| Step | Hyp | Ref | Expression | 
						
							| 1 |  | df-inr | ⊢ inr  =  ( 𝑥  ∈  V  ↦  〈 1o ,  𝑥 〉 ) | 
						
							| 2 |  | 1onn | ⊢ 1o  ∈  ω | 
						
							| 3 |  | snidg | ⊢ ( 1o  ∈  ω  →  1o  ∈  { 1o } ) | 
						
							| 4 | 2 3 | ax-mp | ⊢ 1o  ∈  { 1o } | 
						
							| 5 |  | opelxpi | ⊢ ( ( 1o  ∈  { 1o }  ∧  𝑥  ∈  V )  →  〈 1o ,  𝑥 〉  ∈  ( { 1o }  ×  V ) ) | 
						
							| 6 | 4 5 | mpan | ⊢ ( 𝑥  ∈  V  →  〈 1o ,  𝑥 〉  ∈  ( { 1o }  ×  V ) ) | 
						
							| 7 | 6 | adantl | ⊢ ( ( ⊤  ∧  𝑥  ∈  V )  →  〈 1o ,  𝑥 〉  ∈  ( { 1o }  ×  V ) ) | 
						
							| 8 |  | fvexd | ⊢ ( ( ⊤  ∧  𝑦  ∈  ( { 1o }  ×  V ) )  →  ( 2nd  ‘ 𝑦 )  ∈  V ) | 
						
							| 9 |  | 1st2nd2 | ⊢ ( 𝑦  ∈  ( { 1o }  ×  V )  →  𝑦  =  〈 ( 1st  ‘ 𝑦 ) ,  ( 2nd  ‘ 𝑦 ) 〉 ) | 
						
							| 10 |  | xp1st | ⊢ ( 𝑦  ∈  ( { 1o }  ×  V )  →  ( 1st  ‘ 𝑦 )  ∈  { 1o } ) | 
						
							| 11 |  | elsni | ⊢ ( ( 1st  ‘ 𝑦 )  ∈  { 1o }  →  ( 1st  ‘ 𝑦 )  =  1o ) | 
						
							| 12 | 10 11 | syl | ⊢ ( 𝑦  ∈  ( { 1o }  ×  V )  →  ( 1st  ‘ 𝑦 )  =  1o ) | 
						
							| 13 | 12 | opeq1d | ⊢ ( 𝑦  ∈  ( { 1o }  ×  V )  →  〈 ( 1st  ‘ 𝑦 ) ,  ( 2nd  ‘ 𝑦 ) 〉  =  〈 1o ,  ( 2nd  ‘ 𝑦 ) 〉 ) | 
						
							| 14 | 9 13 | eqtrd | ⊢ ( 𝑦  ∈  ( { 1o }  ×  V )  →  𝑦  =  〈 1o ,  ( 2nd  ‘ 𝑦 ) 〉 ) | 
						
							| 15 | 14 | eqeq2d | ⊢ ( 𝑦  ∈  ( { 1o }  ×  V )  →  ( 〈 1o ,  𝑥 〉  =  𝑦  ↔  〈 1o ,  𝑥 〉  =  〈 1o ,  ( 2nd  ‘ 𝑦 ) 〉 ) ) | 
						
							| 16 |  | eqcom | ⊢ ( 〈 1o ,  𝑥 〉  =  𝑦  ↔  𝑦  =  〈 1o ,  𝑥 〉 ) | 
						
							| 17 |  | eqid | ⊢ 1o  =  1o | 
						
							| 18 |  | 1oex | ⊢ 1o  ∈  V | 
						
							| 19 |  | vex | ⊢ 𝑥  ∈  V | 
						
							| 20 | 18 19 | opth | ⊢ ( 〈 1o ,  𝑥 〉  =  〈 1o ,  ( 2nd  ‘ 𝑦 ) 〉  ↔  ( 1o  =  1o  ∧  𝑥  =  ( 2nd  ‘ 𝑦 ) ) ) | 
						
							| 21 | 17 20 | mpbiran | ⊢ ( 〈 1o ,  𝑥 〉  =  〈 1o ,  ( 2nd  ‘ 𝑦 ) 〉  ↔  𝑥  =  ( 2nd  ‘ 𝑦 ) ) | 
						
							| 22 | 15 16 21 | 3bitr3g | ⊢ ( 𝑦  ∈  ( { 1o }  ×  V )  →  ( 𝑦  =  〈 1o ,  𝑥 〉  ↔  𝑥  =  ( 2nd  ‘ 𝑦 ) ) ) | 
						
							| 23 | 22 | bicomd | ⊢ ( 𝑦  ∈  ( { 1o }  ×  V )  →  ( 𝑥  =  ( 2nd  ‘ 𝑦 )  ↔  𝑦  =  〈 1o ,  𝑥 〉 ) ) | 
						
							| 24 | 23 | ad2antll | ⊢ ( ( ⊤  ∧  ( 𝑥  ∈  V  ∧  𝑦  ∈  ( { 1o }  ×  V ) ) )  →  ( 𝑥  =  ( 2nd  ‘ 𝑦 )  ↔  𝑦  =  〈 1o ,  𝑥 〉 ) ) | 
						
							| 25 | 1 7 8 24 | f1o2d | ⊢ ( ⊤  →  inr : V –1-1-onto→ ( { 1o }  ×  V ) ) | 
						
							| 26 | 25 | mptru | ⊢ inr : V –1-1-onto→ ( { 1o }  ×  V ) |