Proof of Theorem signswch
Step | Hyp | Ref
| Expression |
1 | | df-pr 4569 |
. . . . . 6
⊢ {-1, 1} =
({-1} ∪ {1}) |
2 | | snsstp1 4754 |
. . . . . . 7
⊢ {-1}
⊆ {-1, 0, 1} |
3 | | snsstp3 4756 |
. . . . . . 7
⊢ {1}
⊆ {-1, 0, 1} |
4 | 2, 3 | unssi 4123 |
. . . . . 6
⊢ ({-1}
∪ {1}) ⊆ {-1, 0, 1} |
5 | 1, 4 | eqsstri 3959 |
. . . . 5
⊢ {-1, 1}
⊆ {-1, 0, 1} |
6 | 5 | sseli 3921 |
. . . 4
⊢ (𝑋 ∈ {-1, 1} → 𝑋 ∈ {-1, 0,
1}) |
7 | | signsw.p |
. . . . 5
⊢ ⨣ =
(𝑎 ∈ {-1, 0, 1}, 𝑏 ∈ {-1, 0, 1} ↦
if(𝑏 = 0, 𝑎, 𝑏)) |
8 | 7 | signspval 32510 |
. . . 4
⊢ ((𝑋 ∈ {-1, 0, 1} ∧ 𝑌 ∈ {-1, 0, 1}) →
(𝑋 ⨣ 𝑌) = if(𝑌 = 0, 𝑋, 𝑌)) |
9 | 6, 8 | sylan 579 |
. . 3
⊢ ((𝑋 ∈ {-1, 1} ∧ 𝑌 ∈ {-1, 0, 1}) →
(𝑋 ⨣ 𝑌) = if(𝑌 = 0, 𝑋, 𝑌)) |
10 | 9 | neeq1d 3004 |
. 2
⊢ ((𝑋 ∈ {-1, 1} ∧ 𝑌 ∈ {-1, 0, 1}) →
((𝑋 ⨣ 𝑌) ≠ 𝑋 ↔ if(𝑌 = 0, 𝑋, 𝑌) ≠ 𝑋)) |
11 | | neeq1 3007 |
. . . 4
⊢ (𝑋 = if(𝑌 = 0, 𝑋, 𝑌) → (𝑋 ≠ 𝑋 ↔ if(𝑌 = 0, 𝑋, 𝑌) ≠ 𝑋)) |
12 | 11 | bibi1d 343 |
. . 3
⊢ (𝑋 = if(𝑌 = 0, 𝑋, 𝑌) → ((𝑋 ≠ 𝑋 ↔ (𝑋 · 𝑌) < 0) ↔ (if(𝑌 = 0, 𝑋, 𝑌) ≠ 𝑋 ↔ (𝑋 · 𝑌) < 0))) |
13 | | neeq1 3007 |
. . . 4
⊢ (𝑌 = if(𝑌 = 0, 𝑋, 𝑌) → (𝑌 ≠ 𝑋 ↔ if(𝑌 = 0, 𝑋, 𝑌) ≠ 𝑋)) |
14 | 13 | bibi1d 343 |
. . 3
⊢ (𝑌 = if(𝑌 = 0, 𝑋, 𝑌) → ((𝑌 ≠ 𝑋 ↔ (𝑋 · 𝑌) < 0) ↔ (if(𝑌 = 0, 𝑋, 𝑌) ≠ 𝑋 ↔ (𝑋 · 𝑌) < 0))) |
15 | | neirr 2953 |
. . . . 5
⊢ ¬
𝑋 ≠ 𝑋 |
16 | 15 | a1i 11 |
. . . 4
⊢ (((𝑋 ∈ {-1, 1} ∧ 𝑌 ∈ {-1, 0, 1}) ∧ 𝑌 = 0) → ¬ 𝑋 ≠ 𝑋) |
17 | | 0re 10961 |
. . . . . 6
⊢ 0 ∈
ℝ |
18 | 17 | ltnri 11067 |
. . . . 5
⊢ ¬ 0
< 0 |
19 | | simpr 484 |
. . . . . . . 8
⊢ (((𝑋 ∈ {-1, 1} ∧ 𝑌 ∈ {-1, 0, 1}) ∧ 𝑌 = 0) → 𝑌 = 0) |
20 | 19 | oveq2d 7284 |
. . . . . . 7
⊢ (((𝑋 ∈ {-1, 1} ∧ 𝑌 ∈ {-1, 0, 1}) ∧ 𝑌 = 0) → (𝑋 · 𝑌) = (𝑋 · 0)) |
21 | | neg1cn 12070 |
. . . . . . . . . 10
⊢ -1 ∈
ℂ |
