d ∈ N ∧ E ⁡ c = E ⁡ d ∧ c ≠ d ∧ a ∈ N ∧ b ∈ N → φ
115 109 111 ifcld ⊢ φ → if E ⁡ a = b 1 ˙ 0 ˙ ∈ K
116 114 115 syl ⊢ φ ∧ E : N ⟶ N ∧ c ∈ N ∧ d ∈ N ∧ E ⁡ c = E ⁡ d ∧ c ≠ d ∧ a ∈ N ∧ b ∈ N → if E ⁡ a = b 1 ˙ 0 ˙ ∈ K
117 1 2 3 4 5 6 7 8 9 10 11 12 13 103 107 113 116 mdetunilem2 ⊢ φ ∧ E : N ⟶ N ∧ c ∈ N ∧ d ∈ N ∧ E ⁡ c = E ⁡ d ∧ c ≠ d → D ⁡ a ∈ N , b ∈ N ⟼ if a = c if E ⁡ c = b 1 ˙ 0 ˙ if a = d if E ⁡ c = b 1 ˙ 0 ˙ if E ⁡ a = b 1 ˙ 0 ˙ = 0 ˙
118 102 117 eqtrd ⊢ φ ∧ E : N ⟶ N ∧ c ∈ N ∧ d ∈ N ∧ E ⁡ c = E ⁡ d ∧ c ≠ d → D ⁡ a ∈ N , b ∈ N ⟼ if E ⁡ a = b 1 ˙ 0 ˙ = 0 ˙
119 118 expr ⊢ φ ∧ E : N ⟶ N ∧ c ∈ N ∧ d ∈ N → E ⁡ c = E ⁡ d ∧ c ≠ d → D ⁡ a ∈ N , b ∈ N ⟼ if E ⁡ a = b 1 ˙ 0 ˙ = 0 ˙
120 119 rexlimdvva ⊢ φ ∧ E : N ⟶ N → ∃ c ∈ N ∃ d ∈ N E ⁡ c = E ⁡ d ∧ c ≠ d → D ⁡ a ∈ N , b ∈ N ⟼ if E ⁡ a = b 1 ˙ 0 ˙ = 0 ˙
121 78 120 sylbid ⊢ φ ∧ E : N ⟶ N → ¬ E : N ⟶ 1-1 N → D ⁡ a ∈ N , b ∈ N ⟼ if E ⁡ a = b 1 ˙ 0 ˙ = 0 ˙
122 62 121 pm2.61d ⊢ φ ∧ E : N ⟶ N → D ⁡ a ∈ N , b ∈ N ⟼ if E ⁡ a = b 1 ˙ 0 ˙ = 0 ˙