Step | Hyp | Ref
| Expression |
1 | | ovex 7288 |
. . 3
⊢ (𝐴 mod 8) ∈
V |
2 | 1 | elpr 4581 |
. 2
⊢ ((𝐴 mod 8) ∈ {1, 7} ↔
((𝐴 mod 8) = 1 ∨ (𝐴 mod 8) = 7)) |
3 | | zre 12253 |
. . . . . . 7
⊢ (𝐴 ∈ ℤ → 𝐴 ∈
ℝ) |
4 | 3 | ad2antrr 722 |
. . . . . 6
⊢ (((𝐴 ∈ ℤ ∧ 𝐵 ∈ ℤ) ∧ (𝐴 mod 8) = 1) → 𝐴 ∈
ℝ) |
5 | | 1red 10907 |
. . . . . 6
⊢ (((𝐴 ∈ ℤ ∧ 𝐵 ∈ ℤ) ∧ (𝐴 mod 8) = 1) → 1 ∈
ℝ) |
6 | | simplr 765 |
. . . . . 6
⊢ (((𝐴 ∈ ℤ ∧ 𝐵 ∈ ℤ) ∧ (𝐴 mod 8) = 1) → 𝐵 ∈
ℤ) |
7 | | 8re 11999 |
. . . . . . . 8
⊢ 8 ∈
ℝ |
8 | | 8pos 12015 |
. . . . . . . 8
⊢ 0 <
8 |
9 | 7, 8 | elrpii 12662 |
. . . . . . 7
⊢ 8 ∈
ℝ+ |
10 | 9 | a1i 11 |
. . . . . 6
⊢ (((𝐴 ∈ ℤ ∧ 𝐵 ∈ ℤ) ∧ (𝐴 mod 8) = 1) → 8 ∈
ℝ+) |
11 | | simpr 484 |
. . . . . . 7
⊢ (((𝐴 ∈ ℤ ∧ 𝐵 ∈ ℤ) ∧ (𝐴 mod 8) = 1) → (𝐴 mod 8) = 1) |
12 | | lgsdir2lem1 26378 |
. . . . . . . . 9
⊢ (((1 mod
8) = 1 ∧ (-1 mod 8) = 7) ∧ ((3 mod 8) = 3 ∧ (-3 mod 8) =
5)) |
13 | 12 | simpli 483 |
. . . . . . . 8
⊢ ((1 mod
8) = 1 ∧ (-1 mod 8) = 7) |
14 | 13 | simpli 483 |
. . . . . . 7
⊢ (1 mod 8)
= 1 |
15 | 11, 14 | eqtr4di 2797 |
. . . . . 6
⊢ (((𝐴 ∈ ℤ ∧ 𝐵 ∈ ℤ) ∧ (𝐴 mod 8) = 1) → (𝐴 mod 8) = (1 mod
8)) |
16 | | modmul1 13572 |
. . . . . 6
⊢ (((𝐴 ∈ ℝ ∧ 1 ∈
ℝ) ∧ (𝐵 ∈
ℤ ∧ 8 ∈ ℝ+) ∧ (𝐴 mod 8) = (1 mod 8)) → ((𝐴 · 𝐵) mod 8) = ((1 · 𝐵) mod 8)) |
17 | 4, 5, 6, 10, 15, 16 | syl221anc 1379 |
. . . . 5
⊢ (((𝐴 ∈ ℤ ∧ 𝐵 ∈ ℤ) ∧ (𝐴 mod 8) = 1) → ((𝐴 · 𝐵) mod 8) = ((1 · 𝐵) mod 8)) |
18 | | zcn 12254 |
. . . . . . . 8
⊢ (𝐵 ∈ ℤ → 𝐵 ∈
ℂ) |
19 | 18 | ad2antlr 723 |
. . . . . . 7
⊢ (((𝐴 ∈ ℤ ∧ 𝐵 ∈ ℤ) ∧ (𝐴 mod 8) = 1) → 𝐵 ∈
ℂ) |
20 | 19 | mulid2d 10924 |
. . . . . 6
⊢ (((𝐴 ∈ ℤ ∧ 𝐵 ∈ ℤ) ∧ (𝐴 mod 8) = 1) → (1 ·
𝐵) = 𝐵) |
21 | 20 | oveq1d 7270 |
. . . . 5
⊢ (((𝐴 ∈ ℤ ∧ 𝐵 ∈ ℤ) ∧ (𝐴 mod 8) = 1) → ((1 ·
𝐵) mod 8) = (𝐵 mod 8)) |
22 | 17, 21 | eqtrd 2778 |
. . . 4
