| Step | Hyp | Ref | Expression | 
						
							| 1 |  | difeq2 | ⊢ ( 𝑥  =  𝑦  →  ( 𝑋  ∖  𝑥 )  =  ( 𝑋  ∖  𝑦 ) ) | 
						
							| 2 | 1 | breq1d | ⊢ ( 𝑥  =  𝑦  →  ( ( 𝑋  ∖  𝑥 )  ≺  𝑋  ↔  ( 𝑋  ∖  𝑦 )  ≺  𝑋 ) ) | 
						
							| 3 | 2 | elrab | ⊢ ( 𝑦  ∈  { 𝑥  ∈  𝒫  𝑋  ∣  ( 𝑋  ∖  𝑥 )  ≺  𝑋 }  ↔  ( 𝑦  ∈  𝒫  𝑋  ∧  ( 𝑋  ∖  𝑦 )  ≺  𝑋 ) ) | 
						
							| 4 |  | velpw | ⊢ ( 𝑦  ∈  𝒫  𝑋  ↔  𝑦  ⊆  𝑋 ) | 
						
							| 5 | 4 | anbi1i | ⊢ ( ( 𝑦  ∈  𝒫  𝑋  ∧  ( 𝑋  ∖  𝑦 )  ≺  𝑋 )  ↔  ( 𝑦  ⊆  𝑋  ∧  ( 𝑋  ∖  𝑦 )  ≺  𝑋 ) ) | 
						
							| 6 | 3 5 | bitri | ⊢ ( 𝑦  ∈  { 𝑥  ∈  𝒫  𝑋  ∣  ( 𝑋  ∖  𝑥 )  ≺  𝑋 }  ↔  ( 𝑦  ⊆  𝑋  ∧  ( 𝑋  ∖  𝑦 )  ≺  𝑋 ) ) | 
						
							| 7 | 6 | a1i | ⊢ ( ( 𝑋  ∈  dom  card  ∧  ω  ≼  𝑋 )  →  ( 𝑦  ∈  { 𝑥  ∈  𝒫  𝑋  ∣  ( 𝑋  ∖  𝑥 )  ≺  𝑋 }  ↔  ( 𝑦  ⊆  𝑋  ∧  ( 𝑋  ∖  𝑦 )  ≺  𝑋 ) ) ) | 
						
							| 8 |  | simpl | ⊢ ( ( 𝑋  ∈  dom  card  ∧  ω  ≼  𝑋 )  →  𝑋  ∈  dom  card ) | 
						
							| 9 |  | difid | ⊢ ( 𝑋  ∖  𝑋 )  =  ∅ | 
						
							| 10 |  | infn0 | ⊢ ( ω  ≼  𝑋  →  𝑋  ≠  ∅ ) | 
						
							| 11 | 10 | adantl | ⊢ ( ( 𝑋  ∈  dom  card  ∧  ω  ≼  𝑋 )  →  𝑋  ≠  ∅ ) | 
						
							| 12 |  | 0sdomg | ⊢ ( 𝑋  ∈  dom  card  →  ( ∅  ≺  𝑋  ↔  𝑋  ≠  ∅ ) ) | 
						
							| 13 | 12 | adantr | ⊢ ( ( 𝑋  ∈  dom  card  ∧  ω  ≼  𝑋 )  →  ( ∅  ≺  𝑋  ↔  𝑋  ≠  ∅ ) ) | 
						
							| 14 | 11 13 | mpbird | ⊢ ( ( 𝑋  ∈  dom  card  ∧  ω  ≼  𝑋 )  →  ∅  ≺  𝑋 ) | 
						
							| 15 | 9 14 | eqbrtrid | ⊢ ( ( 𝑋  ∈  dom  card  ∧  ω  ≼  𝑋 )  →  ( 𝑋  ∖  𝑋 )  ≺  𝑋 ) | 
						
							| 16 |  | difeq2 | ⊢ ( 𝑦  =  𝑋  →  ( 𝑋  ∖  𝑦 )  =  ( 𝑋  ∖  𝑋 ) ) | 
						
							| 17 | 16 | breq1d | ⊢ ( 𝑦  =  𝑋  →  ( ( 𝑋  ∖  𝑦 )  ≺  𝑋  ↔  ( 𝑋  ∖  𝑋 )  ≺  𝑋 ) ) | 
						
