| Step | Hyp | Ref | Expression | 
						
							| 1 |  | prex | ⊢ { 1 ,  2 }  ∈  V | 
						
							| 2 |  | eqid | ⊢ ( pmTrsp ‘ { 1 ,  2 } )  =  ( pmTrsp ‘ { 1 ,  2 } ) | 
						
							| 3 | 2 | pmtrfval | ⊢ ( { 1 ,  2 }  ∈  V  →  ( pmTrsp ‘ { 1 ,  2 } )  =  ( 𝑝  ∈  { 𝑡  ∈  𝒫  { 1 ,  2 }  ∣  𝑡  ≈  2o }  ↦  ( 𝑧  ∈  { 1 ,  2 }  ↦  if ( 𝑧  ∈  𝑝 ,  ∪  ( 𝑝  ∖  { 𝑧 } ) ,  𝑧 ) ) ) ) | 
						
							| 4 | 1 3 | ax-mp | ⊢ ( pmTrsp ‘ { 1 ,  2 } )  =  ( 𝑝  ∈  { 𝑡  ∈  𝒫  { 1 ,  2 }  ∣  𝑡  ≈  2o }  ↦  ( 𝑧  ∈  { 1 ,  2 }  ↦  if ( 𝑧  ∈  𝑝 ,  ∪  ( 𝑝  ∖  { 𝑧 } ) ,  𝑧 ) ) ) | 
						
							| 5 |  | 1ex | ⊢ 1  ∈  V | 
						
							| 6 |  | 2nn0 | ⊢ 2  ∈  ℕ0 | 
						
							| 7 |  | 1ne2 | ⊢ 1  ≠  2 | 
						
							| 8 |  | pr2pwpr | ⊢ ( ( 1  ∈  V  ∧  2  ∈  ℕ0  ∧  1  ≠  2 )  →  { 𝑡  ∈  𝒫  { 1 ,  2 }  ∣  𝑡  ≈  2o }  =  { { 1 ,  2 } } ) | 
						
							| 9 | 5 6 7 8 | mp3an | ⊢ { 𝑡  ∈  𝒫  { 1 ,  2 }  ∣  𝑡  ≈  2o }  =  { { 1 ,  2 } } | 
						
							| 10 | 9 | mpteq1i | ⊢ ( 𝑝  ∈  { 𝑡  ∈  𝒫  { 1 ,  2 }  ∣  𝑡  ≈  2o }  ↦  ( 𝑧  ∈  { 1 ,  2 }  ↦  if ( 𝑧  ∈  𝑝 ,  ∪  ( 𝑝  ∖  { 𝑧 } ) ,  𝑧 ) ) )  =  ( 𝑝  ∈  { { 1 ,  2 } }  ↦  ( 𝑧  ∈  { 1 ,  2 }  ↦  if ( 𝑧  ∈  𝑝 ,  ∪  ( 𝑝  ∖  { 𝑧 } ) ,  𝑧 ) ) ) | 
						
							| 11 |  | elsni | ⊢ ( 𝑝  ∈  { { 1 ,  2 } }  →  𝑝  =  { 1 ,  2 } ) | 
						
							| 12 |  | eleq2 | ⊢ ( 𝑝  =  { 1 ,  2 }  →  ( 𝑧  ∈  𝑝  ↔  𝑧  ∈  { 1 ,  2 } ) ) | 
						
							| 13 | 12 | biimpar | ⊢ ( ( 𝑝  =  { 1 ,  2 }  ∧  𝑧  ∈  { 1 ,  2 } )  →  𝑧  ∈  𝑝 ) | 
						
							| 14 | 13 | iftrued | ⊢ ( ( 𝑝  =  { 1 ,  2 }  ∧  𝑧  ∈  { 1 ,  2 } )  →  if ( 𝑧  ∈  𝑝 ,  ∪  ( 𝑝  ∖  { 𝑧 } ) ,  𝑧 )  =  ∪  ( 𝑝  ∖  { 𝑧 } ) ) | 
						
							| 15 |  | elpri | ⊢ ( 𝑧  ∈  { 1 ,  2 }  →  ( 𝑧  =  1  ∨  𝑧  =  2 ) ) | 
						
							| 16 |  | 2ex | ⊢ 2  ∈  V | 
						
							| 17 | 16 | unisn | ⊢ ∪  { 2 }  =  2 | 
						
							| 18 |  | simpr | ⊢ ( ( 𝑧  =  1  ∧  𝑝  =  { 1 ,  2 } )  →  𝑝  =  { 1 ,  2 } ) | 
						
							| 19 |  | sneq | ⊢ ( 𝑧  =  1  →  { 𝑧 }  =  { 1 } ) | 
						
							| 20 | 19 | adantr | ⊢ ( ( 𝑧  =  1  ∧  𝑝  =  { 1 ,  2 } )  →  { 𝑧 }  =  { 1 } ) | 
						