⊢ (((𝐴 ∈ ℤ ∧ 𝐵 ∈ ℤ) ∧ (𝐴 mod 8) = 1) → ((𝐴 · 𝐵) mod 8) = (𝐵 mod 8)) |
23 | 22 | eleq1d 2823 |
. . 3
⊢ (((𝐴 ∈ ℤ ∧ 𝐵 ∈ ℤ) ∧ (𝐴 mod 8) = 1) → (((𝐴 · 𝐵) mod 8) ∈ {1, 7} ↔ (𝐵 mod 8) ∈ {1,
7})) |
24 | 3 | ad2antrr 722 |
. . . . . . 7
⊢ (((𝐴 ∈ ℤ ∧ 𝐵 ∈ ℤ) ∧ (𝐴 mod 8) = 7) → 𝐴 ∈
ℝ) |
25 | | neg1rr 12018 |
. . . . . . . 8
⊢ -1 ∈
ℝ |
26 | 25 | a1i 11 |
. . . . . . 7
⊢ (((𝐴 ∈ ℤ ∧ 𝐵 ∈ ℤ) ∧ (𝐴 mod 8) = 7) → -1 ∈
ℝ) |
27 | | simplr 765 |
. . . . . . 7
⊢ (((𝐴 ∈ ℤ ∧ 𝐵 ∈ ℤ) ∧ (𝐴 mod 8) = 7) → 𝐵 ∈
ℤ) |
28 | 9 | a1i 11 |
. . . . . . 7
⊢ (((𝐴 ∈ ℤ ∧ 𝐵 ∈ ℤ) ∧ (𝐴 mod 8) = 7) → 8 ∈
ℝ+) |
29 | | simpr 484 |
. . . . . . . 8
⊢ (((𝐴 ∈ ℤ ∧ 𝐵 ∈ ℤ) ∧ (𝐴 mod 8) = 7) → (𝐴 mod 8) = 7) |
30 | 13 | simpri 485 |
. . . . . . . 8
⊢ (-1 mod
8) = 7 |
31 | 29, 30 | eqtr4di 2797 |
. . . . . . 7
⊢ (((𝐴 ∈ ℤ ∧ 𝐵 ∈ ℤ) ∧ (𝐴 mod 8) = 7) → (𝐴 mod 8) = (-1 mod
8)) |
32 | | modmul1 13572 |
. . . . . . 7
⊢ (((𝐴 ∈ ℝ ∧ -1 ∈
ℝ) ∧ (𝐵 ∈
ℤ ∧ 8 ∈ ℝ+) ∧ (𝐴 mod 8) = (-1 mod 8)) → ((𝐴 · 𝐵) mod 8) = ((-1 · 𝐵) mod 8)) |
33 | 24, 26, 27, 28, 31, 32 | syl221anc 1379 |
. . . . . 6
⊢ (((𝐴 ∈ ℤ ∧ 𝐵 ∈ ℤ) ∧ (𝐴 mod 8) = 7) → ((𝐴 · 𝐵) mod 8) = ((-1 · 𝐵) mod 8)) |
34 | 18 | ad2antlr 723 |
. . . . . . . 8
⊢ (((𝐴 ∈ ℤ ∧ 𝐵 ∈ ℤ) ∧ (𝐴 mod 8) = 7) → 𝐵 ∈
ℂ) |
35 | 34 | mulm1d 11357 |
. . . . . . 7
⊢ (((𝐴 ∈ ℤ ∧ 𝐵 ∈ ℤ) ∧ (𝐴 mod 8) = 7) → (-1 ·
𝐵) = -𝐵) |
36 | 35 | oveq1d 7270 |
. . . . . 6
⊢ (((𝐴 ∈ ℤ ∧ 𝐵 ∈ ℤ) ∧ (𝐴 mod 8) = 7) → ((-1
· 𝐵) mod 8) =
(-𝐵 mod
8)) |
37 | 33, 36 | eqtrd 2778 |
. . . . 5
⊢ (((𝐴 ∈ ℤ ∧ 𝐵 ∈ ℤ) ∧ (𝐴 mod 8) = 7) → ((𝐴 · 𝐵) mod 8) = (-𝐵 mod 8)) |
38 | 37 | eleq1d 2823 |
. . . 4
⊢ (((𝐴 ∈ ℤ ∧ 𝐵 ∈ ℤ) ∧ (𝐴 mod 8) = 7) → (((𝐴 · 𝐵) mod 8) ∈ {1, 7} ↔ (-𝐵 mod 8) ∈ {1,
7})) |
39 | | znegcl 12285 |
. . . . . . . 8
⊢ (𝐵 ∈ ℤ → -𝐵 ∈
ℤ) |
40 | | oveq1 7262 |
. . . . . . . . . . 11
⊢ (𝑥 = -𝐵 → (𝑥 mod 8) = (-𝐵 mod 8)) |
41 | 40 | eleq1d 2823 |
. . . . . . . . . 10
