Step |
Hyp |
Ref |
Expression |
1 |
|
isgbe |
⊢ ( 𝑁 ∈ GoldbachEven ↔ ( 𝑁 ∈ Even ∧ ∃ 𝑝 ∈ ℙ ∃ 𝑞 ∈ ℙ ( 𝑝 ∈ Odd ∧ 𝑞 ∈ Odd ∧ 𝑁 = ( 𝑝 + 𝑞 ) ) ) ) |
2 |
|
2nn |
⊢ 2 ∈ ℕ |
3 |
2
|
a1i |
⊢ ( ( ( 𝑝 ∈ ℙ ∧ 𝑞 ∈ ℙ ) ∧ ( 𝑝 ∈ Odd ∧ 𝑞 ∈ Odd ∧ 𝑁 = ( 𝑝 + 𝑞 ) ) ) → 2 ∈ ℕ ) |
4 |
|
oveq2 |
⊢ ( 𝑑 = 2 → ( 1 ... 𝑑 ) = ( 1 ... 2 ) ) |
5 |
|
df-2 |
⊢ 2 = ( 1 + 1 ) |
6 |
5
|
oveq2i |
⊢ ( 1 ... 2 ) = ( 1 ... ( 1 + 1 ) ) |
7 |
|
1z |
⊢ 1 ∈ ℤ |
8 |
|
fzpr |
⊢ ( 1 ∈ ℤ → ( 1 ... ( 1 + 1 ) ) = { 1 , ( 1 + 1 ) } ) |
9 |
7 8
|
ax-mp |
⊢ ( 1 ... ( 1 + 1 ) ) = { 1 , ( 1 + 1 ) } |
10 |
|
1p1e2 |
⊢ ( 1 + 1 ) = 2 |
11 |
10
|
preq2i |
⊢ { 1 , ( 1 + 1 ) } = { 1 , 2 } |
12 |
6 9 11
|
3eqtri |
⊢ ( 1 ... 2 ) = { 1 , 2 } |
13 |
4 12
|
eqtrdi |
⊢ ( 𝑑 = 2 → ( 1 ... 𝑑 ) = { 1 , 2 } ) |
14 |
13
|
oveq2d |
⊢ ( 𝑑 = 2 → ( ℙ ↑m ( 1 ... 𝑑 ) ) = ( ℙ ↑m { 1 , 2 } ) ) |
15 |
|
breq1 |
⊢ ( 𝑑 = 2 → ( 𝑑 ≤ 3 ↔ 2 ≤ 3 ) ) |
16 |
13
|
sumeq1d |
⊢ ( 𝑑 = 2 → Σ 𝑘 ∈ ( 1 ... 𝑑 ) ( 𝑓 ‘ 𝑘 ) = Σ 𝑘 ∈ { 1 , 2 } ( 𝑓 ‘ 𝑘 ) ) |
17 |
16
|
eqeq2d |
⊢ ( 𝑑 = 2 → ( 𝑁 = Σ 𝑘 ∈ ( 1 ... 𝑑 ) ( 𝑓 ‘ 𝑘 ) ↔ 𝑁 = Σ 𝑘 ∈ { 1 , 2 } ( 𝑓 ‘ 𝑘 ) ) ) |
18 |
15 17
|
anbi12d |
⊢ ( 𝑑 = 2 → ( ( 𝑑 ≤ 3 ∧ 𝑁 = Σ 𝑘 ∈ ( 1 ... 𝑑 ) ( 𝑓 ‘ 𝑘 ) ) ↔ ( 2 ≤ 3 ∧ 𝑁 = Σ 𝑘 ∈ { 1 , 2 } ( 𝑓 ‘ 𝑘 ) ) ) ) |
19 |
14 18
|
rexeqbidv |