							| 21 | 18 20 | difeq12d | ⊢ ( ( 𝑧  =  1  ∧  𝑝  =  { 1 ,  2 } )  →  ( 𝑝  ∖  { 𝑧 } )  =  ( { 1 ,  2 }  ∖  { 1 } ) ) | 
						
							| 22 |  | difprsn1 | ⊢ ( 1  ≠  2  →  ( { 1 ,  2 }  ∖  { 1 } )  =  { 2 } ) | 
						
							| 23 | 7 22 | ax-mp | ⊢ ( { 1 ,  2 }  ∖  { 1 } )  =  { 2 } | 
						
							| 24 | 21 23 | eqtrdi | ⊢ ( ( 𝑧  =  1  ∧  𝑝  =  { 1 ,  2 } )  →  ( 𝑝  ∖  { 𝑧 } )  =  { 2 } ) | 
						
							| 25 | 24 | unieqd | ⊢ ( ( 𝑧  =  1  ∧  𝑝  =  { 1 ,  2 } )  →  ∪  ( 𝑝  ∖  { 𝑧 } )  =  ∪  { 2 } ) | 
						
							| 26 |  | iftrue | ⊢ ( 𝑧  =  1  →  if ( 𝑧  =  1 ,  2 ,  1 )  =  2 ) | 
						
							| 27 | 26 | adantr | ⊢ ( ( 𝑧  =  1  ∧  𝑝  =  { 1 ,  2 } )  →  if ( 𝑧  =  1 ,  2 ,  1 )  =  2 ) | 
						
							| 28 | 17 25 27 | 3eqtr4a | ⊢ ( ( 𝑧  =  1  ∧  𝑝  =  { 1 ,  2 } )  →  ∪  ( 𝑝  ∖  { 𝑧 } )  =  if ( 𝑧  =  1 ,  2 ,  1 ) ) | 
						
							| 29 | 28 | ex | ⊢ ( 𝑧  =  1  →  ( 𝑝  =  { 1 ,  2 }  →  ∪  ( 𝑝  ∖  { 𝑧 } )  =  if ( 𝑧  =  1 ,  2 ,  1 ) ) ) | 
						
							| 30 | 5 | unisn | ⊢ ∪  { 1 }  =  1 | 
						
							| 31 |  | simpr | ⊢ ( ( 𝑧  =  2  ∧  𝑝  =  { 1 ,  2 } )  →  𝑝  =  { 1 ,  2 } ) | 
						
							| 32 |  | sneq | ⊢ ( 𝑧  =  2  →  { 𝑧 }  =  { 2 } ) | 
						
							| 33 | 32 | adantr | ⊢ ( ( 𝑧  =  2  ∧  𝑝  =  { 1 ,  2 } )  →  { 𝑧 }  =  { 2 } ) | 
						
							| 34 | 31 33 | difeq12d | ⊢ ( ( 𝑧  =  2  ∧  𝑝  =  { 1 ,  2 } )  →  ( 𝑝  ∖  { 𝑧 } )  =  ( { 1 ,  2 }  ∖  { 2 } ) ) | 
						
							| 35 |  | difprsn2 | ⊢ ( 1  ≠  2  →  ( { 1 ,  2 }  ∖  { 2 } )  =  { 1 } ) | 
						
							| 36 | 7 35 | ax-mp | ⊢ ( { 1 ,  2 }  ∖  { 2 } )  =  { 1 } | 
						
							| 37 | 34 36 | eqtrdi | ⊢ ( ( 𝑧  =  2  ∧  𝑝  =  { 1 ,  2 } )  →  ( 𝑝  ∖  { 𝑧 } )  =  { 1 } ) | 
						
							| 38 | 37 | unieqd | ⊢ ( ( 𝑧  =  2  ∧  𝑝  =  { 1 ,  2 } )  →  ∪  ( 𝑝  ∖  { 𝑧 } )  =  ∪  { 1 } ) | 
						
							| 39 | 7 | nesymi | ⊢ ¬  2  =  1 | 
						
							| 40 |  | eqeq1 | ⊢ ( 𝑧  =  2  →  ( 𝑧  =  1  ↔  2  =  1 ) ) | 
						
							| 41 | 39 40 | mtbiri | ⊢ ( 𝑧  =  2  →  ¬  𝑧  =  1 ) | 
						
							| 42 | 41 | iffalsed | ⊢ ( 𝑧  =  2  →  if ( 𝑧  =  1 ,  2 ,  1 )  =  1 ) | 
						
							| 43 | 42 | adantr | ⊢ ( ( 𝑧  =  2  ∧  𝑝  =  { 1 ,  2 } )  →  if ( 𝑧  =  1 ,  2 ,  1 )  =  1 ) | 
						