⊢ (𝑥 = -𝐵 → ((𝑥 mod 8) ∈ {1, 7} ↔ (-𝐵 mod 8) ∈ {1,
7})) |
42 | | negeq 11143 |
. . . . . . . . . . . 12
⊢ (𝑥 = -𝐵 → -𝑥 = --𝐵) |
43 | 42 | oveq1d 7270 |
. . . . . . . . . . 11
⊢ (𝑥 = -𝐵 → (-𝑥 mod 8) = (--𝐵 mod 8)) |
44 | 43 | eleq1d 2823 |
. . . . . . . . . 10
⊢ (𝑥 = -𝐵 → ((-𝑥 mod 8) ∈ {1, 7} ↔ (--𝐵 mod 8) ∈ {1,
7})) |
45 | 41, 44 | imbi12d 344 |
. . . . . . . . 9
⊢ (𝑥 = -𝐵 → (((𝑥 mod 8) ∈ {1, 7} → (-𝑥 mod 8) ∈ {1, 7}) ↔
((-𝐵 mod 8) ∈ {1, 7}
→ (--𝐵 mod 8) ∈
{1, 7}))) |
46 | | zcn 12254 |
. . . . . . . . . . . . . . . . 17
⊢ (𝑥 ∈ ℤ → 𝑥 ∈
ℂ) |
47 | | neg1cn 12017 |
. . . . . . . . . . . . . . . . . . 19
⊢ -1 ∈
ℂ |
48 | | mulcom 10888 |
. . . . . . . . . . . . . . . . . . 19
⊢ ((𝑥 ∈ ℂ ∧ -1 ∈
ℂ) → (𝑥 ·
-1) = (-1 · 𝑥)) |
49 | 47, 48 | mpan2 687 |
. . . . . . . . . . . . . . . . . 18
⊢ (𝑥 ∈ ℂ → (𝑥 · -1) = (-1 ·
𝑥)) |
50 | | mulm1 11346 |
. . . . . . . . . . . . . . . . . 18
⊢ (𝑥 ∈ ℂ → (-1
· 𝑥) = -𝑥) |
51 | 49, 50 | eqtrd 2778 |
. . . . . . . . . . . . . . . . 17
⊢ (𝑥 ∈ ℂ → (𝑥 · -1) = -𝑥) |
52 | 46, 51 | syl 17 |
. . . . . . . . . . . . . . . 16
⊢ (𝑥 ∈ ℤ → (𝑥 · -1) = -𝑥) |
53 | 52 | adantr 480 |
. . . . . . . . . . . . . . 15
⊢ ((𝑥 ∈ ℤ ∧ (𝑥 mod 8) = 1) → (𝑥 · -1) = -𝑥) |
54 | 53 | oveq1d 7270 |
. . . . . . . . . . . . . 14
⊢ ((𝑥 ∈ ℤ ∧ (𝑥 mod 8) = 1) → ((𝑥 · -1) mod 8) = (-𝑥 mod 8)) |
55 | | zre 12253 |
. . . . . . . . . . . . . . . 16
⊢ (𝑥 ∈ ℤ → 𝑥 ∈
ℝ) |
56 | 55 | adantr 480 |
. . . . . . . . . . . . . . 15
⊢ ((𝑥 ∈ ℤ ∧ (𝑥 mod 8) = 1) → 𝑥 ∈
ℝ) |
57 | | 1red 10907 |
. . . . . . . . . . . . . . 15
⊢ ((𝑥 ∈ ℤ ∧ (𝑥 mod 8) = 1) → 1 ∈
ℝ) |
58 | | neg1z 12286 |
. . . . . . . . . . . . . . . 16
⊢ -1 ∈
ℤ |
59 | 58 | a1i 11 |
. . . . . . . . . . . . . . 15
⊢ ((𝑥 ∈ ℤ ∧ (𝑥 mod 8) = 1) → -1 ∈
ℤ) |
60 | 9 | a1i 11 |
. . . . . . . . . . . . . . 15
⊢ ((𝑥 ∈ ℤ ∧ (𝑥 mod 8) = 1) → 8 ∈
