| Step | Hyp | Ref | Expression | 
						
							| 1 |  | sseq2 | ⊢ ( 𝐴  =  𝐵  →  ( 𝑥  ⊆  𝐴  ↔  𝑥  ⊆  𝐵 ) ) | 
						
							| 2 | 1 | 3ad2ant2 | ⊢ ( ( 𝑅  =  𝑆  ∧  𝐴  =  𝐵  ∧  𝐹  =  𝐺 )  →  ( 𝑥  ⊆  𝐴  ↔  𝑥  ⊆  𝐵 ) ) | 
						
							| 3 |  | predeq1 | ⊢ ( 𝑅  =  𝑆  →  Pred ( 𝑅 ,  𝐴 ,  𝑦 )  =  Pred ( 𝑆 ,  𝐴 ,  𝑦 ) ) | 
						
							| 4 |  | predeq2 | ⊢ ( 𝐴  =  𝐵  →  Pred ( 𝑆 ,  𝐴 ,  𝑦 )  =  Pred ( 𝑆 ,  𝐵 ,  𝑦 ) ) | 
						
							| 5 | 3 4 | sylan9eq | ⊢ ( ( 𝑅  =  𝑆  ∧  𝐴  =  𝐵 )  →  Pred ( 𝑅 ,  𝐴 ,  𝑦 )  =  Pred ( 𝑆 ,  𝐵 ,  𝑦 ) ) | 
						
							| 6 | 5 | 3adant3 | ⊢ ( ( 𝑅  =  𝑆  ∧  𝐴  =  𝐵  ∧  𝐹  =  𝐺 )  →  Pred ( 𝑅 ,  𝐴 ,  𝑦 )  =  Pred ( 𝑆 ,  𝐵 ,  𝑦 ) ) | 
						
							| 7 | 6 | sseq1d | ⊢ ( ( 𝑅  =  𝑆  ∧  𝐴  =  𝐵  ∧  𝐹  =  𝐺 )  →  ( Pred ( 𝑅 ,  𝐴 ,  𝑦 )  ⊆  𝑥  ↔  Pred ( 𝑆 ,  𝐵 ,  𝑦 )  ⊆  𝑥 ) ) | 
						
							| 8 | 7 | ralbidv | ⊢ ( ( 𝑅  =  𝑆  ∧  𝐴  =  𝐵  ∧  𝐹  =  𝐺 )  →  ( ∀ 𝑦  ∈  𝑥 Pred ( 𝑅 ,  𝐴 ,  𝑦 )  ⊆  𝑥  ↔  ∀ 𝑦  ∈  𝑥 Pred ( 𝑆 ,  𝐵 ,  𝑦 )  ⊆  𝑥 ) ) | 
						
							| 9 | 2 8 | anbi12d | ⊢ ( ( 𝑅  =  𝑆  ∧  𝐴  =  𝐵  ∧  𝐹  =  𝐺 )  →  ( ( 𝑥  ⊆  𝐴  ∧  ∀ 𝑦  ∈  𝑥 Pred ( 𝑅 ,  𝐴 ,  𝑦 )  ⊆  𝑥 )  ↔  ( 𝑥  ⊆  𝐵  ∧  ∀ 𝑦  ∈  𝑥 Pred ( 𝑆 ,  𝐵 ,  𝑦 )  ⊆  𝑥 ) ) ) | 
						
							| 10 |  | simp3 | ⊢ ( ( 𝑅  =  𝑆  ∧  𝐴  =  𝐵  ∧  𝐹  =  𝐺 )  →  𝐹  =  𝐺 ) | 
						
							| 11 | 5 | reseq2d | ⊢ ( ( 𝑅  =  𝑆  ∧  𝐴  =  𝐵 )  →  ( 𝑓  ↾  Pred ( 𝑅 ,  𝐴 ,  𝑦 ) )  =  ( 𝑓  ↾  Pred ( 𝑆 ,  𝐵 ,  𝑦 ) ) ) | 
						
							| 12 | 11 | 3adant3 | ⊢ ( ( 𝑅  =  𝑆  ∧  𝐴  =  𝐵  ∧  𝐹  =  𝐺 )  →  ( 𝑓  ↾  Pred ( 𝑅 ,  𝐴 ,  𝑦 ) )  =  ( 𝑓  ↾  Pred ( 𝑆 ,  𝐵 ,  𝑦 ) ) ) | 
						