22 | | ax-1cn 10913 |
. . . . . . . . . 10
⊢ 1 ∈
ℂ |
23 | | prssi 4759 |
. . . . . . . . . 10
⊢ ((-1
∈ ℂ ∧ 1 ∈ ℂ) → {-1, 1} ⊆
ℂ) |
24 | 21, 22, 23 | mp2an 688 |
. . . . . . . . 9
⊢ {-1, 1}
⊆ ℂ |
25 | | simpll 763 |
. . . . . . . . 9
⊢ (((𝑋 ∈ {-1, 1} ∧ 𝑌 ∈ {-1, 0, 1}) ∧ 𝑌 = 0) → 𝑋 ∈ {-1, 1}) |
26 | 24, 25 | sselid 3923 |
. . . . . . . 8
⊢ (((𝑋 ∈ {-1, 1} ∧ 𝑌 ∈ {-1, 0, 1}) ∧ 𝑌 = 0) → 𝑋 ∈ ℂ) |
27 | 26 | mul01d 11157 |
. . . . . . 7
⊢ (((𝑋 ∈ {-1, 1} ∧ 𝑌 ∈ {-1, 0, 1}) ∧ 𝑌 = 0) → (𝑋 · 0) = 0) |
28 | 20, 27 | eqtrd 2779 |
. . . . . 6
⊢ (((𝑋 ∈ {-1, 1} ∧ 𝑌 ∈ {-1, 0, 1}) ∧ 𝑌 = 0) → (𝑋 · 𝑌) = 0) |
29 | 28 | breq1d 5088 |
. . . . 5
⊢ (((𝑋 ∈ {-1, 1} ∧ 𝑌 ∈ {-1, 0, 1}) ∧ 𝑌 = 0) → ((𝑋 · 𝑌) < 0 ↔ 0 < 0)) |
30 | 18, 29 | mtbiri 326 |
. . . 4
⊢ (((𝑋 ∈ {-1, 1} ∧ 𝑌 ∈ {-1, 0, 1}) ∧ 𝑌 = 0) → ¬ (𝑋 · 𝑌) < 0) |
31 | 16, 30 | 2falsed 376 |
. . 3
⊢ (((𝑋 ∈ {-1, 1} ∧ 𝑌 ∈ {-1, 0, 1}) ∧ 𝑌 = 0) → (𝑋 ≠ 𝑋 ↔ (𝑋 · 𝑌) < 0)) |
32 | | simplr 765 |
. . . . . . . 8
⊢ (((𝑋 ∈ {-1, 1} ∧ 𝑌 ∈ {-1, 0, 1}) ∧ ¬
𝑌 = 0) → 𝑌 ∈ {-1, 0,
1}) |
33 | | tpcomb 4692 |
. . . . . . . 8
⊢ {-1, 0,
1} = {-1, 1, 0} |
34 | 32, 33 | eleqtrdi 2850 |
. . . . . . 7
⊢ (((𝑋 ∈ {-1, 1} ∧ 𝑌 ∈ {-1, 0, 1}) ∧ ¬
𝑌 = 0) → 𝑌 ∈ {-1, 1,
0}) |
35 | | simpr 484 |
. . . . . . . 8
⊢ (((𝑋 ∈ {-1, 1} ∧ 𝑌 ∈ {-1, 0, 1}) ∧ ¬
𝑌 = 0) → ¬ 𝑌 = 0) |
36 | 35 | neqned 2951 |
. . . . . . 7
⊢ (((𝑋 ∈ {-1, 1} ∧ 𝑌 ∈ {-1, 0, 1}) ∧ ¬
𝑌 = 0) → 𝑌 ≠ 0) |
37 | 34, 36 | jca 511 |
. . . . . 6
⊢ (((𝑋 ∈ {-1, 1} ∧ 𝑌 ∈ {-1, 0, 1}) ∧ ¬
𝑌 = 0) → (𝑌 ∈ {-1, 1, 0} ∧ 𝑌 ≠ 0)) |
38 | | eldifsn 4725 |
. . . . . . 7
⊢ (𝑌 ∈ ({-1, 1, 0} ∖ {0})
↔ (𝑌 ∈ {-1, 1, 0}
∧ 𝑌 ≠
0)) |
39 | | neg1ne0 12072 |
. . . . . . . . 9
⊢ -1 ≠
0 |
40 | | ax-1ne0 10924 |
. . . . . . . . 9
⊢ 1 ≠
0 |
41 | | diftpsn3 4740 |
