Metamath Proof Explorer


Theorem vietadeg1

Description: The degree of a product of H of linear polynomials of the form X - Z is H . (Contributed by Thierry Arnoux, 15-Feb-2026)

Ref Expression
Hypotheses vieta.w 𝑊 = ( Poly1𝑅 )
vieta.b 𝐵 = ( Base ‘ 𝑅 )
vieta.3 = ( -g𝑊 )
vieta.m 𝑀 = ( mulGrp ‘ 𝑊 )
vieta.q 𝑄 = ( 𝐼 eval 𝑅 )
vieta.e 𝐸 = ( 𝐼 eSymPoly 𝑅 )
vieta.n 𝑁 = ( invg𝑅 )
vieta.1 1 = ( 1r𝑅 )
vieta.t · = ( .r𝑅 )
vieta.x 𝑋 = ( var1𝑅 )
vieta.a 𝐴 = ( algSc ‘ 𝑊 )
vieta.p = ( .g ‘ ( mulGrp ‘ 𝑅 ) )
vieta.h 𝐻 = ( ♯ ‘ 𝐼 )
vieta.i ( 𝜑𝐼 ∈ Fin )
vieta.r ( 𝜑𝑅 ∈ IDomn )
vieta.z ( 𝜑𝑍 : 𝐼𝐵 )
vieta.f 𝐹 = ( 𝑀 Σg ( 𝑛𝐼 ↦ ( 𝑋 ( 𝐴 ‘ ( 𝑍𝑛 ) ) ) ) )
vietadeg1.1 𝐷 = ( deg1𝑅 )
Assertion vietadeg1 ( 𝜑 → ( 𝐷𝐹 ) = 𝐻 )

Proof

Step Hyp Ref Expression
1 vieta.w 𝑊 = ( Poly1𝑅 )
2 vieta.b 𝐵 = ( Base ‘ 𝑅 )
3 vieta.3 = ( -g𝑊 )
4 vieta.m 𝑀 = ( mulGrp ‘ 𝑊 )
5 vieta.q 𝑄 = ( 𝐼 eval 𝑅 )
6 vieta.e 𝐸 = ( 𝐼 eSymPoly 𝑅 )
7 vieta.n 𝑁 = ( invg𝑅 )
8 vieta.1 1 = ( 1r𝑅 )
9 vieta.t · = ( .r𝑅 )
10 vieta.x 𝑋 = ( var1𝑅 )
11 vieta.a 𝐴 = ( algSc ‘ 𝑊 )
12 vieta.p = ( .g ‘ ( mulGrp ‘ 𝑅 ) )
13 vieta.h 𝐻 = ( ♯ ‘ 𝐼 )
14 vieta.i ( 𝜑𝐼 ∈ Fin )
15 vieta.r ( 𝜑𝑅 ∈ IDomn )
16 vieta.z ( 𝜑𝑍 : 𝐼𝐵 )
17 vieta.f 𝐹 = ( 𝑀 Σg ( 𝑛𝐼 ↦ ( 𝑋 ( 𝐴 ‘ ( 𝑍𝑛 ) ) ) ) )
18 vietadeg1.1 𝐷 = ( deg1𝑅 )
