| Step | Hyp | Ref | Expression | 
						
							| 1 |  | elovmporab.o | ⊢ 𝑂  =  ( 𝑥  ∈  V ,  𝑦  ∈  V  ↦  { 𝑧  ∈  𝑀  ∣  𝜑 } ) | 
						
							| 2 |  | elovmporab.v | ⊢ ( ( 𝑋  ∈  V  ∧  𝑌  ∈  V )  →  𝑀  ∈  V ) | 
						
							| 3 | 1 | elmpocl | ⊢ ( 𝑍  ∈  ( 𝑋 𝑂 𝑌 )  →  ( 𝑋  ∈  V  ∧  𝑌  ∈  V ) ) | 
						
							| 4 | 1 | a1i | ⊢ ( ( 𝑋  ∈  V  ∧  𝑌  ∈  V )  →  𝑂  =  ( 𝑥  ∈  V ,  𝑦  ∈  V  ↦  { 𝑧  ∈  𝑀  ∣  𝜑 } ) ) | 
						
							| 5 |  | sbceq1a | ⊢ ( 𝑦  =  𝑌  →  ( 𝜑  ↔  [ 𝑌  /  𝑦 ] 𝜑 ) ) | 
						
							| 6 |  | sbceq1a | ⊢ ( 𝑥  =  𝑋  →  ( [ 𝑌  /  𝑦 ] 𝜑  ↔  [ 𝑋  /  𝑥 ] [ 𝑌  /  𝑦 ] 𝜑 ) ) | 
						
							| 7 | 5 6 | sylan9bbr | ⊢ ( ( 𝑥  =  𝑋  ∧  𝑦  =  𝑌 )  →  ( 𝜑  ↔  [ 𝑋  /  𝑥 ] [ 𝑌  /  𝑦 ] 𝜑 ) ) | 
						
							| 8 | 7 | adantl | ⊢ ( ( ( 𝑋  ∈  V  ∧  𝑌  ∈  V )  ∧  ( 𝑥  =  𝑋  ∧  𝑦  =  𝑌 ) )  →  ( 𝜑  ↔  [ 𝑋  /  𝑥 ] [ 𝑌  /  𝑦 ] 𝜑 ) ) | 
						
							| 9 | 8 | rabbidv | ⊢ ( ( ( 𝑋  ∈  V  ∧  𝑌  ∈  V )  ∧  ( 𝑥  =  𝑋  ∧  𝑦  =  𝑌 ) )  →  { 𝑧  ∈  𝑀  ∣  𝜑 }  =  { 𝑧  ∈  𝑀  ∣  [ 𝑋  /  𝑥 ] [ 𝑌  /  𝑦 ] 𝜑 } ) | 
						
							| 10 |  | eqidd | ⊢ ( ( ( 𝑋  ∈  V  ∧  𝑌  ∈  V )  ∧  𝑥  =  𝑋 )  →  V  =  V ) | 
						
							| 11 |  | simpl | ⊢ ( ( 𝑋  ∈  V  ∧  𝑌  ∈  V )  →  𝑋  ∈  V ) | 
						
							| 12 |  | simpr | ⊢ ( ( 𝑋  ∈  V  ∧  𝑌  ∈  V )  →  𝑌  ∈  V ) | 
						
							| 13 |  | rabexg | ⊢ ( 𝑀  ∈  V  →  { 𝑧  ∈  𝑀  ∣  [ 𝑋  /  𝑥 ] [ 𝑌  /  𝑦 ] 𝜑 }  ∈  V ) | 
						
							| 14 | 2 13 | syl | ⊢ ( ( 𝑋  ∈  V  ∧  𝑌  ∈  V )  →  { 𝑧  ∈  𝑀  ∣  [ 𝑋  /  𝑥 ] [ 𝑌  /  𝑦 ] 𝜑 }  ∈  V ) | 
						