							| 44 | 30 38 43 | 3eqtr4a | ⊢ ( ( 𝑧  =  2  ∧  𝑝  =  { 1 ,  2 } )  →  ∪  ( 𝑝  ∖  { 𝑧 } )  =  if ( 𝑧  =  1 ,  2 ,  1 ) ) | 
						
							| 45 | 44 | ex | ⊢ ( 𝑧  =  2  →  ( 𝑝  =  { 1 ,  2 }  →  ∪  ( 𝑝  ∖  { 𝑧 } )  =  if ( 𝑧  =  1 ,  2 ,  1 ) ) ) | 
						
							| 46 | 29 45 | jaoi | ⊢ ( ( 𝑧  =  1  ∨  𝑧  =  2 )  →  ( 𝑝  =  { 1 ,  2 }  →  ∪  ( 𝑝  ∖  { 𝑧 } )  =  if ( 𝑧  =  1 ,  2 ,  1 ) ) ) | 
						
							| 47 | 15 46 | syl | ⊢ ( 𝑧  ∈  { 1 ,  2 }  →  ( 𝑝  =  { 1 ,  2 }  →  ∪  ( 𝑝  ∖  { 𝑧 } )  =  if ( 𝑧  =  1 ,  2 ,  1 ) ) ) | 
						
							| 48 | 47 | impcom | ⊢ ( ( 𝑝  =  { 1 ,  2 }  ∧  𝑧  ∈  { 1 ,  2 } )  →  ∪  ( 𝑝  ∖  { 𝑧 } )  =  if ( 𝑧  =  1 ,  2 ,  1 ) ) | 
						
							| 49 | 14 48 | eqtrd | ⊢ ( ( 𝑝  =  { 1 ,  2 }  ∧  𝑧  ∈  { 1 ,  2 } )  →  if ( 𝑧  ∈  𝑝 ,  ∪  ( 𝑝  ∖  { 𝑧 } ) ,  𝑧 )  =  if ( 𝑧  =  1 ,  2 ,  1 ) ) | 
						
							| 50 | 11 49 | sylan | ⊢ ( ( 𝑝  ∈  { { 1 ,  2 } }  ∧  𝑧  ∈  { 1 ,  2 } )  →  if ( 𝑧  ∈  𝑝 ,  ∪  ( 𝑝  ∖  { 𝑧 } ) ,  𝑧 )  =  if ( 𝑧  =  1 ,  2 ,  1 ) ) | 
						
							| 51 | 50 | mpteq2dva | ⊢ ( 𝑝  ∈  { { 1 ,  2 } }  →  ( 𝑧  ∈  { 1 ,  2 }  ↦  if ( 𝑧  ∈  𝑝 ,  ∪  ( 𝑝  ∖  { 𝑧 } ) ,  𝑧 ) )  =  ( 𝑧  ∈  { 1 ,  2 }  ↦  if ( 𝑧  =  1 ,  2 ,  1 ) ) ) | 
						
							| 52 | 51 | mpteq2ia | ⊢ ( 𝑝  ∈  { { 1 ,  2 } }  ↦  ( 𝑧  ∈  { 1 ,  2 }  ↦  if ( 𝑧  ∈  𝑝 ,  ∪  ( 𝑝  ∖  { 𝑧 } ) ,  𝑧 ) ) )  =  ( 𝑝  ∈  { { 1 ,  2 } }  ↦  ( 𝑧  ∈  { 1 ,  2 }  ↦  if ( 𝑧  =  1 ,  2 ,  1 ) ) ) | 
						
							| 53 | 10 52 | eqtri | ⊢ ( 𝑝  ∈  { 𝑡  ∈  𝒫  { 1 ,  2 }  ∣  𝑡  ≈  2o }  ↦  ( 𝑧  ∈  { 1 ,  2 }  ↦  if ( 𝑧  ∈  𝑝 ,  ∪  ( 𝑝  ∖  { 𝑧 } ) ,  𝑧 ) ) )  =  ( 𝑝  ∈  { { 1 ,  2 } }  ↦  ( 𝑧  ∈  { 1 ,  2 }  ↦  if ( 𝑧  =  1 ,  2 ,  1 ) ) ) | 
						
							| 54 | 4 53 | eqtri | ⊢ ( pmTrsp ‘ { 1 ,  2 } )  =  ( 𝑝  ∈  { { 1 ,  2 } }  ↦  ( 𝑧  ∈  { 1 ,  2 }  ↦  if ( 𝑧  =  1 ,  2 ,  1 ) ) ) |