19 17 fveq2i ( 𝐷𝐹 ) = ( 𝐷 ‘ ( 𝑀 Σg ( 𝑛𝐼 ↦ ( 𝑋 ( 𝐴 ‘ ( 𝑍𝑛 ) ) ) ) ) )
20 eqid ( Base ‘ 𝑊 ) = ( Base ‘ 𝑊 )
21 eqid ( 0g𝑊 ) = ( 0g𝑊 )
22 15 idomringd ( 𝜑𝑅 ∈ Ring )
23 1 ply1ring ( 𝑅 ∈ Ring → 𝑊 ∈ Ring )
24 ringgrp ( 𝑊 ∈ Ring → 𝑊 ∈ Grp )
25 22 23 24 3syl ( 𝜑𝑊 ∈ Grp )
26 25 adantr ( ( 𝜑𝑛𝐼 ) → 𝑊 ∈ Grp )
27 10 1 20 vr1cl ( 𝑅 ∈ Ring → 𝑋 ∈ ( Base ‘ 𝑊 ) )
28 22 27 syl ( 𝜑𝑋 ∈ ( Base ‘ 𝑊 ) )
29 28 adantr ( ( 𝜑𝑛𝐼 ) → 𝑋 ∈ ( Base ‘ 𝑊 ) )
30 eqid ( Scalar ‘ 𝑊 ) = ( Scalar ‘ 𝑊 )
31 eqid ( Base ‘ ( Scalar ‘ 𝑊 ) ) = ( Base ‘ ( Scalar ‘ 𝑊 ) )
32 15 idomcringd ( 𝜑𝑅 ∈ CRing )
33 1 ply1assa ( 𝑅 ∈ CRing → 𝑊 ∈ AssAlg )
34 32 33 syl ( 𝜑𝑊 ∈ AssAlg )
35 34 adantr ( ( 𝜑𝑛𝐼 ) → 𝑊 ∈ AssAlg )
36 16 ffvelcdmda ( ( 𝜑𝑛𝐼 ) → ( 𝑍𝑛 ) ∈ 𝐵 )
37 1 ply1sca ( 𝑅 ∈ IDomn → 𝑅 = ( Scalar ‘ 𝑊 ) )
38 15 37 syl ( 𝜑𝑅 = ( Scalar ‘ 𝑊 ) )
39 38 fveq2d ( 𝜑 → ( Base ‘ 𝑅 ) = ( Base ‘ ( Scalar ‘ 𝑊 ) ) )
40 2 39 eqtrid ( 𝜑𝐵 = ( Base ‘ ( Scalar ‘ 𝑊 ) ) )
41 40 adantr ( ( 𝜑𝑛𝐼 ) → 𝐵 = ( Base ‘ ( Scalar ‘ 𝑊 ) ) )
42 36 41 eleqtrd ( ( 𝜑𝑛𝐼 ) → ( 𝑍𝑛 ) ∈ ( Base ‘ ( Scalar ‘ 𝑊 ) ) )
43 11 30 31 35 42 asclelbas ( ( 𝜑𝑛𝐼 ) → ( 𝐴 ‘ ( 𝑍𝑛 ) ) ∈ ( Base ‘ 𝑊 ) )
44 20 3 26 29 43 grpsubcld ( ( 𝜑𝑛𝐼 ) → ( 𝑋 ( 𝐴 ‘ ( 𝑍𝑛 ) ) ) ∈ ( Base ‘ 𝑊 ) )
45 15 idomdomd ( 𝜑𝑅 ∈ Domn )
46 domnnzr ( 𝑅 ∈ Domn → 𝑅 ∈ NzRing )
47 45 46 syl ( 𝜑𝑅 ∈ NzRing )