. . . . . . . . 9
⊢ ((-1 ≠
0 ∧ 1 ≠ 0) → ({-1, 1, 0} ∖ {0}) = {-1, 1}) |
42 | 39, 40, 41 | mp2an 688 |
. . . . . . . 8
⊢ ({-1, 1,
0} ∖ {0}) = {-1, 1} |
43 | 42 | eleq2i 2831 |
. . . . . . 7
⊢ (𝑌 ∈ ({-1, 1, 0} ∖ {0})
↔ 𝑌 ∈ {-1,
1}) |
44 | 38, 43 | bitr3i 276 |
. . . . . 6
⊢ ((𝑌 ∈ {-1, 1, 0} ∧ 𝑌 ≠ 0) ↔ 𝑌 ∈ {-1,
1}) |
45 | 37, 44 | sylib 217 |
. . . . 5
⊢ (((𝑋 ∈ {-1, 1} ∧ 𝑌 ∈ {-1, 0, 1}) ∧ ¬
𝑌 = 0) → 𝑌 ∈ {-1,
1}) |
46 | | neirr 2953 |
. . . . . . . . . . 11
⊢ ¬ -1
≠ -1 |
47 | | 0le1 11481 |
. . . . . . . . . . . . 13
⊢ 0 ≤
1 |
48 | | 1re 10959 |
. . . . . . . . . . . . . 14
⊢ 1 ∈
ℝ |
49 | 17, 48 | lenlti 11078 |
. . . . . . . . . . . . 13
⊢ (0 ≤ 1
↔ ¬ 1 < 0) |
50 | 47, 49 | mpbi 229 |
. . . . . . . . . . . 12
⊢ ¬ 1
< 0 |
51 | | neg1mulneg1e1 12169 |
. . . . . . . . . . . . 13
⊢ (-1
· -1) = 1 |
52 | 51 | breq1i 5085 |
. . . . . . . . . . . 12
⊢ ((-1
· -1) < 0 ↔ 1 < 0) |
53 | 50, 52 | mtbir 322 |
. . . . . . . . . . 11
⊢ ¬
(-1 · -1) < 0 |
54 | 46, 53 | 2false 375 |
. . . . . . . . . 10
⊢ (-1 ≠
-1 ↔ (-1 · -1) < 0) |
55 | | neeq1 3007 |
. . . . . . . . . . 11
⊢ (𝑌 = -1 → (𝑌 ≠ -1 ↔ -1 ≠
-1)) |
56 | | oveq2 7276 |
. . . . . . . . . . . 12
⊢ (𝑌 = -1 → (-1 · 𝑌) = (-1 ·
-1)) |
57 | 56 | breq1d 5088 |
. . . . . . . . . . 11
⊢ (𝑌 = -1 → ((-1 · 𝑌) < 0 ↔ (-1 · -1)
< 0)) |
58 | 55, 57 | bibi12d 345 |
. . . . . . . . . 10
⊢ (𝑌 = -1 → ((𝑌 ≠ -1 ↔ (-1 · 𝑌) < 0) ↔ (-1 ≠ -1
↔ (-1 · -1) < 0))) |
59 | 54, 58 | mpbiri 257 |
. . . . . . . . 9
⊢ (𝑌 = -1 → (𝑌 ≠ -1 ↔ (-1 · 𝑌) < 0)) |
60 | 59 | adantl 481 |
. . . . . . . 8
⊢ ((𝑌 ∈ {-1, 1} ∧ 𝑌 = -1) → (𝑌 ≠ -1 ↔ (-1 · 𝑌) < 0)) |
61 | | neg1rr 12071 |
. . . . . . . . . . . 12
⊢ -1 ∈
ℝ |
62 | | neg1lt0 12073 |
. . . . . . . . . . . . 13
