| Step | Hyp | Ref | Expression | 
						
							| 1 |  | axlowdimlem7.1 | ⊢ 𝑃  =  ( { 〈 3 ,  - 1 〉 }  ∪  ( ( ( 1 ... 𝑁 )  ∖  { 3 } )  ×  { 0 } ) ) | 
						
							| 2 |  | eqid | ⊢ { 〈 3 ,  - 1 〉 }  =  { 〈 3 ,  - 1 〉 } | 
						
							| 3 |  | 3ex | ⊢ 3  ∈  V | 
						
							| 4 |  | negex | ⊢ - 1  ∈  V | 
						
							| 5 | 3 4 | fsn | ⊢ ( { 〈 3 ,  - 1 〉 } : { 3 } ⟶ { - 1 }  ↔  { 〈 3 ,  - 1 〉 }  =  { 〈 3 ,  - 1 〉 } ) | 
						
							| 6 | 2 5 | mpbir | ⊢ { 〈 3 ,  - 1 〉 } : { 3 } ⟶ { - 1 } | 
						
							| 7 |  | neg1rr | ⊢ - 1  ∈  ℝ | 
						
							| 8 |  | snssi | ⊢ ( - 1  ∈  ℝ  →  { - 1 }  ⊆  ℝ ) | 
						
							| 9 | 7 8 | ax-mp | ⊢ { - 1 }  ⊆  ℝ | 
						
							| 10 |  | fss | ⊢ ( ( { 〈 3 ,  - 1 〉 } : { 3 } ⟶ { - 1 }  ∧  { - 1 }  ⊆  ℝ )  →  { 〈 3 ,  - 1 〉 } : { 3 } ⟶ ℝ ) | 
						
							| 11 | 6 9 10 | mp2an | ⊢ { 〈 3 ,  - 1 〉 } : { 3 } ⟶ ℝ | 
						
							| 12 |  | 0re | ⊢ 0  ∈  ℝ | 
						
							| 13 | 12 | fconst6 | ⊢ ( ( ( 1 ... 𝑁 )  ∖  { 3 } )  ×  { 0 } ) : ( ( 1 ... 𝑁 )  ∖  { 3 } ) ⟶ ℝ | 
						
							| 14 | 11 13 | pm3.2i | ⊢ ( { 〈 3 ,  - 1 〉 } : { 3 } ⟶ ℝ  ∧  ( ( ( 1 ... 𝑁 )  ∖  { 3 } )  ×  { 0 } ) : ( ( 1 ... 𝑁 )  ∖  { 3 } ) ⟶ ℝ ) | 
						
							| 15 |  | disjdif | ⊢ ( { 3 }  ∩  ( ( 1 ... 𝑁 )  ∖  { 3 } ) )  =  ∅ | 
						
							| 16 |  | fun2 | ⊢ ( ( ( { 〈 3 ,  - 1 〉 } : { 3 } ⟶ ℝ  ∧  ( ( ( 1 ... 𝑁 )  ∖  { 3 } )  ×  { 0 } ) : ( ( 1 ... 𝑁 )  ∖  { 3 } ) ⟶ ℝ )  ∧  ( { 3 }  ∩  ( ( 1 ... 𝑁 )  ∖  { 3 } ) )  =  ∅ )  →  ( { 〈 3 ,  - 1 〉 }  ∪  ( ( ( 1 ... 𝑁 )  ∖  { 3 } )  ×  { 0 } ) ) : ( { 3 }  ∪  ( ( 1 ... 𝑁 )  ∖  { 3 } ) ) ⟶ ℝ ) | 
						
							| 17 | 14 15 16 | mp2an | ⊢ ( { 〈 3 ,  - 1 〉 }  ∪  ( ( ( 1 ... 𝑁 )  ∖  { 3 } )  ×  { 0 } ) ) : ( { 3 }  ∪  ( ( 1 ... 𝑁 )  ∖  { 3 } ) ) ⟶ ℝ | 
						
							| 18 |  | eluzle | ⊢ ( 𝑁  ∈  ( ℤ≥ ‘ 3 )  →  3  ≤  𝑁 ) | 
						
							| 19 |  | 1le3 | ⊢ 1  ≤  3 | 
						
							| 20 | 18 19 | jctil | ⊢ ( 𝑁  ∈  ( ℤ≥ ‘ 3 )  →  ( 1  ≤  3  ∧  3  ≤  𝑁 ) ) | 
						
							| 21 |  | 3z | ⊢ 3  ∈  ℤ | 
						
							| 22 |  | 1z | ⊢ 1  ∈  ℤ | 
						
							| 23 |  | eluzelz | ⊢ ( 𝑁  ∈  ( ℤ≥ ‘ 3 )  →  𝑁  ∈  ℤ ) | 
						
							| 24 |  | elfz | ⊢ ( ( 3  ∈  ℤ  ∧  1  ∈  ℤ  ∧  𝑁  ∈  ℤ )  →  ( 3  ∈  ( 1 ... 𝑁 )  ↔  ( 1  ≤  3  ∧  3  ≤  𝑁 ) ) ) | 
						