48 18 1 10 47 deg1vr ( 𝜑 → ( 𝐷𝑋 ) = 1 )
49 48 ad2antrr ( ( ( 𝜑𝑛𝐼 ) ∧ ( 𝑋 ( 𝐴 ‘ ( 𝑍𝑛 ) ) ) = ( 0g𝑊 ) ) → ( 𝐷𝑋 ) = 1 )
50 18 1 20 deg1cl ( 𝑋 ∈ ( Base ‘ 𝑊 ) → ( 𝐷𝑋 ) ∈ ( ℕ0 ∪ { -∞ } ) )
51 28 50 syl ( 𝜑 → ( 𝐷𝑋 ) ∈ ( ℕ0 ∪ { -∞ } ) )
52 51 nn0mnfxrd ( 𝜑 → ( 𝐷𝑋 ) ∈ ℝ* )
53 52 ad2antrr ( ( ( 𝜑𝑛𝐼 ) ∧ ( 𝑋 ( 𝐴 ‘ ( 𝑍𝑛 ) ) ) = ( 0g𝑊 ) ) → ( 𝐷𝑋 ) ∈ ℝ* )
54 49 53 eqeltrrd ( ( ( 𝜑𝑛𝐼 ) ∧ ( 𝑋 ( 𝐴 ‘ ( 𝑍𝑛 ) ) ) = ( 0g𝑊 ) ) → 1 ∈ ℝ* )
55 51 ad2antrr ( ( ( 𝜑𝑛𝐼 ) ∧ ( 𝑋 ( 𝐴 ‘ ( 𝑍𝑛 ) ) ) = ( 0g𝑊 ) ) → ( 𝐷𝑋 ) ∈ ( ℕ0 ∪ { -∞ } ) )
56 0zd ( ( ( 𝜑𝑛𝐼 ) ∧ ( 𝑋 ( 𝐴 ‘ ( 𝑍𝑛 ) ) ) = ( 0g𝑊 ) ) → 0 ∈ ℤ )
57 26 adantr ( ( ( 𝜑𝑛𝐼 ) ∧ ( 𝑋 ( 𝐴 ‘ ( 𝑍𝑛 ) ) ) = ( 0g𝑊 ) ) → 𝑊 ∈ Grp )
58 29 adantr ( ( ( 𝜑𝑛𝐼 ) ∧ ( 𝑋 ( 𝐴 ‘ ( 𝑍𝑛 ) ) ) = ( 0g𝑊 ) ) → 𝑋 ∈ ( Base ‘ 𝑊 ) )
59 43 adantr ( ( ( 𝜑𝑛𝐼 ) ∧ ( 𝑋 ( 𝐴 ‘ ( 𝑍𝑛 ) ) ) = ( 0g𝑊 ) ) → ( 𝐴 ‘ ( 𝑍𝑛 ) ) ∈ ( Base ‘ 𝑊 ) )
60 simpr ( ( ( 𝜑𝑛𝐼 ) ∧ ( 𝑋 ( 𝐴 ‘ ( 𝑍𝑛 ) ) ) = ( 0g𝑊 ) ) → ( 𝑋 ( 𝐴 ‘ ( 𝑍𝑛 ) ) ) = ( 0g𝑊 ) )
61 20 21 3 grpsubeq0 ( ( 𝑊 ∈ Grp ∧ 𝑋 ∈ ( Base ‘ 𝑊 ) ∧ ( 𝐴 ‘ ( 𝑍𝑛 ) ) ∈ ( Base ‘ 𝑊 ) ) → ( ( 𝑋 ( 𝐴 ‘ ( 𝑍𝑛 ) ) ) = ( 0g𝑊 ) ↔ 𝑋 = ( 𝐴 ‘ ( 𝑍𝑛 ) ) ) )
62 61 biimpa ( ( ( 𝑊 ∈ Grp ∧ 𝑋 ∈ ( Base ‘ 𝑊 ) ∧ ( 𝐴 ‘ ( 𝑍𝑛 ) ) ∈ ( Base ‘ 𝑊 ) ) ∧ ( 𝑋 ( 𝐴 ‘ ( 𝑍𝑛 ) ) ) = ( 0g𝑊 ) ) → 𝑋 = ( 𝐴 ‘ ( 𝑍𝑛 ) ) )
