| Step | Hyp | Ref | Expression | 
						
							| 1 |  | mapfzcons.1 | ⊢ 𝑀  =  ( 𝑁  +  1 ) | 
						
							| 2 |  | simp2 | ⊢ ( ( 𝑁  ∈  ℕ0  ∧  𝐴  ∈  ( 𝐵  ↑m  ( 1 ... 𝑁 ) )  ∧  𝐶  ∈  𝐵 )  →  𝐴  ∈  ( 𝐵  ↑m  ( 1 ... 𝑁 ) ) ) | 
						
							| 3 |  | elmapex | ⊢ ( 𝐴  ∈  ( 𝐵  ↑m  ( 1 ... 𝑁 ) )  →  ( 𝐵  ∈  V  ∧  ( 1 ... 𝑁 )  ∈  V ) ) | 
						
							| 4 | 3 | simpld | ⊢ ( 𝐴  ∈  ( 𝐵  ↑m  ( 1 ... 𝑁 ) )  →  𝐵  ∈  V ) | 
						
							| 5 | 4 | 3ad2ant2 | ⊢ ( ( 𝑁  ∈  ℕ0  ∧  𝐴  ∈  ( 𝐵  ↑m  ( 1 ... 𝑁 ) )  ∧  𝐶  ∈  𝐵 )  →  𝐵  ∈  V ) | 
						
							| 6 |  | ovex | ⊢ ( 1 ... 𝑁 )  ∈  V | 
						
							| 7 |  | elmapg | ⊢ ( ( 𝐵  ∈  V  ∧  ( 1 ... 𝑁 )  ∈  V )  →  ( 𝐴  ∈  ( 𝐵  ↑m  ( 1 ... 𝑁 ) )  ↔  𝐴 : ( 1 ... 𝑁 ) ⟶ 𝐵 ) ) | 
						
							| 8 | 5 6 7 | sylancl | ⊢ ( ( 𝑁  ∈  ℕ0  ∧  𝐴  ∈  ( 𝐵  ↑m  ( 1 ... 𝑁 ) )  ∧  𝐶  ∈  𝐵 )  →  ( 𝐴  ∈  ( 𝐵  ↑m  ( 1 ... 𝑁 ) )  ↔  𝐴 : ( 1 ... 𝑁 ) ⟶ 𝐵 ) ) | 
						
							| 9 | 2 8 | mpbid | ⊢ ( ( 𝑁  ∈  ℕ0  ∧  𝐴  ∈  ( 𝐵  ↑m  ( 1 ... 𝑁 ) )  ∧  𝐶  ∈  𝐵 )  →  𝐴 : ( 1 ... 𝑁 ) ⟶ 𝐵 ) | 
						
							| 10 |  | ovex | ⊢ ( 𝑁  +  1 )  ∈  V | 
						
							| 11 |  | simp3 | ⊢ ( ( 𝑁  ∈  ℕ0  ∧  𝐴  ∈  ( 𝐵  ↑m  ( 1 ... 𝑁 ) )  ∧  𝐶  ∈  𝐵 )  →  𝐶  ∈  𝐵 ) | 
						
							| 12 |  | f1osng | ⊢ ( ( ( 𝑁  +  1 )  ∈  V  ∧  𝐶  ∈  𝐵 )  →  { 〈 ( 𝑁  +  1 ) ,  𝐶 〉 } : { ( 𝑁  +  1 ) } –1-1-onto→ { 𝐶 } ) | 
						
							| 13 | 10 11 12 | sylancr | ⊢ ( ( 𝑁  ∈  ℕ0  ∧  𝐴  ∈  ( 𝐵  ↑m  ( 1 ... 𝑁 ) )  ∧  𝐶  ∈  𝐵 )  →  { 〈 ( 𝑁  +  1 ) ,  𝐶 〉 } : { ( 𝑁  +  1 ) } –1-1-onto→ { 𝐶 } ) | 
						
							| 14 |  | f1of | ⊢ ( { 〈 ( 𝑁  +  1 ) ,  𝐶 〉 } : { ( 𝑁  +  1 ) } –1-1-onto→ { 𝐶 }  →  { 〈 ( 𝑁  +  1 ) ,  𝐶 〉 } : { ( 𝑁  +  1 ) } ⟶ { 𝐶 } ) | 
						
							| 15 | 13 14 | syl | ⊢ ( ( 𝑁  ∈  ℕ0  ∧  𝐴  ∈  ( 𝐵  ↑m  ( 1 ... 𝑁 ) )  ∧  𝐶  ∈  𝐵 )  →  { 〈 ( 𝑁  +  1 ) ,  𝐶 〉 } : { ( 𝑁  +  1 ) } ⟶ { 𝐶 } ) | 
						
							| 16 |  | snssi | ⊢ ( 𝐶  ∈  𝐵  →  { 𝐶 }  ⊆  𝐵 ) | 
						
							| 17 | 16 | 3ad2ant3 | ⊢ ( ( 𝑁  ∈  ℕ0  ∧  𝐴  ∈  ( 𝐵  ↑m  ( 1 ... 𝑁 ) )  ∧  𝐶  ∈  𝐵 )  →  { 𝐶 }  ⊆  𝐵 ) | 
						