							| 18 | 17 | sbcieg | ⊢ ( 𝑋  ∈  dom  card  →  ( [ 𝑋  /  𝑦 ] ( 𝑋  ∖  𝑦 )  ≺  𝑋  ↔  ( 𝑋  ∖  𝑋 )  ≺  𝑋 ) ) | 
						
							| 19 | 18 | adantr | ⊢ ( ( 𝑋  ∈  dom  card  ∧  ω  ≼  𝑋 )  →  ( [ 𝑋  /  𝑦 ] ( 𝑋  ∖  𝑦 )  ≺  𝑋  ↔  ( 𝑋  ∖  𝑋 )  ≺  𝑋 ) ) | 
						
							| 20 | 15 19 | mpbird | ⊢ ( ( 𝑋  ∈  dom  card  ∧  ω  ≼  𝑋 )  →  [ 𝑋  /  𝑦 ] ( 𝑋  ∖  𝑦 )  ≺  𝑋 ) | 
						
							| 21 |  | sdomirr | ⊢ ¬  𝑋  ≺  𝑋 | 
						
							| 22 |  | 0ex | ⊢ ∅  ∈  V | 
						
							| 23 |  | difeq2 | ⊢ ( 𝑦  =  ∅  →  ( 𝑋  ∖  𝑦 )  =  ( 𝑋  ∖  ∅ ) ) | 
						
							| 24 |  | dif0 | ⊢ ( 𝑋  ∖  ∅ )  =  𝑋 | 
						
							| 25 | 23 24 | eqtrdi | ⊢ ( 𝑦  =  ∅  →  ( 𝑋  ∖  𝑦 )  =  𝑋 ) | 
						
							| 26 | 25 | breq1d | ⊢ ( 𝑦  =  ∅  →  ( ( 𝑋  ∖  𝑦 )  ≺  𝑋  ↔  𝑋  ≺  𝑋 ) ) | 
						
							| 27 | 22 26 | sbcie | ⊢ ( [ ∅  /  𝑦 ] ( 𝑋  ∖  𝑦 )  ≺  𝑋  ↔  𝑋  ≺  𝑋 ) | 
						
							| 28 | 27 | a1i | ⊢ ( ( 𝑋  ∈  dom  card  ∧  ω  ≼  𝑋 )  →  ( [ ∅  /  𝑦 ] ( 𝑋  ∖  𝑦 )  ≺  𝑋  ↔  𝑋  ≺  𝑋 ) ) | 
						
							| 29 | 21 28 | mtbiri | ⊢ ( ( 𝑋  ∈  dom  card  ∧  ω  ≼  𝑋 )  →  ¬  [ ∅  /  𝑦 ] ( 𝑋  ∖  𝑦 )  ≺  𝑋 ) | 
						
							| 30 |  | simp1l | ⊢ ( ( ( 𝑋  ∈  dom  card  ∧  ω  ≼  𝑋 )  ∧  𝑧  ⊆  𝑋  ∧  𝑤  ⊆  𝑧 )  →  𝑋  ∈  dom  card ) | 
						
							| 31 | 30 | difexd | ⊢ ( ( ( 𝑋  ∈  dom  card  ∧  ω  ≼  𝑋 )  ∧  𝑧  ⊆  𝑋  ∧  𝑤  ⊆  𝑧 )  →  ( 𝑋  ∖  𝑤 )  ∈  V ) | 
						
							| 32 |  | sscon | ⊢ ( 𝑤  ⊆  𝑧  →  ( 𝑋  ∖  𝑧 )  ⊆  ( 𝑋  ∖  𝑤 ) ) | 
						
							| 33 | 32 | 3ad2ant3 | ⊢ ( ( ( 𝑋  ∈  dom  card  ∧  ω  ≼  𝑋 )  ∧  𝑧  ⊆  𝑋  ∧  𝑤  ⊆  𝑧 )  →  ( 𝑋  ∖  𝑧 )  ⊆  ( 𝑋  ∖  𝑤 ) ) | 
						
							| 34 |  | ssdomg | ⊢ ( ( 𝑋  ∖  𝑤 )  ∈  V  →  ( ( 𝑋  ∖  𝑧 )  ⊆  ( 𝑋  ∖  𝑤 )  →  ( 𝑋  ∖  𝑧 )  ≼  ( 𝑋  ∖  𝑤 ) ) ) | 
						