63 57 58 59 60 62 syl31anc ( ( ( 𝜑𝑛𝐼 ) ∧ ( 𝑋 ( 𝐴 ‘ ( 𝑍𝑛 ) ) ) = ( 0g𝑊 ) ) → 𝑋 = ( 𝐴 ‘ ( 𝑍𝑛 ) ) )
64 63 fveq2d ( ( ( 𝜑𝑛𝐼 ) ∧ ( 𝑋 ( 𝐴 ‘ ( 𝑍𝑛 ) ) ) = ( 0g𝑊 ) ) → ( 𝐷𝑋 ) = ( 𝐷 ‘ ( 𝐴 ‘ ( 𝑍𝑛 ) ) ) )
65 22 adantr ( ( 𝜑𝑛𝐼 ) → 𝑅 ∈ Ring )
66 18 1 2 11 deg1sclle ( ( 𝑅 ∈ Ring ∧ ( 𝑍𝑛 ) ∈ 𝐵 ) → ( 𝐷 ‘ ( 𝐴 ‘ ( 𝑍𝑛 ) ) ) ≤ 0 )
67 65 36 66 syl2anc ( ( 𝜑𝑛𝐼 ) → ( 𝐷 ‘ ( 𝐴 ‘ ( 𝑍𝑛 ) ) ) ≤ 0 )
68 67 adantr ( ( ( 𝜑𝑛𝐼 ) ∧ ( 𝑋 ( 𝐴 ‘ ( 𝑍𝑛 ) ) ) = ( 0g𝑊 ) ) → ( 𝐷 ‘ ( 𝐴 ‘ ( 𝑍𝑛 ) ) ) ≤ 0 )
69 64 68 eqbrtrd ( ( ( 𝜑𝑛𝐼 ) ∧ ( 𝑋 ( 𝐴 ‘ ( 𝑍𝑛 ) ) ) = ( 0g𝑊 ) ) → ( 𝐷𝑋 ) ≤ 0 )
70 degltp1le ( ( ( 𝐷𝑋 ) ∈ ( ℕ0 ∪ { -∞ } ) ∧ 0 ∈ ℤ ) → ( ( 𝐷𝑋 ) < ( 0 + 1 ) ↔ ( 𝐷𝑋 ) ≤ 0 ) )
71 70 biimpar ( ( ( ( 𝐷𝑋 ) ∈ ( ℕ0 ∪ { -∞ } ) ∧ 0 ∈ ℤ ) ∧ ( 𝐷𝑋 ) ≤ 0 ) → ( 𝐷𝑋 ) < ( 0 + 1 ) )
72 55 56 69 71 syl21anc ( ( ( 𝜑𝑛𝐼 ) ∧ ( 𝑋 ( 𝐴 ‘ ( 𝑍𝑛 ) ) ) = ( 0g𝑊 ) ) → ( 𝐷𝑋 ) < ( 0 + 1 ) )
73 0p1e1 ( 0 + 1 ) = 1
74 72 73 breqtrdi ( ( ( 𝜑𝑛𝐼 ) ∧ ( 𝑋 ( 𝐴 ‘ ( 𝑍𝑛 ) ) ) = ( 0g𝑊 ) ) → ( 𝐷𝑋 ) < 1 )
75 53 54 74 xrgtned ( ( ( 𝜑𝑛𝐼 ) ∧ ( 𝑋 ( 𝐴 ‘ ( 𝑍𝑛 ) ) ) = ( 0g𝑊 ) ) → 1 ≠ ( 𝐷𝑋 ) )
76 75 necomd ( ( ( 𝜑𝑛𝐼 ) ∧ ( 𝑋 ( 𝐴 ‘ ( 𝑍𝑛 ) ) ) = ( 0g𝑊 ) ) → ( 𝐷𝑋 ) ≠ 1 )
77 76 neneqd ( ( ( 𝜑𝑛𝐼 ) ∧ ( 𝑋 ( 𝐴 ‘ ( 𝑍𝑛 ) ) ) = ( 0g𝑊 ) ) → ¬ ( 𝐷𝑋 ) = 1 )
78 49 77 pm2.65da ( ( 𝜑𝑛𝐼 ) → ¬ ( 𝑋 ( 𝐴 ‘ ( 𝑍𝑛 ) ) ) = ( 0g𝑊 ) )
79 78 neqned ( ( 𝜑𝑛𝐼 ) → ( 𝑋 ( 𝐴 ‘ ( 𝑍𝑛 ) ) ) ≠ ( 0g𝑊 ) )