⊢ ( 𝑑 = 2 → ( ∃ 𝑓 ∈ ( ℙ ↑m ( 1 ... 𝑑 ) ) ( 𝑑 ≤ 3 ∧ 𝑁 = Σ 𝑘 ∈ ( 1 ... 𝑑 ) ( 𝑓 ‘ 𝑘 ) ) ↔ ∃ 𝑓 ∈ ( ℙ ↑m { 1 , 2 } ) ( 2 ≤ 3 ∧ 𝑁 = Σ 𝑘 ∈ { 1 , 2 } ( 𝑓 ‘ 𝑘 ) ) ) ) |
20 |
19
|
adantl |
⊢ ( ( ( ( 𝑝 ∈ ℙ ∧ 𝑞 ∈ ℙ ) ∧ ( 𝑝 ∈ Odd ∧ 𝑞 ∈ Odd ∧ 𝑁 = ( 𝑝 + 𝑞 ) ) ) ∧ 𝑑 = 2 ) → ( ∃ 𝑓 ∈ ( ℙ ↑m ( 1 ... 𝑑 ) ) ( 𝑑 ≤ 3 ∧ 𝑁 = Σ 𝑘 ∈ ( 1 ... 𝑑 ) ( 𝑓 ‘ 𝑘 ) ) ↔ ∃ 𝑓 ∈ ( ℙ ↑m { 1 , 2 } ) ( 2 ≤ 3 ∧ 𝑁 = Σ 𝑘 ∈ { 1 , 2 } ( 𝑓 ‘ 𝑘 ) ) ) ) |
21 |
|
1ne2 |
⊢ 1 ≠ 2 |
22 |
|
1ex |
⊢ 1 ∈ V |
23 |
|
2ex |
⊢ 2 ∈ V |
24 |
|
vex |
⊢ 𝑝 ∈ V |
25 |
|
vex |
⊢ 𝑞 ∈ V |
26 |
22 23 24 25
|
fpr |
⊢ ( 1 ≠ 2 → { 〈 1 , 𝑝 〉 , 〈 2 , 𝑞 〉 } : { 1 , 2 } ⟶ { 𝑝 , 𝑞 } ) |
27 |
21 26
|
mp1i |
⊢ ( ( 𝑝 ∈ ℙ ∧ 𝑞 ∈ ℙ ) → { 〈 1 , 𝑝 〉 , 〈 2 , 𝑞 〉 } : { 1 , 2 } ⟶ { 𝑝 , 𝑞 } ) |
28 |
|
prssi |
⊢ ( ( 𝑝 ∈ ℙ ∧ 𝑞 ∈ ℙ ) → { 𝑝 , 𝑞 } ⊆ ℙ ) |
29 |
27 28
|
fssd |
⊢ ( ( 𝑝 ∈ ℙ ∧ 𝑞 ∈ ℙ ) → { 〈 1 , 𝑝 〉 , 〈 2 , 𝑞 〉 } : { 1 , 2 } ⟶ ℙ ) |
30 |
|
prmex |
⊢ ℙ ∈ V |
31 |
|
prex |
⊢ { 1 , 2 } ∈ V |
32 |
30 31
|
pm3.2i |
⊢ ( ℙ ∈ V ∧ { 1 , 2 } ∈ V ) |
33 |
|
elmapg |
⊢ ( ( ℙ ∈ V ∧ { 1 , 2 } ∈ V ) → ( { 〈 1 , 𝑝 〉 , 〈 2 , 𝑞 〉 } ∈ ( ℙ ↑m { 1 , 2 } ) ↔ { 〈 1 , 𝑝 〉 , 〈 2 , 𝑞 〉 } : { 1 , 2 } ⟶ ℙ ) ) |
34 |
32 33
|
mp1i |
⊢ ( ( 𝑝 ∈ ℙ ∧ 𝑞 ∈ ℙ ) → ( { 〈 1 , 𝑝 〉 , 〈 2 , 𝑞 〉 } ∈ ( ℙ ↑m { 1 , 2 } ) ↔ { 〈 1 , 𝑝 〉 , 〈 2 , 𝑞 〉 } : { 1 , 2 } ⟶ ℙ ) ) |
35 |
29 34
|
mpbird |