⊢ -1 <
0 |
63 | | 0lt1 11480 |
. . . . . . . . . . . . 13
⊢ 0 <
1 |
64 | 61, 17, 48 | lttri 11084 |
. . . . . . . . . . . . 13
⊢ ((-1 <
0 ∧ 0 < 1) → -1 < 1) |
65 | 62, 63, 64 | mp2an 688 |
. . . . . . . . . . . 12
⊢ -1 <
1 |
66 | 61, 65 | gtneii 11070 |
. . . . . . . . . . 11
⊢ 1 ≠
-1 |
67 | 21 | mulid1i 10963 |
. . . . . . . . . . . 12
⊢ (-1
· 1) = -1 |
68 | 67, 62 | eqbrtri 5099 |
. . . . . . . . . . 11
⊢ (-1
· 1) < 0 |
69 | 66, 68 | 2th 263 |
. . . . . . . . . 10
⊢ (1 ≠
-1 ↔ (-1 · 1) < 0) |
70 | | neeq1 3007 |
. . . . . . . . . . 11
⊢ (𝑌 = 1 → (𝑌 ≠ -1 ↔ 1 ≠ -1)) |
71 | | oveq2 7276 |
. . . . . . . . . . . 12
⊢ (𝑌 = 1 → (-1 · 𝑌) = (-1 ·
1)) |
72 | 71 | breq1d 5088 |
. . . . . . . . . . 11
⊢ (𝑌 = 1 → ((-1 · 𝑌) < 0 ↔ (-1 · 1)
< 0)) |
73 | 70, 72 | bibi12d 345 |
. . . . . . . . . 10
⊢ (𝑌 = 1 → ((𝑌 ≠ -1 ↔ (-1 · 𝑌) < 0) ↔ (1 ≠ -1
↔ (-1 · 1) < 0))) |
74 | 69, 73 | mpbiri 257 |
. . . . . . . . 9
⊢ (𝑌 = 1 → (𝑌 ≠ -1 ↔ (-1 · 𝑌) < 0)) |
75 | 74 | adantl 481 |
. . . . . . . 8
⊢ ((𝑌 ∈ {-1, 1} ∧ 𝑌 = 1) → (𝑌 ≠ -1 ↔ (-1 · 𝑌) < 0)) |
76 | | elpri 4588 |
. . . . . . . 8
⊢ (𝑌 ∈ {-1, 1} → (𝑌 = -1 ∨ 𝑌 = 1)) |
77 | 60, 75, 76 | mpjaodan 955 |
. . . . . . 7
⊢ (𝑌 ∈ {-1, 1} → (𝑌 ≠ -1 ↔ (-1 ·
𝑌) <
0)) |
78 | 77 | adantr 480 |
. . . . . 6
⊢ ((𝑌 ∈ {-1, 1} ∧ 𝑋 = -1) → (𝑌 ≠ -1 ↔ (-1 · 𝑌) < 0)) |
79 | | neeq2 3008 |
. . . . . . . 8
⊢ (𝑋 = -1 → (𝑌 ≠ 𝑋 ↔ 𝑌 ≠ -1)) |
80 | | oveq1 7275 |
. . . . . . . . 9
⊢ (𝑋 = -1 → (𝑋 · 𝑌) = (-1 · 𝑌)) |
81 | 80 | breq1d 5088 |
. . . . . . . 8
⊢ (𝑋 = -1 → ((𝑋 · 𝑌) < 0 ↔ (-1 · 𝑌) < 0)) |
82 | 79, 81 | bibi12d 345 |
. . . . . . 7
⊢ (𝑋 = -1 → ((𝑌 ≠ 𝑋 ↔ (𝑋 · 𝑌) < 0) ↔ (𝑌 ≠ -1 ↔ (-1 · 𝑌) < 0))) |
83 | 82 | adantl 481 |
. . . . . 6
