Step |
Hyp |
Ref |
Expression |
1 |
|
coe1fval.a |
⊢ 𝐴 = ( coe1 ‘ 𝐹 ) |
2 |
|
df1o2 |
⊢ 1o = { ∅ } |
3 |
|
nn0ex |
⊢ ℕ0 ∈ V |
4 |
|
0ex |
⊢ ∅ ∈ V |
5 |
2 3 4
|
mapsnconst |
⊢ ( 𝑋 ∈ ( ℕ0 ↑m 1o ) → 𝑋 = ( 1o × { ( 𝑋 ‘ ∅ ) } ) ) |
6 |
5
|
adantl |
⊢ ( ( 𝐹 ∈ 𝑉 ∧ 𝑋 ∈ ( ℕ0 ↑m 1o ) ) → 𝑋 = ( 1o × { ( 𝑋 ‘ ∅ ) } ) ) |
7 |
6
|
fveq2d |
⊢ ( ( 𝐹 ∈ 𝑉 ∧ 𝑋 ∈ ( ℕ0 ↑m 1o ) ) → ( 𝐹 ‘ 𝑋 ) = ( 𝐹 ‘ ( 1o × { ( 𝑋 ‘ ∅ ) } ) ) ) |
8 |
|
elmapi |
⊢ ( 𝑋 ∈ ( ℕ0 ↑m 1o ) → 𝑋 : 1o ⟶ ℕ0 ) |
9 |
|
0lt1o |
⊢ ∅ ∈ 1o |
10 |
|
ffvelrn |
⊢ ( ( 𝑋 : 1o ⟶ ℕ0 ∧ ∅ ∈ 1o ) → ( 𝑋 ‘ ∅ ) ∈ ℕ0 ) |
11 |
8 9 10
|
sylancl |
⊢ ( 𝑋 ∈ ( ℕ0 ↑m 1o ) → ( 𝑋 ‘ ∅ ) ∈ ℕ0 ) |
12 |
1
|
coe1fv |
⊢ ( ( 𝐹 ∈ 𝑉 ∧ ( 𝑋 ‘ ∅ ) ∈ ℕ0 ) → ( 𝐴 ‘ ( 𝑋 ‘ ∅ ) ) = ( 𝐹 ‘ ( 1o × { ( 𝑋 ‘ ∅ ) } ) ) ) |
13 |
11 12
|
sylan2 |
⊢ ( ( 𝐹 ∈ 𝑉 ∧ 𝑋 ∈ ( ℕ0 ↑m 1o ) ) → ( 𝐴 ‘ ( 𝑋 ‘ ∅ ) ) = ( 𝐹 ‘ ( 1o × { ( 𝑋 ‘ ∅ ) } ) ) ) |
14 |
7 13
|
eqtr4d |
⊢ ( ( 𝐹 ∈ 𝑉 ∧ 𝑋 ∈ ( ℕ0 ↑m 1o ) ) → ( 𝐹 ‘ 𝑋 ) = ( 𝐴 ‘ ( 𝑋 ‘ ∅ ) ) ) |