							| 15 |  | nfcv | ⊢ Ⅎ 𝑥 𝑋 | 
						
							| 16 | 15 | nfel1 | ⊢ Ⅎ 𝑥 𝑋  ∈  V | 
						
							| 17 |  | nfcv | ⊢ Ⅎ 𝑥 𝑌 | 
						
							| 18 | 17 | nfel1 | ⊢ Ⅎ 𝑥 𝑌  ∈  V | 
						
							| 19 | 16 18 | nfan | ⊢ Ⅎ 𝑥 ( 𝑋  ∈  V  ∧  𝑌  ∈  V ) | 
						
							| 20 |  | nfcv | ⊢ Ⅎ 𝑦 𝑋 | 
						
							| 21 | 20 | nfel1 | ⊢ Ⅎ 𝑦 𝑋  ∈  V | 
						
							| 22 |  | nfcv | ⊢ Ⅎ 𝑦 𝑌 | 
						
							| 23 | 22 | nfel1 | ⊢ Ⅎ 𝑦 𝑌  ∈  V | 
						
							| 24 | 21 23 | nfan | ⊢ Ⅎ 𝑦 ( 𝑋  ∈  V  ∧  𝑌  ∈  V ) | 
						
							| 25 |  | nfsbc1v | ⊢ Ⅎ 𝑥 [ 𝑋  /  𝑥 ] [ 𝑌  /  𝑦 ] 𝜑 | 
						
							| 26 |  | nfcv | ⊢ Ⅎ 𝑥 𝑀 | 
						
							| 27 | 25 26 | nfrabw | ⊢ Ⅎ 𝑥 { 𝑧  ∈  𝑀  ∣  [ 𝑋  /  𝑥 ] [ 𝑌  /  𝑦 ] 𝜑 } | 
						
							| 28 |  | nfsbc1v | ⊢ Ⅎ 𝑦 [ 𝑌  /  𝑦 ] 𝜑 | 
						
							| 29 | 20 28 | nfsbcw | ⊢ Ⅎ 𝑦 [ 𝑋  /  𝑥 ] [ 𝑌  /  𝑦 ] 𝜑 | 
						
							| 30 |  | nfcv | ⊢ Ⅎ 𝑦 𝑀 | 
						
							| 31 | 29 30 | nfrabw | ⊢ Ⅎ 𝑦 { 𝑧  ∈  𝑀  ∣  [ 𝑋  /  𝑥 ] [ 𝑌  /  𝑦 ] 𝜑 } | 
						
							| 32 | 4 9 10 11 12 14 19 24 20 17 27 31 | ovmpodxf | ⊢ ( ( 𝑋  ∈  V  ∧  𝑌  ∈  V )  →  ( 𝑋 𝑂 𝑌 )  =  { 𝑧  ∈  𝑀  ∣  [ 𝑋  /  𝑥 ] [ 𝑌  /  𝑦 ] 𝜑 } ) | 
						
							| 33 | 32 | eleq2d | ⊢ ( ( 𝑋  ∈  V  ∧  𝑌  ∈  V )  →  ( 𝑍  ∈  ( 𝑋 𝑂 𝑌 )  ↔  𝑍  ∈  { 𝑧  ∈  𝑀  ∣  [ 𝑋  /  𝑥 ] [ 𝑌  /  𝑦 ] 𝜑 } ) ) | 
						
							| 34 |  | df-3an | ⊢ ( ( 𝑋  ∈  V  ∧  𝑌  ∈  V  ∧  𝑍  ∈  𝑀 )  ↔  ( ( 𝑋  ∈  V  ∧  𝑌  ∈  V )  ∧  𝑍  ∈  𝑀 ) ) | 
						
							| 35 | 34 | simplbi2com | ⊢ ( 𝑍  ∈  𝑀  →  ( ( 𝑋  ∈  V  ∧  𝑌  ∈  V )  →  ( 𝑋  ∈  V  ∧  𝑌  ∈  V  ∧  𝑍  ∈  𝑀 ) ) ) | 
						
							| 36 |  | elrabi | ⊢ ( 𝑍  ∈  { 𝑧  ∈  𝑀  ∣  [ 𝑋  /  𝑥 ] [ 𝑌  /  𝑦 ] 𝜑 }  →  𝑍  ∈  𝑀 ) | 
						
							| 37 | 35 36 | syl11 | ⊢ ( ( 𝑋  ∈  V  ∧  𝑌  ∈  V )  →  ( 𝑍  ∈  { 𝑧  ∈  𝑀  ∣  [ 𝑋  /  𝑥 ] [ 𝑌  /  𝑦 ] 𝜑 }  →  ( 𝑋  ∈  V  ∧  𝑌  ∈  V  ∧  𝑍  ∈  𝑀 ) ) ) | 
						
							| 38 | 33 37 | sylbid | ⊢ ( ( 𝑋  ∈  V  ∧  𝑌  ∈  V )  →  ( 𝑍  ∈  ( 𝑋 𝑂 𝑌 )  →  ( 𝑋  ∈  V  ∧  𝑌  ∈  V  ∧  𝑍  ∈  𝑀 ) ) ) | 
						
							| 39 | 3 38 | mpcom | ⊢ ( 𝑍  ∈  ( 𝑋 𝑂 𝑌 )  →  ( 𝑋  ∈  V  ∧  𝑌  ∈  V  ∧  𝑍  ∈  𝑀 ) ) |