							| 35 | 31 33 34 | sylc | ⊢ ( ( ( 𝑋  ∈  dom  card  ∧  ω  ≼  𝑋 )  ∧  𝑧  ⊆  𝑋  ∧  𝑤  ⊆  𝑧 )  →  ( 𝑋  ∖  𝑧 )  ≼  ( 𝑋  ∖  𝑤 ) ) | 
						
							| 36 |  | domsdomtr | ⊢ ( ( ( 𝑋  ∖  𝑧 )  ≼  ( 𝑋  ∖  𝑤 )  ∧  ( 𝑋  ∖  𝑤 )  ≺  𝑋 )  →  ( 𝑋  ∖  𝑧 )  ≺  𝑋 ) | 
						
							| 37 | 36 | ex | ⊢ ( ( 𝑋  ∖  𝑧 )  ≼  ( 𝑋  ∖  𝑤 )  →  ( ( 𝑋  ∖  𝑤 )  ≺  𝑋  →  ( 𝑋  ∖  𝑧 )  ≺  𝑋 ) ) | 
						
							| 38 | 35 37 | syl | ⊢ ( ( ( 𝑋  ∈  dom  card  ∧  ω  ≼  𝑋 )  ∧  𝑧  ⊆  𝑋  ∧  𝑤  ⊆  𝑧 )  →  ( ( 𝑋  ∖  𝑤 )  ≺  𝑋  →  ( 𝑋  ∖  𝑧 )  ≺  𝑋 ) ) | 
						
							| 39 |  | vex | ⊢ 𝑤  ∈  V | 
						
							| 40 |  | difeq2 | ⊢ ( 𝑦  =  𝑤  →  ( 𝑋  ∖  𝑦 )  =  ( 𝑋  ∖  𝑤 ) ) | 
						
							| 41 | 40 | breq1d | ⊢ ( 𝑦  =  𝑤  →  ( ( 𝑋  ∖  𝑦 )  ≺  𝑋  ↔  ( 𝑋  ∖  𝑤 )  ≺  𝑋 ) ) | 
						
							| 42 | 39 41 | sbcie | ⊢ ( [ 𝑤  /  𝑦 ] ( 𝑋  ∖  𝑦 )  ≺  𝑋  ↔  ( 𝑋  ∖  𝑤 )  ≺  𝑋 ) | 
						
							| 43 |  | vex | ⊢ 𝑧  ∈  V | 
						
							| 44 |  | difeq2 | ⊢ ( 𝑦  =  𝑧  →  ( 𝑋  ∖  𝑦 )  =  ( 𝑋  ∖  𝑧 ) ) | 
						
							| 45 | 44 | breq1d | ⊢ ( 𝑦  =  𝑧  →  ( ( 𝑋  ∖  𝑦 )  ≺  𝑋  ↔  ( 𝑋  ∖  𝑧 )  ≺  𝑋 ) ) | 
						
							| 46 | 43 45 | sbcie | ⊢ ( [ 𝑧  /  𝑦 ] ( 𝑋  ∖  𝑦 )  ≺  𝑋  ↔  ( 𝑋  ∖  𝑧 )  ≺  𝑋 ) | 
						
							| 47 | 38 42 46 | 3imtr4g | ⊢ ( ( ( 𝑋  ∈  dom  card  ∧  ω  ≼  𝑋 )  ∧  𝑧  ⊆  𝑋  ∧  𝑤  ⊆  𝑧 )  →  ( [ 𝑤  /  𝑦 ] ( 𝑋  ∖  𝑦 )  ≺  𝑋  →  [ 𝑧  /  𝑦 ] ( 𝑋  ∖  𝑦 )  ≺  𝑋 ) ) | 
						
							| 48 |  | infunsdom | ⊢ ( ( ( 𝑋  ∈  dom  card  ∧  ω  ≼  𝑋 )  ∧  ( ( 𝑋  ∖  𝑧 )  ≺  𝑋  ∧  ( 𝑋  ∖  𝑤 )  ≺  𝑋 ) )  →  ( ( 𝑋  ∖  𝑧 )  ∪  ( 𝑋  ∖  𝑤 ) )  ≺  𝑋 ) | 
						
							| 49 | 48 | ex | ⊢ ( ( 𝑋  ∈  dom  card  ∧  ω  ≼  𝑋 )  →  ( ( ( 𝑋  ∖  𝑧 )  ≺  𝑋  ∧  ( 𝑋  ∖  𝑤 )  ≺  𝑋 )  →  ( ( 𝑋  ∖  𝑧 )  ∪  ( 𝑋  ∖  𝑤 ) )  ≺  𝑋 ) ) | 
						