ℝ+) |
61 | | simpr 484 |
. . . . . . . . . . . . . . . 16
⊢ ((𝑥 ∈ ℤ ∧ (𝑥 mod 8) = 1) → (𝑥 mod 8) = 1) |
62 | 61, 14 | eqtr4di 2797 |
. . . . . . . . . . . . . . 15
⊢ ((𝑥 ∈ ℤ ∧ (𝑥 mod 8) = 1) → (𝑥 mod 8) = (1 mod
8)) |
63 | | modmul1 13572 |
. . . . . . . . . . . . . . 15
⊢ (((𝑥 ∈ ℝ ∧ 1 ∈
ℝ) ∧ (-1 ∈ ℤ ∧ 8 ∈ ℝ+) ∧
(𝑥 mod 8) = (1 mod 8))
→ ((𝑥 · -1) mod
8) = ((1 · -1) mod 8)) |
64 | 56, 57, 59, 60, 62, 63 | syl221anc 1379 |
. . . . . . . . . . . . . 14
⊢ ((𝑥 ∈ ℤ ∧ (𝑥 mod 8) = 1) → ((𝑥 · -1) mod 8) = ((1
· -1) mod 8)) |
65 | 54, 64 | eqtr3d 2780 |
. . . . . . . . . . . . 13
⊢ ((𝑥 ∈ ℤ ∧ (𝑥 mod 8) = 1) → (-𝑥 mod 8) = ((1 · -1) mod
8)) |
66 | 47 | mulid2i 10911 |
. . . . . . . . . . . . . . 15
⊢ (1
· -1) = -1 |
67 | 66 | oveq1i 7265 |
. . . . . . . . . . . . . 14
⊢ ((1
· -1) mod 8) = (-1 mod 8) |
68 | 67, 30 | eqtri 2766 |
. . . . . . . . . . . . 13
⊢ ((1
· -1) mod 8) = 7 |
69 | 65, 68 | eqtrdi 2795 |
. . . . . . . . . . . 12
⊢ ((𝑥 ∈ ℤ ∧ (𝑥 mod 8) = 1) → (-𝑥 mod 8) = 7) |
70 | 69 | ex 412 |
. . . . . . . . . . 11
⊢ (𝑥 ∈ ℤ → ((𝑥 mod 8) = 1 → (-𝑥 mod 8) = 7)) |
71 | 52 | adantr 480 |
. . . . . . . . . . . . . . 15
⊢ ((𝑥 ∈ ℤ ∧ (𝑥 mod 8) = 7) → (𝑥 · -1) = -𝑥) |
72 | 71 | oveq1d 7270 |
. . . . . . . . . . . . . 14
⊢ ((𝑥 ∈ ℤ ∧ (𝑥 mod 8) = 7) → ((𝑥 · -1) mod 8) = (-𝑥 mod 8)) |
73 | 55 | adantr 480 |
. . . . . . . . . . . . . . 15
⊢ ((𝑥 ∈ ℤ ∧ (𝑥 mod 8) = 7) → 𝑥 ∈
ℝ) |
74 | 25 | a1i 11 |
. . . . . . . . . . . . . . 15
⊢ ((𝑥 ∈ ℤ ∧ (𝑥 mod 8) = 7) → -1 ∈
ℝ) |
75 | 58 | a1i 11 |
. . . . . . . . . . . . . . 15
⊢ ((𝑥 ∈ ℤ ∧ (𝑥 mod 8) = 7) → -1 ∈
ℤ) |
76 | 9 | a1i 11 |
. . . . . . . . . . . . . . 15
⊢ ((𝑥 ∈ ℤ ∧ (𝑥 mod 8) = 7) → 8 ∈
ℝ+) |
77 | | simpr 484 |
. . . . . . . . . . . . . . . 16
⊢ ((𝑥 ∈ ℤ ∧ (𝑥 mod 8) = 7) → (𝑥 mod 8) = 7) |
78 | 77, 30 | eqtr4di 2797 |