							| 18 | 15 17 | fssd | ⊢ ( ( 𝑁  ∈  ℕ0  ∧  𝐴  ∈  ( 𝐵  ↑m  ( 1 ... 𝑁 ) )  ∧  𝐶  ∈  𝐵 )  →  { 〈 ( 𝑁  +  1 ) ,  𝐶 〉 } : { ( 𝑁  +  1 ) } ⟶ 𝐵 ) | 
						
							| 19 |  | fzp1disj | ⊢ ( ( 1 ... 𝑁 )  ∩  { ( 𝑁  +  1 ) } )  =  ∅ | 
						
							| 20 | 19 | a1i | ⊢ ( ( 𝑁  ∈  ℕ0  ∧  𝐴  ∈  ( 𝐵  ↑m  ( 1 ... 𝑁 ) )  ∧  𝐶  ∈  𝐵 )  →  ( ( 1 ... 𝑁 )  ∩  { ( 𝑁  +  1 ) } )  =  ∅ ) | 
						
							| 21 |  | fun | ⊢ ( ( ( 𝐴 : ( 1 ... 𝑁 ) ⟶ 𝐵  ∧  { 〈 ( 𝑁  +  1 ) ,  𝐶 〉 } : { ( 𝑁  +  1 ) } ⟶ 𝐵 )  ∧  ( ( 1 ... 𝑁 )  ∩  { ( 𝑁  +  1 ) } )  =  ∅ )  →  ( 𝐴  ∪  { 〈 ( 𝑁  +  1 ) ,  𝐶 〉 } ) : ( ( 1 ... 𝑁 )  ∪  { ( 𝑁  +  1 ) } ) ⟶ ( 𝐵  ∪  𝐵 ) ) | 
						
							| 22 | 9 18 20 21 | syl21anc | ⊢ ( ( 𝑁  ∈  ℕ0  ∧  𝐴  ∈  ( 𝐵  ↑m  ( 1 ... 𝑁 ) )  ∧  𝐶  ∈  𝐵 )  →  ( 𝐴  ∪  { 〈 ( 𝑁  +  1 ) ,  𝐶 〉 } ) : ( ( 1 ... 𝑁 )  ∪  { ( 𝑁  +  1 ) } ) ⟶ ( 𝐵  ∪  𝐵 ) ) | 
						
							| 23 |  | 1z | ⊢ 1  ∈  ℤ | 
						
							| 24 |  | simp1 | ⊢ ( ( 𝑁  ∈  ℕ0  ∧  𝐴  ∈  ( 𝐵  ↑m  ( 1 ... 𝑁 ) )  ∧  𝐶  ∈  𝐵 )  →  𝑁  ∈  ℕ0 ) | 
						
							| 25 |  | nn0uz | ⊢ ℕ0  =  ( ℤ≥ ‘ 0 ) | 
						
							| 26 |  | 1m1e0 | ⊢ ( 1  −  1 )  =  0 | 
						
							| 27 | 26 | fveq2i | ⊢ ( ℤ≥ ‘ ( 1  −  1 ) )  =  ( ℤ≥ ‘ 0 ) | 
						
							| 28 | 25 27 | eqtr4i | ⊢ ℕ0  =  ( ℤ≥ ‘ ( 1  −  1 ) ) | 
						
							| 29 | 24 28 | eleqtrdi | ⊢ ( ( 𝑁  ∈  ℕ0  ∧  𝐴  ∈  ( 𝐵  ↑m  ( 1 ... 𝑁 ) )  ∧  𝐶  ∈  𝐵 )  →  𝑁  ∈  ( ℤ≥ ‘ ( 1  −  1 ) ) ) | 
						
							| 30 |  | fzsuc2 | ⊢ ( ( 1  ∈  ℤ  ∧  𝑁  ∈  ( ℤ≥ ‘ ( 1  −  1 ) ) )  →  ( 1 ... ( 𝑁  +  1 ) )  =  ( ( 1 ... 𝑁 )  ∪  { ( 𝑁  +  1 ) } ) ) | 
						
							| 31 | 23 29 30 | sylancr | ⊢ ( ( 𝑁  ∈  ℕ0  ∧  𝐴  ∈  ( 𝐵  ↑m  ( 1 ... 𝑁 ) )  ∧  𝐶  ∈  𝐵 )  →  ( 1 ... ( 𝑁  +  1 ) )  =  ( ( 1 ... 𝑁 )  ∪  { ( 𝑁  +  1 ) } ) ) | 
						
							| 32 | 31 | eqcomd | ⊢ ( ( 𝑁  ∈  ℕ0  ∧  𝐴  ∈  ( 𝐵  ↑m  ( 1 ... 𝑁 ) )  ∧  𝐶  ∈  𝐵 )  →  ( ( 1 ... 𝑁 )  ∪  { ( 𝑁  +  1 ) } )  =  ( 1 ... ( 𝑁  +  1 ) ) ) | 
						
