Step |
Hyp |
Ref |
Expression |
1 |
|
c0ex |
⊢ 0 ∈ V |
2 |
1
|
a1i |
⊢ ( 𝑁 ∈ ( ℕ0 ∖ { 0 } ) → 0 ∈ V ) |
3 |
|
1ex |
⊢ 1 ∈ V |
4 |
3
|
a1i |
⊢ ( 𝑁 ∈ ( ℕ0 ∖ { 0 } ) → 1 ∈ V ) |
5 |
|
df-fac |
⊢ ! = ( { 〈 0 , 1 〉 } ∪ seq 1 ( · , I ) ) |
6 |
|
nnuz |
⊢ ℕ = ( ℤ≥ ‘ 1 ) |
7 |
|
dfn2 |
⊢ ℕ = ( ℕ0 ∖ { 0 } ) |
8 |
6 7
|
eqtr3i |
⊢ ( ℤ≥ ‘ 1 ) = ( ℕ0 ∖ { 0 } ) |
9 |
8
|
reseq2i |
⊢ ( seq 1 ( · , I ) ↾ ( ℤ≥ ‘ 1 ) ) = ( seq 1 ( · , I ) ↾ ( ℕ0 ∖ { 0 } ) ) |
10 |
|
1z |
⊢ 1 ∈ ℤ |
11 |
|
seqfn |
⊢ ( 1 ∈ ℤ → seq 1 ( · , I ) Fn ( ℤ≥ ‘ 1 ) ) |
12 |
|
fnresdm |
⊢ ( seq 1 ( · , I ) Fn ( ℤ≥ ‘ 1 ) → ( seq 1 ( · , I ) ↾ ( ℤ≥ ‘ 1 ) ) = seq 1 ( · , I ) ) |
13 |
10 11 12
|
mp2b |
⊢ ( seq 1 ( · , I ) ↾ ( ℤ≥ ‘ 1 ) ) = seq 1 ( · , I ) |
14 |
9 13
|
eqtr3i |
⊢ ( seq 1 ( · , I ) ↾ ( ℕ0 ∖ { 0 } ) ) = seq 1 ( · , I ) |
15 |
14
|
uneq2i |
⊢ ( { 〈 0 , 1 〉 } ∪ ( seq 1 ( · , I ) ↾ ( ℕ0 ∖ { 0 } ) ) ) = ( { 〈 0 , 1 〉 } ∪ seq 1 ( · , I ) ) |
16 |
5 15
|
eqtr4i |
⊢ ! = ( { 〈 0 , 1 〉 } ∪ ( seq 1 ( · , I ) ↾ ( ℕ0 ∖ { 0 } ) ) ) |
17 |
|
id |
⊢ ( 𝑁 ∈ ( ℕ0 ∖ { 0 } ) → 𝑁 ∈ ( ℕ0 ∖ { 0 } ) ) |
18 |
2 4 16 17
|
fvsnun2 |
⊢ ( 𝑁 ∈ ( ℕ0 ∖ { 0 } ) → ( ! ‘ 𝑁 ) = ( seq 1 ( · , I ) ‘ 𝑁 ) ) |
19 |
18 7
|
eleq2s |
⊢ ( 𝑁 ∈ ℕ → ( ! ‘ 𝑁 ) = ( seq 1 ( · , I ) ‘ 𝑁 ) ) |