. . . . . . . . . . . . . . 15
⊢ ((𝑥 ∈ ℤ ∧ (𝑥 mod 8) = 7) → (𝑥 mod 8) = (-1 mod
8)) |
79 | | modmul1 13572 |
. . . . . . . . . . . . . . 15
⊢ (((𝑥 ∈ ℝ ∧ -1 ∈
ℝ) ∧ (-1 ∈ ℤ ∧ 8 ∈ ℝ+) ∧
(𝑥 mod 8) = (-1 mod 8))
→ ((𝑥 · -1) mod
8) = ((-1 · -1) mod 8)) |
80 | 73, 74, 75, 76, 78, 79 | syl221anc 1379 |
. . . . . . . . . . . . . 14
⊢ ((𝑥 ∈ ℤ ∧ (𝑥 mod 8) = 7) → ((𝑥 · -1) mod 8) = ((-1
· -1) mod 8)) |
81 | 72, 80 | eqtr3d 2780 |
. . . . . . . . . . . . 13
⊢ ((𝑥 ∈ ℤ ∧ (𝑥 mod 8) = 7) → (-𝑥 mod 8) = ((-1 · -1) mod
8)) |
82 | | neg1mulneg1e1 12116 |
. . . . . . . . . . . . . . 15
⊢ (-1
· -1) = 1 |
83 | 82 | oveq1i 7265 |
. . . . . . . . . . . . . 14
⊢ ((-1
· -1) mod 8) = (1 mod 8) |
84 | 83, 14 | eqtri 2766 |
. . . . . . . . . . . . 13
⊢ ((-1
· -1) mod 8) = 1 |
85 | 81, 84 | eqtrdi 2795 |
. . . . . . . . . . . 12
⊢ ((𝑥 ∈ ℤ ∧ (𝑥 mod 8) = 7) → (-𝑥 mod 8) = 1) |
86 | 85 | ex 412 |
. . . . . . . . . . 11
⊢ (𝑥 ∈ ℤ → ((𝑥 mod 8) = 7 → (-𝑥 mod 8) = 1)) |
87 | 70, 86 | orim12d 961 |
. . . . . . . . . 10
⊢ (𝑥 ∈ ℤ → (((𝑥 mod 8) = 1 ∨ (𝑥 mod 8) = 7) → ((-𝑥 mod 8) = 7 ∨ (-𝑥 mod 8) = 1))) |
88 | | ovex 7288 |
. . . . . . . . . . 11
⊢ (𝑥 mod 8) ∈
V |
89 | 88 | elpr 4581 |
. . . . . . . . . 10
⊢ ((𝑥 mod 8) ∈ {1, 7} ↔
((𝑥 mod 8) = 1 ∨ (𝑥 mod 8) = 7)) |
90 | | ovex 7288 |
. . . . . . . . . . . 12
⊢ (-𝑥 mod 8) ∈
V |
91 | 90 | elpr 4581 |
. . . . . . . . . . 11
⊢ ((-𝑥 mod 8) ∈ {1, 7} ↔
((-𝑥 mod 8) = 1 ∨
(-𝑥 mod 8) =
7)) |
92 | | orcom 866 |
. . . . . . . . . . 11
⊢ (((-𝑥 mod 8) = 1 ∨ (-𝑥 mod 8) = 7) ↔ ((-𝑥 mod 8) = 7 ∨ (-𝑥 mod 8) = 1)) |
93 | 91, 92 | bitri 274 |
. . . . . . . . . 10
⊢ ((-𝑥 mod 8) ∈ {1, 7} ↔
((-𝑥 mod 8) = 7 ∨
(-𝑥 mod 8) =
1)) |
94 | 87, 89, 93 | 3imtr4g 295 |
. . . . . . . . 9
⊢ (𝑥 ∈ ℤ → ((𝑥 mod 8) ∈ {1, 7} →
(-𝑥 mod 8) ∈ {1,
7})) |
95 | 45, 94 | vtoclga 3503 |