⊢ ((𝑌 ∈ {-1, 1} ∧ 𝑋 = -1) → ((𝑌 ≠ 𝑋 ↔ (𝑋 · 𝑌) < 0) ↔ (𝑌 ≠ -1 ↔ (-1 · 𝑌) < 0))) |
84 | 78, 83 | mpbird 256 |
. . . . 5
⊢ ((𝑌 ∈ {-1, 1} ∧ 𝑋 = -1) → (𝑌 ≠ 𝑋 ↔ (𝑋 · 𝑌) < 0)) |
85 | 45, 84 | sylan 579 |
. . . 4
⊢ ((((𝑋 ∈ {-1, 1} ∧ 𝑌 ∈ {-1, 0, 1}) ∧ ¬
𝑌 = 0) ∧ 𝑋 = -1) → (𝑌 ≠ 𝑋 ↔ (𝑋 · 𝑌) < 0)) |
86 | 66 | necomi 2999 |
. . . . . . . . . . 11
⊢ -1 ≠
1 |
87 | 21, 22 | mulcomi 10967 |
. . . . . . . . . . . . 13
⊢ (-1
· 1) = (1 · -1) |
88 | 87 | breq1i 5085 |
. . . . . . . . . . . 12
⊢ ((-1
· 1) < 0 ↔ (1 · -1) < 0) |
89 | 68, 88 | mpbi 229 |
. . . . . . . . . . 11
⊢ (1
· -1) < 0 |
90 | 86, 89 | 2th 263 |
. . . . . . . . . 10
⊢ (-1 ≠
1 ↔ (1 · -1) < 0) |
91 | | neeq1 3007 |
. . . . . . . . . . 11
⊢ (𝑌 = -1 → (𝑌 ≠ 1 ↔ -1 ≠ 1)) |
92 | | oveq2 7276 |
. . . . . . . . . . . 12
⊢ (𝑌 = -1 → (1 · 𝑌) = (1 ·
-1)) |
93 | 92 | breq1d 5088 |
. . . . . . . . . . 11
⊢ (𝑌 = -1 → ((1 · 𝑌) < 0 ↔ (1 · -1)
< 0)) |
94 | 91, 93 | bibi12d 345 |
. . . . . . . . . 10
⊢ (𝑌 = -1 → ((𝑌 ≠ 1 ↔ (1 · 𝑌) < 0) ↔ (-1 ≠ 1 ↔ (1
· -1) < 0))) |
95 | 90, 94 | mpbiri 257 |
. . . . . . . . 9
⊢ (𝑌 = -1 → (𝑌 ≠ 1 ↔ (1 · 𝑌) < 0)) |
96 | 95 | adantl 481 |
. . . . . . . 8
⊢ ((𝑌 ∈ {-1, 1} ∧ 𝑌 = -1) → (𝑌 ≠ 1 ↔ (1 · 𝑌) < 0)) |
97 | | neirr 2953 |
. . . . . . . . . . 11
⊢ ¬ 1
≠ 1 |
98 | 22 | mulid1i 10963 |
. . . . . . . . . . . . 13
⊢ (1
· 1) = 1 |
99 | 98 | breq1i 5085 |
. . . . . . . . . . . 12
⊢ ((1
· 1) < 0 ↔ 1 < 0) |
100 | 50, 99 | mtbir 322 |
. . . . . . . . . . 11
⊢ ¬ (1
· 1) < 0 |
101 | 97, 100 | 2false 375 |
. . . . . . . . . 10
⊢ (1 ≠ 1
↔ (1 · 1) < 0) |
102 | | neeq1 3007 |
. . . . . . . . . . 11
⊢ (𝑌 = 1 → (𝑌 ≠ 1 ↔ 1 ≠ 1)) |
103 | | oveq2 7276 |
. . . . . . . . . . . 12
⊢ (𝑌 = 1 → (1 · 𝑌) = (1 ·
1)) |
104 | 103 | breq1d 5088 |