⊢ ( ( 𝑝 ∈ ℙ ∧ 𝑞 ∈ ℙ ) → { 〈 1 , 𝑝 〉 , 〈 2 , 𝑞 〉 } ∈ ( ℙ ↑m { 1 , 2 } ) ) |
36 |
|
fveq1 |
⊢ ( 𝑓 = { 〈 1 , 𝑝 〉 , 〈 2 , 𝑞 〉 } → ( 𝑓 ‘ 𝑘 ) = ( { 〈 1 , 𝑝 〉 , 〈 2 , 𝑞 〉 } ‘ 𝑘 ) ) |
37 |
36
|
adantr |
⊢ ( ( 𝑓 = { 〈 1 , 𝑝 〉 , 〈 2 , 𝑞 〉 } ∧ 𝑘 ∈ { 1 , 2 } ) → ( 𝑓 ‘ 𝑘 ) = ( { 〈 1 , 𝑝 〉 , 〈 2 , 𝑞 〉 } ‘ 𝑘 ) ) |
38 |
37
|
sumeq2dv |
⊢ ( 𝑓 = { 〈 1 , 𝑝 〉 , 〈 2 , 𝑞 〉 } → Σ 𝑘 ∈ { 1 , 2 } ( 𝑓 ‘ 𝑘 ) = Σ 𝑘 ∈ { 1 , 2 } ( { 〈 1 , 𝑝 〉 , 〈 2 , 𝑞 〉 } ‘ 𝑘 ) ) |
39 |
38
|
eqeq1d |
⊢ ( 𝑓 = { 〈 1 , 𝑝 〉 , 〈 2 , 𝑞 〉 } → ( Σ 𝑘 ∈ { 1 , 2 } ( 𝑓 ‘ 𝑘 ) = ( 𝑝 + 𝑞 ) ↔ Σ 𝑘 ∈ { 1 , 2 } ( { 〈 1 , 𝑝 〉 , 〈 2 , 𝑞 〉 } ‘ 𝑘 ) = ( 𝑝 + 𝑞 ) ) ) |
40 |
39
|
anbi2d |
⊢ ( 𝑓 = { 〈 1 , 𝑝 〉 , 〈 2 , 𝑞 〉 } → ( ( 2 ≤ 3 ∧ Σ 𝑘 ∈ { 1 , 2 } ( 𝑓 ‘ 𝑘 ) = ( 𝑝 + 𝑞 ) ) ↔ ( 2 ≤ 3 ∧ Σ 𝑘 ∈ { 1 , 2 } ( { 〈 1 , 𝑝 〉 , 〈 2 , 𝑞 〉 } ‘ 𝑘 ) = ( 𝑝 + 𝑞 ) ) ) ) |
41 |
40
|
adantl |
⊢ ( ( ( 𝑝 ∈ ℙ ∧ 𝑞 ∈ ℙ ) ∧ 𝑓 = { 〈 1 , 𝑝 〉 , 〈 2 , 𝑞 〉 } ) → ( ( 2 ≤ 3 ∧ Σ 𝑘 ∈ { 1 , 2 } ( 𝑓 ‘ 𝑘 ) = ( 𝑝 + 𝑞 ) ) ↔ ( 2 ≤ 3 ∧ Σ 𝑘 ∈ { 1 , 2 } ( { 〈 1 , 𝑝 〉 , 〈 2 , 𝑞 〉 } ‘ 𝑘 ) = ( 𝑝 + 𝑞 ) ) ) ) |
42 |
|
prmz |
⊢ ( 𝑝 ∈ ℙ → 𝑝 ∈ ℤ ) |
43 |
|
prmz |
⊢ ( 𝑞 ∈ ℙ → 𝑞 ∈ ℤ ) |
44 |
|
fveq2 |
⊢ ( 𝑘 = 1 → ( { 〈 1 , 𝑝 〉 , 〈 2 , 𝑞 〉 } ‘ 𝑘 ) = ( { 〈 1 , 𝑝 〉 , 〈 2 , 𝑞 〉 } ‘ 1 ) ) |
45 |
22 24
|
fvpr1 |
⊢ ( 1 ≠ 2 → ( { 〈 1 , 𝑝 〉 , 〈 2 , 𝑞 〉 } ‘ 1 ) = 𝑝 ) |
46 |
21 45
|
ax-mp |