. . . . . . . 8
⊢ (-𝐵 ∈ ℤ → ((-𝐵 mod 8) ∈ {1, 7} →
(--𝐵 mod 8) ∈ {1,
7})) |
96 | 39, 95 | syl 17 |
. . . . . . 7
⊢ (𝐵 ∈ ℤ → ((-𝐵 mod 8) ∈ {1, 7} →
(--𝐵 mod 8) ∈ {1,
7})) |
97 | 18 | negnegd 11253 |
. . . . . . . . 9
⊢ (𝐵 ∈ ℤ → --𝐵 = 𝐵) |
98 | 97 | oveq1d 7270 |
. . . . . . . 8
⊢ (𝐵 ∈ ℤ → (--𝐵 mod 8) = (𝐵 mod 8)) |
99 | 98 | eleq1d 2823 |
. . . . . . 7
⊢ (𝐵 ∈ ℤ → ((--𝐵 mod 8) ∈ {1, 7} ↔
(𝐵 mod 8) ∈ {1,
7})) |
100 | 96, 99 | sylibd 238 |
. . . . . 6
⊢ (𝐵 ∈ ℤ → ((-𝐵 mod 8) ∈ {1, 7} →
(𝐵 mod 8) ∈ {1,
7})) |
101 | | oveq1 7262 |
. . . . . . . . 9
⊢ (𝑥 = 𝐵 → (𝑥 mod 8) = (𝐵 mod 8)) |
102 | 101 | eleq1d 2823 |
. . . . . . . 8
⊢ (𝑥 = 𝐵 → ((𝑥 mod 8) ∈ {1, 7} ↔ (𝐵 mod 8) ∈ {1,
7})) |
103 | | negeq 11143 |
. . . . . . . . . 10
⊢ (𝑥 = 𝐵 → -𝑥 = -𝐵) |
104 | 103 | oveq1d 7270 |
. . . . . . . . 9
⊢ (𝑥 = 𝐵 → (-𝑥 mod 8) = (-𝐵 mod 8)) |
105 | 104 | eleq1d 2823 |
. . . . . . . 8
⊢ (𝑥 = 𝐵 → ((-𝑥 mod 8) ∈ {1, 7} ↔ (-𝐵 mod 8) ∈ {1,
7})) |
106 | 102, 105 | imbi12d 344 |
. . . . . . 7
⊢ (𝑥 = 𝐵 → (((𝑥 mod 8) ∈ {1, 7} → (-𝑥 mod 8) ∈ {1, 7}) ↔
((𝐵 mod 8) ∈ {1, 7}
→ (-𝐵 mod 8) ∈
{1, 7}))) |
107 | 106, 94 | vtoclga 3503 |
. . . . . 6
⊢ (𝐵 ∈ ℤ → ((𝐵 mod 8) ∈ {1, 7} →
(-𝐵 mod 8) ∈ {1,
7})) |
108 | 100, 107 | impbid 211 |
. . . . 5
⊢ (𝐵 ∈ ℤ → ((-𝐵 mod 8) ∈ {1, 7} ↔
(𝐵 mod 8) ∈ {1,
7})) |
109 | 108 | ad2antlr 723 |
. . . 4
⊢ (((𝐴 ∈ ℤ ∧ 𝐵 ∈ ℤ) ∧ (𝐴 mod 8) = 7) → ((-𝐵 mod 8) ∈ {1, 7} ↔
(𝐵 mod 8) ∈ {1,
7})) |
110 | 38, 109 | bitrd 278 |
. . 3
⊢ (((𝐴 ∈ ℤ ∧ 𝐵 ∈ ℤ) ∧ (𝐴 mod 8) = 7) → (((𝐴 · 𝐵) mod 8) ∈ {1, 7} ↔ (𝐵 mod 8) ∈ {1,
7})) |
111 | 23, 110 | jaodan 954 |
. 2
⊢ (((𝐴 ∈ ℤ ∧ 𝐵 ∈ ℤ) ∧ ((𝐴 mod 8) = 1 ∨ (𝐴 mod 8) = 7)) → (((𝐴 · 𝐵) mod 8) ∈ {1, 7} ↔ (𝐵 mod 8) ∈ {1,
7})) |
112 | 2, 111 | sylan2b 593 |
1
⊢ (((𝐴 ∈ ℤ ∧ 𝐵 ∈ ℤ) ∧ (𝐴 mod 8) ∈ {1, 7}) →
(((𝐴 · 𝐵) mod 8) ∈ {1, 7} ↔
(𝐵 mod 8) ∈ {1,
7})) |