. . . . . . . . . . 11
⊢ (𝑌 = 1 → ((1 · 𝑌) < 0 ↔ (1 · 1)
< 0)) |
105 | 102, 104 | bibi12d 345 |
. . . . . . . . . 10
⊢ (𝑌 = 1 → ((𝑌 ≠ 1 ↔ (1 · 𝑌) < 0) ↔ (1 ≠ 1 ↔ (1
· 1) < 0))) |
106 | 101, 105 | mpbiri 257 |
. . . . . . . . 9
⊢ (𝑌 = 1 → (𝑌 ≠ 1 ↔ (1 · 𝑌) < 0)) |
107 | 106 | adantl 481 |
. . . . . . . 8
⊢ ((𝑌 ∈ {-1, 1} ∧ 𝑌 = 1) → (𝑌 ≠ 1 ↔ (1 · 𝑌) < 0)) |
108 | 96, 107, 76 | mpjaodan 955 |
. . . . . . 7
⊢ (𝑌 ∈ {-1, 1} → (𝑌 ≠ 1 ↔ (1 · 𝑌) < 0)) |
109 | 108 | adantr 480 |
. . . . . 6
⊢ ((𝑌 ∈ {-1, 1} ∧ 𝑋 = 1) → (𝑌 ≠ 1 ↔ (1 · 𝑌) < 0)) |
110 | | neeq2 3008 |
. . . . . . . 8
⊢ (𝑋 = 1 → (𝑌 ≠ 𝑋 ↔ 𝑌 ≠ 1)) |
111 | | oveq1 7275 |
. . . . . . . . 9
⊢ (𝑋 = 1 → (𝑋 · 𝑌) = (1 · 𝑌)) |
112 | 111 | breq1d 5088 |
. . . . . . . 8
⊢ (𝑋 = 1 → ((𝑋 · 𝑌) < 0 ↔ (1 · 𝑌) < 0)) |
113 | 110, 112 | bibi12d 345 |
. . . . . . 7
⊢ (𝑋 = 1 → ((𝑌 ≠ 𝑋 ↔ (𝑋 · 𝑌) < 0) ↔ (𝑌 ≠ 1 ↔ (1 · 𝑌) < 0))) |
114 | 113 | adantl 481 |
. . . . . 6
⊢ ((𝑌 ∈ {-1, 1} ∧ 𝑋 = 1) → ((𝑌 ≠ 𝑋 ↔ (𝑋 · 𝑌) < 0) ↔ (𝑌 ≠ 1 ↔ (1 · 𝑌) < 0))) |
115 | 109, 114 | mpbird 256 |
. . . . 5
⊢ ((𝑌 ∈ {-1, 1} ∧ 𝑋 = 1) → (𝑌 ≠ 𝑋 ↔ (𝑋 · 𝑌) < 0)) |
116 | 45, 115 | sylan 579 |
. . . 4
⊢ ((((𝑋 ∈ {-1, 1} ∧ 𝑌 ∈ {-1, 0, 1}) ∧ ¬
𝑌 = 0) ∧ 𝑋 = 1) → (𝑌 ≠ 𝑋 ↔ (𝑋 · 𝑌) < 0)) |
117 | | elpri 4588 |
. . . . 5
⊢ (𝑋 ∈ {-1, 1} → (𝑋 = -1 ∨ 𝑋 = 1)) |
118 | 117 | ad2antrr 722 |
. . . 4
⊢ (((𝑋 ∈ {-1, 1} ∧ 𝑌 ∈ {-1, 0, 1}) ∧ ¬
𝑌 = 0) → (𝑋 = -1 ∨ 𝑋 = 1)) |
119 | 85, 116, 118 | mpjaodan 955 |
. . 3
⊢ (((𝑋 ∈ {-1, 1} ∧ 𝑌 ∈ {-1, 0, 1}) ∧ ¬
𝑌 = 0) → (𝑌 ≠ 𝑋 ↔ (𝑋 · 𝑌) < 0)) |
120 | 12, 14, 31, 119 | ifbothda 4502 |
. 2
⊢ ((𝑋 ∈ {-1, 1} ∧ 𝑌 ∈ {-1, 0, 1}) →
(if(𝑌 = 0, 𝑋, 𝑌) ≠ 𝑋 ↔ (𝑋 · 𝑌) < 0)) |
121 | 10, 120 | bitrd 278 |
1
⊢ ((𝑋 ∈ {-1, 1} ∧ 𝑌 ∈ {-1, 0, 1}) →
((𝑋 ⨣ 𝑌) ≠ 𝑋 ↔ (𝑋 · 𝑌) < 0)) |