							| 50 |  | difindi | ⊢ ( 𝑋  ∖  ( 𝑧  ∩  𝑤 ) )  =  ( ( 𝑋  ∖  𝑧 )  ∪  ( 𝑋  ∖  𝑤 ) ) | 
						
							| 51 | 50 | breq1i | ⊢ ( ( 𝑋  ∖  ( 𝑧  ∩  𝑤 ) )  ≺  𝑋  ↔  ( ( 𝑋  ∖  𝑧 )  ∪  ( 𝑋  ∖  𝑤 ) )  ≺  𝑋 ) | 
						
							| 52 | 49 51 | imbitrrdi | ⊢ ( ( 𝑋  ∈  dom  card  ∧  ω  ≼  𝑋 )  →  ( ( ( 𝑋  ∖  𝑧 )  ≺  𝑋  ∧  ( 𝑋  ∖  𝑤 )  ≺  𝑋 )  →  ( 𝑋  ∖  ( 𝑧  ∩  𝑤 ) )  ≺  𝑋 ) ) | 
						
							| 53 | 52 | 3ad2ant1 | ⊢ ( ( ( 𝑋  ∈  dom  card  ∧  ω  ≼  𝑋 )  ∧  𝑧  ⊆  𝑋  ∧  𝑤  ⊆  𝑋 )  →  ( ( ( 𝑋  ∖  𝑧 )  ≺  𝑋  ∧  ( 𝑋  ∖  𝑤 )  ≺  𝑋 )  →  ( 𝑋  ∖  ( 𝑧  ∩  𝑤 ) )  ≺  𝑋 ) ) | 
						
							| 54 | 46 42 | anbi12i | ⊢ ( ( [ 𝑧  /  𝑦 ] ( 𝑋  ∖  𝑦 )  ≺  𝑋  ∧  [ 𝑤  /  𝑦 ] ( 𝑋  ∖  𝑦 )  ≺  𝑋 )  ↔  ( ( 𝑋  ∖  𝑧 )  ≺  𝑋  ∧  ( 𝑋  ∖  𝑤 )  ≺  𝑋 ) ) | 
						
							| 55 | 43 | inex1 | ⊢ ( 𝑧  ∩  𝑤 )  ∈  V | 
						
							| 56 |  | difeq2 | ⊢ ( 𝑦  =  ( 𝑧  ∩  𝑤 )  →  ( 𝑋  ∖  𝑦 )  =  ( 𝑋  ∖  ( 𝑧  ∩  𝑤 ) ) ) | 
						
							| 57 | 56 | breq1d | ⊢ ( 𝑦  =  ( 𝑧  ∩  𝑤 )  →  ( ( 𝑋  ∖  𝑦 )  ≺  𝑋  ↔  ( 𝑋  ∖  ( 𝑧  ∩  𝑤 ) )  ≺  𝑋 ) ) | 
						
							| 58 | 55 57 | sbcie | ⊢ ( [ ( 𝑧  ∩  𝑤 )  /  𝑦 ] ( 𝑋  ∖  𝑦 )  ≺  𝑋  ↔  ( 𝑋  ∖  ( 𝑧  ∩  𝑤 ) )  ≺  𝑋 ) | 
						
							| 59 | 53 54 58 | 3imtr4g | ⊢ ( ( ( 𝑋  ∈  dom  card  ∧  ω  ≼  𝑋 )  ∧  𝑧  ⊆  𝑋  ∧  𝑤  ⊆  𝑋 )  →  ( ( [ 𝑧  /  𝑦 ] ( 𝑋  ∖  𝑦 )  ≺  𝑋  ∧  [ 𝑤  /  𝑦 ] ( 𝑋  ∖  𝑦 )  ≺  𝑋 )  →  [ ( 𝑧  ∩  𝑤 )  /  𝑦 ] ( 𝑋  ∖  𝑦 )  ≺  𝑋 ) ) | 
						
							| 60 | 7 8 20 29 47 59 | isfild | ⊢ ( ( 𝑋  ∈  dom  card  ∧  ω  ≼  𝑋 )  →  { 𝑥  ∈  𝒫  𝑋  ∣  ( 𝑋  ∖  𝑥 )  ≺  𝑋 }  ∈  ( Fil ‘ 𝑋 ) ) |