⊢ ( { 〈 1 , 𝑝 〉 , 〈 2 , 𝑞 〉 } ‘ 1 ) = 𝑝 |
47 |
44 46
|
eqtrdi |
⊢ ( 𝑘 = 1 → ( { 〈 1 , 𝑝 〉 , 〈 2 , 𝑞 〉 } ‘ 𝑘 ) = 𝑝 ) |
48 |
|
fveq2 |
⊢ ( 𝑘 = 2 → ( { 〈 1 , 𝑝 〉 , 〈 2 , 𝑞 〉 } ‘ 𝑘 ) = ( { 〈 1 , 𝑝 〉 , 〈 2 , 𝑞 〉 } ‘ 2 ) ) |
49 |
23 25
|
fvpr2 |
⊢ ( 1 ≠ 2 → ( { 〈 1 , 𝑝 〉 , 〈 2 , 𝑞 〉 } ‘ 2 ) = 𝑞 ) |
50 |
21 49
|
ax-mp |
⊢ ( { 〈 1 , 𝑝 〉 , 〈 2 , 𝑞 〉 } ‘ 2 ) = 𝑞 |
51 |
48 50
|
eqtrdi |
⊢ ( 𝑘 = 2 → ( { 〈 1 , 𝑝 〉 , 〈 2 , 𝑞 〉 } ‘ 𝑘 ) = 𝑞 ) |
52 |
|
zcn |
⊢ ( 𝑝 ∈ ℤ → 𝑝 ∈ ℂ ) |
53 |
|
zcn |
⊢ ( 𝑞 ∈ ℤ → 𝑞 ∈ ℂ ) |
54 |
52 53
|
anim12i |
⊢ ( ( 𝑝 ∈ ℤ ∧ 𝑞 ∈ ℤ ) → ( 𝑝 ∈ ℂ ∧ 𝑞 ∈ ℂ ) ) |
55 |
7 2
|
pm3.2i |
⊢ ( 1 ∈ ℤ ∧ 2 ∈ ℕ ) |
56 |
55
|
a1i |
⊢ ( ( 𝑝 ∈ ℤ ∧ 𝑞 ∈ ℤ ) → ( 1 ∈ ℤ ∧ 2 ∈ ℕ ) ) |
57 |
21
|
a1i |
⊢ ( ( 𝑝 ∈ ℤ ∧ 𝑞 ∈ ℤ ) → 1 ≠ 2 ) |
58 |
47 51 54 56 57
|
sumpr |
⊢ ( ( 𝑝 ∈ ℤ ∧ 𝑞 ∈ ℤ ) → Σ 𝑘 ∈ { 1 , 2 } ( { 〈 1 , 𝑝 〉 , 〈 2 , 𝑞 〉 } ‘ 𝑘 ) = ( 𝑝 + 𝑞 ) ) |
59 |
42 43 58
|
syl2an |
⊢ ( ( 𝑝 ∈ ℙ ∧ 𝑞 ∈ ℙ ) → Σ 𝑘 ∈ { 1 , 2 } ( { 〈 1 , 𝑝 〉 , 〈 2 , 𝑞 〉 } ‘ 𝑘 ) = ( 𝑝 + 𝑞 ) ) |
60 |
|
2re |
⊢ 2 ∈ ℝ |
61 |
|
3re |
⊢ 3 ∈ ℝ |
62 |
|
2lt3 |
⊢ 2 < 3 |
63 |
60 61 62
|
ltleii |
⊢ 2 ≤ 3 |
64 |
59 63
|
jctil |
⊢ ( ( 𝑝 ∈ ℙ ∧ 𝑞 ∈ ℙ ) → ( 2 ≤ 3 ∧ Σ 𝑘 ∈ { 1 , 2 } ( { 〈 1 , 𝑝 〉 , 〈 2 , 𝑞 〉 } ‘ 𝑘 ) = ( 𝑝 + 𝑞 ) ) ) |
65 |
35 41 64
|
rspcedvd |