80 44 79 eldifsnd ( ( 𝜑𝑛𝐼 ) → ( 𝑋 ( 𝐴 ‘ ( 𝑍𝑛 ) ) ) ∈ ( ( Base ‘ 𝑊 ) ∖ { ( 0g𝑊 ) } ) )
81 80 fmpttd ( 𝜑 → ( 𝑛𝐼 ↦ ( 𝑋 ( 𝐴 ‘ ( 𝑍𝑛 ) ) ) ) : 𝐼 ⟶ ( ( Base ‘ 𝑊 ) ∖ { ( 0g𝑊 ) } ) )
82 18 1 20 4 21 14 15 81 deg1prod ( 𝜑 → ( 𝐷 ‘ ( 𝑀 Σg ( 𝑛𝐼 ↦ ( 𝑋 ( 𝐴 ‘ ( 𝑍𝑛 ) ) ) ) ) ) = Σ 𝑘𝐼 ( 𝐷 ‘ ( ( 𝑛𝐼 ↦ ( 𝑋 ( 𝐴 ‘ ( 𝑍𝑛 ) ) ) ) ‘ 𝑘 ) ) )
83 eqid ( 𝑛𝐼 ↦ ( 𝑋 ( 𝐴 ‘ ( 𝑍𝑛 ) ) ) ) = ( 𝑛𝐼 ↦ ( 𝑋 ( 𝐴 ‘ ( 𝑍𝑛 ) ) ) )
84 2fveq3 ( 𝑛 = 𝑘 → ( 𝐴 ‘ ( 𝑍𝑛 ) ) = ( 𝐴 ‘ ( 𝑍𝑘 ) ) )
85 84 oveq2d ( 𝑛 = 𝑘 → ( 𝑋 ( 𝐴 ‘ ( 𝑍𝑛 ) ) ) = ( 𝑋 ( 𝐴 ‘ ( 𝑍𝑘 ) ) ) )
86 simpr ( ( 𝜑𝑘𝐼 ) → 𝑘𝐼 )
87 ovexd ( ( 𝜑𝑘𝐼 ) → ( 𝑋 ( 𝐴 ‘ ( 𝑍𝑘 ) ) ) ∈ V )
88 83 85 86 87 fvmptd3 ( ( 𝜑𝑘𝐼 ) → ( ( 𝑛𝐼 ↦ ( 𝑋 ( 𝐴 ‘ ( 𝑍𝑛 ) ) ) ) ‘ 𝑘 ) = ( 𝑋 ( 𝐴 ‘ ( 𝑍𝑘 ) ) ) )
89 88 fveq2d ( ( 𝜑𝑘𝐼 ) → ( 𝐷 ‘ ( ( 𝑛𝐼 ↦ ( 𝑋 ( 𝐴 ‘ ( 𝑍𝑛 ) ) ) ) ‘ 𝑘 ) ) = ( 𝐷 ‘ ( 𝑋 ( 𝐴 ‘ ( 𝑍𝑘 ) ) ) ) )
90 18 1 20 deg1xrcl ( ( 𝐴 ‘ ( 𝑍𝑛 ) ) ∈ ( Base ‘ 𝑊 ) → ( 𝐷 ‘ ( 𝐴 ‘ ( 𝑍𝑛 ) ) ) ∈ ℝ* )
91 43 90 syl ( ( 𝜑𝑛𝐼 ) → ( 𝐷 ‘ ( 𝐴 ‘ ( 𝑍𝑛 ) ) ) ∈ ℝ* )
92 0xr 0 ∈ ℝ*
93 92 a1i ( ( 𝜑𝑛𝐼 ) → 0 ∈ ℝ* )
94 1xr 1 ∈ ℝ*
95 94 a1i ( ( 𝜑𝑛𝐼 ) → 1 ∈ ℝ* )
96 0lt1 0 < 1
97 96 a1i ( ( 𝜑𝑛𝐼 ) → 0 < 1 )
98 91 93 95 67 97 xrlelttrd ( ( 𝜑𝑛𝐼 ) → ( 𝐷 ‘ ( 𝐴 ‘ ( 𝑍𝑛 ) ) ) < 1 )
99 48 adantr ( ( 𝜑𝑛𝐼 ) → ( 𝐷𝑋 ) = 1 )
100 98 99 breqtrrd ( ( 𝜑𝑛𝐼 ) → ( 𝐷 ‘ ( 𝐴 ‘ ( 𝑍𝑛 ) ) ) < ( 𝐷𝑋 ) )