							| 25 | 21 22 23 24 | mp3an12i | ⊢ ( 𝑁  ∈  ( ℤ≥ ‘ 3 )  →  ( 3  ∈  ( 1 ... 𝑁 )  ↔  ( 1  ≤  3  ∧  3  ≤  𝑁 ) ) ) | 
						
							| 26 | 20 25 | mpbird | ⊢ ( 𝑁  ∈  ( ℤ≥ ‘ 3 )  →  3  ∈  ( 1 ... 𝑁 ) ) | 
						
							| 27 | 26 | snssd | ⊢ ( 𝑁  ∈  ( ℤ≥ ‘ 3 )  →  { 3 }  ⊆  ( 1 ... 𝑁 ) ) | 
						
							| 28 |  | undif | ⊢ ( { 3 }  ⊆  ( 1 ... 𝑁 )  ↔  ( { 3 }  ∪  ( ( 1 ... 𝑁 )  ∖  { 3 } ) )  =  ( 1 ... 𝑁 ) ) | 
						
							| 29 | 27 28 | sylib | ⊢ ( 𝑁  ∈  ( ℤ≥ ‘ 3 )  →  ( { 3 }  ∪  ( ( 1 ... 𝑁 )  ∖  { 3 } ) )  =  ( 1 ... 𝑁 ) ) | 
						
							| 30 | 29 | feq2d | ⊢ ( 𝑁  ∈  ( ℤ≥ ‘ 3 )  →  ( ( { 〈 3 ,  - 1 〉 }  ∪  ( ( ( 1 ... 𝑁 )  ∖  { 3 } )  ×  { 0 } ) ) : ( { 3 }  ∪  ( ( 1 ... 𝑁 )  ∖  { 3 } ) ) ⟶ ℝ  ↔  ( { 〈 3 ,  - 1 〉 }  ∪  ( ( ( 1 ... 𝑁 )  ∖  { 3 } )  ×  { 0 } ) ) : ( 1 ... 𝑁 ) ⟶ ℝ ) ) | 
						
							| 31 | 17 30 | mpbii | ⊢ ( 𝑁  ∈  ( ℤ≥ ‘ 3 )  →  ( { 〈 3 ,  - 1 〉 }  ∪  ( ( ( 1 ... 𝑁 )  ∖  { 3 } )  ×  { 0 } ) ) : ( 1 ... 𝑁 ) ⟶ ℝ ) | 
						
							| 32 |  | eluzge3nn | ⊢ ( 𝑁  ∈  ( ℤ≥ ‘ 3 )  →  𝑁  ∈  ℕ ) | 
						
							| 33 |  | elee | ⊢ ( 𝑁  ∈  ℕ  →  ( ( { 〈 3 ,  - 1 〉 }  ∪  ( ( ( 1 ... 𝑁 )  ∖  { 3 } )  ×  { 0 } ) )  ∈  ( 𝔼 ‘ 𝑁 )  ↔  ( { 〈 3 ,  - 1 〉 }  ∪  ( ( ( 1 ... 𝑁 )  ∖  { 3 } )  ×  { 0 } ) ) : ( 1 ... 𝑁 ) ⟶ ℝ ) ) | 
						
							| 34 | 32 33 | syl | ⊢ ( 𝑁  ∈  ( ℤ≥ ‘ 3 )  →  ( ( { 〈 3 ,  - 1 〉 }  ∪  ( ( ( 1 ... 𝑁 )  ∖  { 3 } )  ×  { 0 } ) )  ∈  ( 𝔼 ‘ 𝑁 )  ↔  ( { 〈 3 ,  - 1 〉 }  ∪  ( ( ( 1 ... 𝑁 )  ∖  { 3 } )  ×  { 0 } ) ) : ( 1 ... 𝑁 ) ⟶ ℝ ) ) | 
						
							| 35 | 31 34 | mpbird | ⊢ ( 𝑁  ∈  ( ℤ≥ ‘ 3 )  →  ( { 〈 3 ,  - 1 〉 }  ∪  ( ( ( 1 ... 𝑁 )  ∖  { 3 } )  ×  { 0 } ) )  ∈  ( 𝔼 ‘ 𝑁 ) ) | 
						
							| 36 | 1 35 | eqeltrid | ⊢ ( 𝑁  ∈  ( ℤ≥ ‘ 3 )  →  𝑃  ∈  ( 𝔼 ‘ 𝑁 ) ) |