⊢ ( ( 𝑝 ∈ ℙ ∧ 𝑞 ∈ ℙ ) → ∃ 𝑓 ∈ ( ℙ ↑m { 1 , 2 } ) ( 2 ≤ 3 ∧ Σ 𝑘 ∈ { 1 , 2 } ( 𝑓 ‘ 𝑘 ) = ( 𝑝 + 𝑞 ) ) ) |
66 |
65
|
adantr |
⊢ ( ( ( 𝑝 ∈ ℙ ∧ 𝑞 ∈ ℙ ) ∧ ( 𝑝 ∈ Odd ∧ 𝑞 ∈ Odd ∧ 𝑁 = ( 𝑝 + 𝑞 ) ) ) → ∃ 𝑓 ∈ ( ℙ ↑m { 1 , 2 } ) ( 2 ≤ 3 ∧ Σ 𝑘 ∈ { 1 , 2 } ( 𝑓 ‘ 𝑘 ) = ( 𝑝 + 𝑞 ) ) ) |
67 |
|
eqeq1 |
⊢ ( 𝑁 = ( 𝑝 + 𝑞 ) → ( 𝑁 = Σ 𝑘 ∈ { 1 , 2 } ( 𝑓 ‘ 𝑘 ) ↔ ( 𝑝 + 𝑞 ) = Σ 𝑘 ∈ { 1 , 2 } ( 𝑓 ‘ 𝑘 ) ) ) |
68 |
|
eqcom |
⊢ ( ( 𝑝 + 𝑞 ) = Σ 𝑘 ∈ { 1 , 2 } ( 𝑓 ‘ 𝑘 ) ↔ Σ 𝑘 ∈ { 1 , 2 } ( 𝑓 ‘ 𝑘 ) = ( 𝑝 + 𝑞 ) ) |
69 |
67 68
|
bitrdi |
⊢ ( 𝑁 = ( 𝑝 + 𝑞 ) → ( 𝑁 = Σ 𝑘 ∈ { 1 , 2 } ( 𝑓 ‘ 𝑘 ) ↔ Σ 𝑘 ∈ { 1 , 2 } ( 𝑓 ‘ 𝑘 ) = ( 𝑝 + 𝑞 ) ) ) |
70 |
69
|
anbi2d |
⊢ ( 𝑁 = ( 𝑝 + 𝑞 ) → ( ( 2 ≤ 3 ∧ 𝑁 = Σ 𝑘 ∈ { 1 , 2 } ( 𝑓 ‘ 𝑘 ) ) ↔ ( 2 ≤ 3 ∧ Σ 𝑘 ∈ { 1 , 2 } ( 𝑓 ‘ 𝑘 ) = ( 𝑝 + 𝑞 ) ) ) ) |
71 |
70
|
rexbidv |
⊢ ( 𝑁 = ( 𝑝 + 𝑞 ) → ( ∃ 𝑓 ∈ ( ℙ ↑m { 1 , 2 } ) ( 2 ≤ 3 ∧ 𝑁 = Σ 𝑘 ∈ { 1 , 2 } ( 𝑓 ‘ 𝑘 ) ) ↔ ∃ 𝑓 ∈ ( ℙ ↑m { 1 , 2 } ) ( 2 ≤ 3 ∧ Σ 𝑘 ∈ { 1 , 2 } ( 𝑓 ‘ 𝑘 ) = ( 𝑝 + 𝑞 ) ) ) ) |
72 |
71
|
3ad2ant3 |
⊢ ( ( 𝑝 ∈ Odd ∧ 𝑞 ∈ Odd ∧ 𝑁 = ( 𝑝 + 𝑞 ) ) → ( ∃ 𝑓 ∈ ( ℙ ↑m { 1 , 2 } ) ( 2 ≤ 3 ∧ 𝑁 = Σ 𝑘 ∈ { 1 , 2 } ( 𝑓 ‘ 𝑘 ) ) ↔ ∃ 𝑓 ∈ ( ℙ ↑m { 1 , 2 } ) ( 2 ≤ 3 ∧ Σ 𝑘 ∈ { 1 , 2 } ( 𝑓 ‘ 𝑘 ) = ( 𝑝 + 𝑞 ) ) ) ) |
73 |
72
|
adantl |
⊢ ( ( ( 𝑝 ∈ ℙ ∧ 𝑞 ∈ ℙ ) ∧ ( 𝑝 ∈ Odd ∧ 𝑞 ∈ Odd ∧ 𝑁 = ( 𝑝 + 𝑞 ) ) ) → ( ∃ 𝑓 ∈ ( ℙ ↑m { 1 , 2 } ) ( 2 ≤ 3 ∧ 𝑁 = Σ 𝑘 ∈ { 1 , 2 } ( 𝑓 ‘ 𝑘 ) ) ↔ ∃ 𝑓 ∈ ( ℙ ↑m { 1 , 2 } ) ( 2 ≤ 3 ∧ Σ 𝑘 ∈ { 1 , 2 } ( 𝑓 ‘ 𝑘 ) = ( 𝑝 + 𝑞 ) ) ) ) |