101 1 18 65 20 3 29 43 100 deg1sub ( ( 𝜑𝑛𝐼 ) → ( 𝐷 ‘ ( 𝑋 ( 𝐴 ‘ ( 𝑍𝑛 ) ) ) ) = ( 𝐷𝑋 ) )
102 101 99 eqtrd ( ( 𝜑𝑛𝐼 ) → ( 𝐷 ‘ ( 𝑋 ( 𝐴 ‘ ( 𝑍𝑛 ) ) ) ) = 1 )
103 102 ralrimiva ( 𝜑 → ∀ 𝑛𝐼 ( 𝐷 ‘ ( 𝑋 ( 𝐴 ‘ ( 𝑍𝑛 ) ) ) ) = 1 )
104 85 fveqeq2d ( 𝑛 = 𝑘 → ( ( 𝐷 ‘ ( 𝑋 ( 𝐴 ‘ ( 𝑍𝑛 ) ) ) ) = 1 ↔ ( 𝐷 ‘ ( 𝑋 ( 𝐴 ‘ ( 𝑍𝑘 ) ) ) ) = 1 ) )
105 104 cbvralvw ( ∀ 𝑛𝐼 ( 𝐷 ‘ ( 𝑋 ( 𝐴 ‘ ( 𝑍𝑛 ) ) ) ) = 1 ↔ ∀ 𝑘𝐼 ( 𝐷 ‘ ( 𝑋 ( 𝐴 ‘ ( 𝑍𝑘 ) ) ) ) = 1 )
106 103 105 sylib ( 𝜑 → ∀ 𝑘𝐼 ( 𝐷 ‘ ( 𝑋 ( 𝐴 ‘ ( 𝑍𝑘 ) ) ) ) = 1 )
107 106 r19.21bi ( ( 𝜑𝑘𝐼 ) → ( 𝐷 ‘ ( 𝑋 ( 𝐴 ‘ ( 𝑍𝑘 ) ) ) ) = 1 )
108 89 107 eqtrd ( ( 𝜑𝑘𝐼 ) → ( 𝐷 ‘ ( ( 𝑛𝐼 ↦ ( 𝑋 ( 𝐴 ‘ ( 𝑍𝑛 ) ) ) ) ‘ 𝑘 ) ) = 1 )
109 108 sumeq2dv ( 𝜑 → Σ 𝑘𝐼 ( 𝐷 ‘ ( ( 𝑛𝐼 ↦ ( 𝑋 ( 𝐴 ‘ ( 𝑍𝑛 ) ) ) ) ‘ 𝑘 ) ) = Σ 𝑘𝐼 1 )
110 1cnd ( 𝜑 → 1 ∈ ℂ )
111 fsumconst ( ( 𝐼 ∈ Fin ∧ 1 ∈ ℂ ) → Σ 𝑘𝐼 1 = ( ( ♯ ‘ 𝐼 ) · 1 ) )
112 14 110 111 syl2anc ( 𝜑 → Σ 𝑘𝐼 1 = ( ( ♯ ‘ 𝐼 ) · 1 ) )
113 hashcl ( 𝐼 ∈ Fin → ( ♯ ‘ 𝐼 ) ∈ ℕ0 )
114 14 113 syl ( 𝜑 → ( ♯ ‘ 𝐼 ) ∈ ℕ0 )
115 114 nn0cnd ( 𝜑 → ( ♯ ‘ 𝐼 ) ∈ ℂ )
116 115 mulridd ( 𝜑 → ( ( ♯ ‘ 𝐼 ) · 1 ) = ( ♯ ‘ 𝐼 ) )
117 116 13 eqtr4di ( 𝜑 → ( ( ♯ ‘ 𝐼 ) · 1 ) = 𝐻 )
118 109 112 117 3eqtrd ( 𝜑 → Σ 𝑘𝐼 ( 𝐷 ‘ ( ( 𝑛𝐼 ↦ ( 𝑋 ( 𝐴 ‘ ( 𝑍𝑛 ) ) ) ) ‘ 𝑘 ) ) = 𝐻 )
119 82 118 eqtrd ( 𝜑 → ( 𝐷 ‘ ( 𝑀 Σg ( 𝑛𝐼 ↦ ( 𝑋 ( 𝐴 ‘ ( 𝑍𝑛 ) ) ) ) ) ) = 𝐻 )
120 19 119 eqtrid ( 𝜑 → ( 𝐷𝐹 ) = 𝐻 )