							| 13 | 10 12 | fveq12d | ⊢ ( ( 𝑅  =  𝑆  ∧  𝐴  =  𝐵  ∧  𝐹  =  𝐺 )  →  ( 𝐹 ‘ ( 𝑓  ↾  Pred ( 𝑅 ,  𝐴 ,  𝑦 ) ) )  =  ( 𝐺 ‘ ( 𝑓  ↾  Pred ( 𝑆 ,  𝐵 ,  𝑦 ) ) ) ) | 
						
							| 14 | 13 | eqeq2d | ⊢ ( ( 𝑅  =  𝑆  ∧  𝐴  =  𝐵  ∧  𝐹  =  𝐺 )  →  ( ( 𝑓 ‘ 𝑦 )  =  ( 𝐹 ‘ ( 𝑓  ↾  Pred ( 𝑅 ,  𝐴 ,  𝑦 ) ) )  ↔  ( 𝑓 ‘ 𝑦 )  =  ( 𝐺 ‘ ( 𝑓  ↾  Pred ( 𝑆 ,  𝐵 ,  𝑦 ) ) ) ) ) | 
						
							| 15 | 14 | ralbidv | ⊢ ( ( 𝑅  =  𝑆  ∧  𝐴  =  𝐵  ∧  𝐹  =  𝐺 )  →  ( ∀ 𝑦  ∈  𝑥 ( 𝑓 ‘ 𝑦 )  =  ( 𝐹 ‘ ( 𝑓  ↾  Pred ( 𝑅 ,  𝐴 ,  𝑦 ) ) )  ↔  ∀ 𝑦  ∈  𝑥 ( 𝑓 ‘ 𝑦 )  =  ( 𝐺 ‘ ( 𝑓  ↾  Pred ( 𝑆 ,  𝐵 ,  𝑦 ) ) ) ) ) | 
						
							| 16 | 9 15 | 3anbi23d | ⊢ ( ( 𝑅  =  𝑆  ∧  𝐴  =  𝐵  ∧  𝐹  =  𝐺 )  →  ( ( 𝑓  Fn  𝑥  ∧  ( 𝑥  ⊆  𝐴  ∧  ∀ 𝑦  ∈  𝑥 Pred ( 𝑅 ,  𝐴 ,  𝑦 )  ⊆  𝑥 )  ∧  ∀ 𝑦  ∈  𝑥 ( 𝑓 ‘ 𝑦 )  =  ( 𝐹 ‘ ( 𝑓  ↾  Pred ( 𝑅 ,  𝐴 ,  𝑦 ) ) ) )  ↔  ( 𝑓  Fn  𝑥  ∧  ( 𝑥  ⊆  𝐵  ∧  ∀ 𝑦  ∈  𝑥 Pred ( 𝑆 ,  𝐵 ,  𝑦 )  ⊆  𝑥 )  ∧  ∀ 𝑦  ∈  𝑥 ( 𝑓 ‘ 𝑦 )  =  ( 𝐺 ‘ ( 𝑓  ↾  Pred ( 𝑆 ,  𝐵 ,  𝑦 ) ) ) ) ) ) | 
						
							| 17 | 16 | exbidv | ⊢ ( ( 𝑅  =  𝑆  ∧  𝐴  =  𝐵  ∧  𝐹  =  𝐺 )  →  ( ∃ 𝑥 ( 𝑓  Fn  𝑥  ∧  ( 𝑥  ⊆  𝐴  ∧  ∀ 𝑦  ∈  𝑥 Pred ( 𝑅 ,  𝐴 ,  𝑦 )  ⊆  𝑥 )  ∧  ∀ 𝑦  ∈  𝑥 ( 𝑓 ‘ 𝑦 )  =  ( 𝐹 ‘ ( 𝑓  ↾  Pred ( 𝑅 ,  𝐴 ,  𝑦 ) ) ) )  ↔  ∃ 𝑥 ( 𝑓  Fn  𝑥  ∧  ( 𝑥  ⊆  𝐵  ∧  ∀ 𝑦  ∈  𝑥 Pred ( 𝑆 ,  𝐵 ,  𝑦 )  ⊆  𝑥 )  ∧  ∀ 𝑦  ∈  𝑥 ( 𝑓 ‘ 𝑦 )  =  ( 𝐺 ‘ ( 𝑓  ↾  Pred ( 𝑆 ,  𝐵 ,  𝑦 ) ) ) ) ) ) | 
						