							| 33 |  | unidm | ⊢ ( 𝐵  ∪  𝐵 )  =  𝐵 | 
						
							| 34 | 33 | a1i | ⊢ ( ( 𝑁  ∈  ℕ0  ∧  𝐴  ∈  ( 𝐵  ↑m  ( 1 ... 𝑁 ) )  ∧  𝐶  ∈  𝐵 )  →  ( 𝐵  ∪  𝐵 )  =  𝐵 ) | 
						
							| 35 | 32 34 | feq23d | ⊢ ( ( 𝑁  ∈  ℕ0  ∧  𝐴  ∈  ( 𝐵  ↑m  ( 1 ... 𝑁 ) )  ∧  𝐶  ∈  𝐵 )  →  ( ( 𝐴  ∪  { 〈 ( 𝑁  +  1 ) ,  𝐶 〉 } ) : ( ( 1 ... 𝑁 )  ∪  { ( 𝑁  +  1 ) } ) ⟶ ( 𝐵  ∪  𝐵 )  ↔  ( 𝐴  ∪  { 〈 ( 𝑁  +  1 ) ,  𝐶 〉 } ) : ( 1 ... ( 𝑁  +  1 ) ) ⟶ 𝐵 ) ) | 
						
							| 36 | 22 35 | mpbid | ⊢ ( ( 𝑁  ∈  ℕ0  ∧  𝐴  ∈  ( 𝐵  ↑m  ( 1 ... 𝑁 ) )  ∧  𝐶  ∈  𝐵 )  →  ( 𝐴  ∪  { 〈 ( 𝑁  +  1 ) ,  𝐶 〉 } ) : ( 1 ... ( 𝑁  +  1 ) ) ⟶ 𝐵 ) | 
						
							| 37 |  | ovex | ⊢ ( 1 ... ( 𝑁  +  1 ) )  ∈  V | 
						
							| 38 |  | elmapg | ⊢ ( ( 𝐵  ∈  V  ∧  ( 1 ... ( 𝑁  +  1 ) )  ∈  V )  →  ( ( 𝐴  ∪  { 〈 ( 𝑁  +  1 ) ,  𝐶 〉 } )  ∈  ( 𝐵  ↑m  ( 1 ... ( 𝑁  +  1 ) ) )  ↔  ( 𝐴  ∪  { 〈 ( 𝑁  +  1 ) ,  𝐶 〉 } ) : ( 1 ... ( 𝑁  +  1 ) ) ⟶ 𝐵 ) ) | 
						
							| 39 | 5 37 38 | sylancl | ⊢ ( ( 𝑁  ∈  ℕ0  ∧  𝐴  ∈  ( 𝐵  ↑m  ( 1 ... 𝑁 ) )  ∧  𝐶  ∈  𝐵 )  →  ( ( 𝐴  ∪  { 〈 ( 𝑁  +  1 ) ,  𝐶 〉 } )  ∈  ( 𝐵  ↑m  ( 1 ... ( 𝑁  +  1 ) ) )  ↔  ( 𝐴  ∪  { 〈 ( 𝑁  +  1 ) ,  𝐶 〉 } ) : ( 1 ... ( 𝑁  +  1 ) ) ⟶ 𝐵 ) ) | 
						
							| 40 | 36 39 | mpbird | ⊢ ( ( 𝑁  ∈  ℕ0  ∧  𝐴  ∈  ( 𝐵  ↑m  ( 1 ... 𝑁 ) )  ∧  𝐶  ∈  𝐵 )  →  ( 𝐴  ∪  { 〈 ( 𝑁  +  1 ) ,  𝐶 〉 } )  ∈  ( 𝐵  ↑m  ( 1 ... ( 𝑁  +  1 ) ) ) ) | 
						
							| 41 | 1 | opeq1i | ⊢ 〈 𝑀 ,  𝐶 〉  =  〈 ( 𝑁  +  1 ) ,  𝐶 〉 | 
						
							| 42 | 41 | sneqi | ⊢ { 〈 𝑀 ,  𝐶 〉 }  =  { 〈 ( 𝑁  +  1 ) ,  𝐶 〉 } | 
						
							| 43 | 42 | uneq2i | ⊢ ( 𝐴  ∪  { 〈 𝑀 ,  𝐶 〉 } )  =  ( 𝐴  ∪  { 〈 ( 𝑁  +  1 ) ,  𝐶 〉 } ) | 
						
							| 44 | 1 | oveq2i | ⊢ ( 1 ... 𝑀 )  =  ( 1 ... ( 𝑁  +  1 ) ) | 
						
							| 45 | 44 | oveq2i | ⊢ ( 𝐵  ↑m  ( 1 ... 𝑀 ) )  =  ( 𝐵  ↑m  ( 1 ... ( 𝑁  +  1 ) ) ) | 
						
							| 46 | 40 43 45 | 3eltr4g | ⊢ ( ( 𝑁  ∈  ℕ0  ∧  𝐴  ∈  ( 𝐵  ↑m  ( 1 ... 𝑁 ) )  ∧  𝐶  ∈  𝐵 )  →  ( 𝐴  ∪  { 〈 𝑀 ,  𝐶 〉 } )  ∈  ( 𝐵  ↑m  ( 1 ... 𝑀 ) ) ) |