74 |
66 73
|
mpbird |
⊢ ( ( ( 𝑝 ∈ ℙ ∧ 𝑞 ∈ ℙ ) ∧ ( 𝑝 ∈ Odd ∧ 𝑞 ∈ Odd ∧ 𝑁 = ( 𝑝 + 𝑞 ) ) ) → ∃ 𝑓 ∈ ( ℙ ↑m { 1 , 2 } ) ( 2 ≤ 3 ∧ 𝑁 = Σ 𝑘 ∈ { 1 , 2 } ( 𝑓 ‘ 𝑘 ) ) ) |
75 |
3 20 74
|
rspcedvd |
⊢ ( ( ( 𝑝 ∈ ℙ ∧ 𝑞 ∈ ℙ ) ∧ ( 𝑝 ∈ Odd ∧ 𝑞 ∈ Odd ∧ 𝑁 = ( 𝑝 + 𝑞 ) ) ) → ∃ 𝑑 ∈ ℕ ∃ 𝑓 ∈ ( ℙ ↑m ( 1 ... 𝑑 ) ) ( 𝑑 ≤ 3 ∧ 𝑁 = Σ 𝑘 ∈ ( 1 ... 𝑑 ) ( 𝑓 ‘ 𝑘 ) ) ) |
76 |
75
|
a1d |
⊢ ( ( ( 𝑝 ∈ ℙ ∧ 𝑞 ∈ ℙ ) ∧ ( 𝑝 ∈ Odd ∧ 𝑞 ∈ Odd ∧ 𝑁 = ( 𝑝 + 𝑞 ) ) ) → ( 𝑁 ∈ Even → ∃ 𝑑 ∈ ℕ ∃ 𝑓 ∈ ( ℙ ↑m ( 1 ... 𝑑 ) ) ( 𝑑 ≤ 3 ∧ 𝑁 = Σ 𝑘 ∈ ( 1 ... 𝑑 ) ( 𝑓 ‘ 𝑘 ) ) ) ) |
77 |
76
|
ex |
⊢ ( ( 𝑝 ∈ ℙ ∧ 𝑞 ∈ ℙ ) → ( ( 𝑝 ∈ Odd ∧ 𝑞 ∈ Odd ∧ 𝑁 = ( 𝑝 + 𝑞 ) ) → ( 𝑁 ∈ Even → ∃ 𝑑 ∈ ℕ ∃ 𝑓 ∈ ( ℙ ↑m ( 1 ... 𝑑 ) ) ( 𝑑 ≤ 3 ∧ 𝑁 = Σ 𝑘 ∈ ( 1 ... 𝑑 ) ( 𝑓 ‘ 𝑘 ) ) ) ) ) |
78 |
77
|
rexlimivv |
⊢ ( ∃ 𝑝 ∈ ℙ ∃ 𝑞 ∈ ℙ ( 𝑝 ∈ Odd ∧ 𝑞 ∈ Odd ∧ 𝑁 = ( 𝑝 + 𝑞 ) ) → ( 𝑁 ∈ Even → ∃ 𝑑 ∈ ℕ ∃ 𝑓 ∈ ( ℙ ↑m ( 1 ... 𝑑 ) ) ( 𝑑 ≤ 3 ∧ 𝑁 = Σ 𝑘 ∈ ( 1 ... 𝑑 ) ( 𝑓 ‘ 𝑘 ) ) ) ) |
79 |
78
|
impcom |
⊢ ( ( 𝑁 ∈ Even ∧ ∃ 𝑝 ∈ ℙ ∃ 𝑞 ∈ ℙ ( 𝑝 ∈ Odd ∧ 𝑞 ∈ Odd ∧ 𝑁 = ( 𝑝 + 𝑞 ) ) ) → ∃ 𝑑 ∈ ℕ ∃ 𝑓 ∈ ( ℙ ↑m ( 1 ... 𝑑 ) ) ( 𝑑 ≤ 3 ∧ 𝑁 = Σ 𝑘 ∈ ( 1 ... 𝑑 ) ( 𝑓 ‘ 𝑘 ) ) ) |
80 |
1 79
|
sylbi |
⊢ ( 𝑁 ∈ GoldbachEven → ∃ 𝑑 ∈ ℕ ∃ 𝑓 ∈ ( ℙ ↑m ( 1 ... 𝑑 ) ) ( 𝑑 ≤ 3 ∧ 𝑁 = Σ 𝑘 ∈ ( 1 ... 𝑑 ) ( 𝑓 ‘ 𝑘 ) ) ) |