							| 18 | 17 | abbidv | ⊢ ( ( 𝑅  =  𝑆  ∧  𝐴  =  𝐵  ∧  𝐹  =  𝐺 )  →  { 𝑓  ∣  ∃ 𝑥 ( 𝑓  Fn  𝑥  ∧  ( 𝑥  ⊆  𝐴  ∧  ∀ 𝑦  ∈  𝑥 Pred ( 𝑅 ,  𝐴 ,  𝑦 )  ⊆  𝑥 )  ∧  ∀ 𝑦  ∈  𝑥 ( 𝑓 ‘ 𝑦 )  =  ( 𝐹 ‘ ( 𝑓  ↾  Pred ( 𝑅 ,  𝐴 ,  𝑦 ) ) ) ) }  =  { 𝑓  ∣  ∃ 𝑥 ( 𝑓  Fn  𝑥  ∧  ( 𝑥  ⊆  𝐵  ∧  ∀ 𝑦  ∈  𝑥 Pred ( 𝑆 ,  𝐵 ,  𝑦 )  ⊆  𝑥 )  ∧  ∀ 𝑦  ∈  𝑥 ( 𝑓 ‘ 𝑦 )  =  ( 𝐺 ‘ ( 𝑓  ↾  Pred ( 𝑆 ,  𝐵 ,  𝑦 ) ) ) ) } ) | 
						
							| 19 | 18 | unieqd | ⊢ ( ( 𝑅  =  𝑆  ∧  𝐴  =  𝐵  ∧  𝐹  =  𝐺 )  →  ∪  { 𝑓  ∣  ∃ 𝑥 ( 𝑓  Fn  𝑥  ∧  ( 𝑥  ⊆  𝐴  ∧  ∀ 𝑦  ∈  𝑥 Pred ( 𝑅 ,  𝐴 ,  𝑦 )  ⊆  𝑥 )  ∧  ∀ 𝑦  ∈  𝑥 ( 𝑓 ‘ 𝑦 )  =  ( 𝐹 ‘ ( 𝑓  ↾  Pred ( 𝑅 ,  𝐴 ,  𝑦 ) ) ) ) }  =  ∪  { 𝑓  ∣  ∃ 𝑥 ( 𝑓  Fn  𝑥  ∧  ( 𝑥  ⊆  𝐵  ∧  ∀ 𝑦  ∈  𝑥 Pred ( 𝑆 ,  𝐵 ,  𝑦 )  ⊆  𝑥 )  ∧  ∀ 𝑦  ∈  𝑥 ( 𝑓 ‘ 𝑦 )  =  ( 𝐺 ‘ ( 𝑓  ↾  Pred ( 𝑆 ,  𝐵 ,  𝑦 ) ) ) ) } ) | 
						
							| 20 |  | dfwrecsOLD | ⊢ wrecs ( 𝑅 ,  𝐴 ,  𝐹 )  =  ∪  { 𝑓  ∣  ∃ 𝑥 ( 𝑓  Fn  𝑥  ∧  ( 𝑥  ⊆  𝐴  ∧  ∀ 𝑦  ∈  𝑥 Pred ( 𝑅 ,  𝐴 ,  𝑦 )  ⊆  𝑥 )  ∧  ∀ 𝑦  ∈  𝑥 ( 𝑓 ‘ 𝑦 )  =  ( 𝐹 ‘ ( 𝑓  ↾  Pred ( 𝑅 ,  𝐴 ,  𝑦 ) ) ) ) } | 
						
							| 21 |  | dfwrecsOLD | ⊢ wrecs ( 𝑆 ,  𝐵 ,  𝐺 )  =  ∪  { 𝑓  ∣  ∃ 𝑥 ( 𝑓  Fn  𝑥  ∧  ( 𝑥  ⊆  𝐵  ∧  ∀ 𝑦  ∈  𝑥 Pred ( 𝑆 ,  𝐵 ,  𝑦 )  ⊆  𝑥 )  ∧  ∀ 𝑦  ∈  𝑥 ( 𝑓 ‘ 𝑦 )  =  ( 𝐺 ‘ ( 𝑓  ↾  Pred ( 𝑆 ,  𝐵 ,  𝑦 ) ) ) ) } | 
						
							| 22 | 19 20 21 | 3eqtr4g | ⊢ ( ( 𝑅  =  𝑆  ∧  𝐴  =  𝐵  ∧  𝐹  =  𝐺 )  →  wrecs ( 𝑅 ,  𝐴 ,  𝐹 )  =  wrecs ( 𝑆 ,  𝐵 ,  𝐺 ) ) |