| Step | Hyp | Ref | Expression | 
						
							| 0 |  | cnegs | ⊢  -us | 
						
							| 1 |  | vx | ⊢ 𝑥 | 
						
							| 2 |  | cvv | ⊢ V | 
						
							| 3 |  | vn | ⊢ 𝑛 | 
						
							| 4 | 3 | cv | ⊢ 𝑛 | 
						
							| 5 |  | cright | ⊢  R | 
						
							| 6 | 1 | cv | ⊢ 𝑥 | 
						
							| 7 | 6 5 | cfv | ⊢ (  R  ‘ 𝑥 ) | 
						
							| 8 | 4 7 | cima | ⊢ ( 𝑛  “  (  R  ‘ 𝑥 ) ) | 
						
							| 9 |  | cscut | ⊢  |s | 
						
							| 10 |  | cleft | ⊢  L | 
						
							| 11 | 6 10 | cfv | ⊢ (  L  ‘ 𝑥 ) | 
						
							| 12 | 4 11 | cima | ⊢ ( 𝑛  “  (  L  ‘ 𝑥 ) ) | 
						
							| 13 | 8 12 9 | co | ⊢ ( ( 𝑛  “  (  R  ‘ 𝑥 ) )  |s  ( 𝑛  “  (  L  ‘ 𝑥 ) ) ) | 
						
							| 14 | 1 3 2 2 13 | cmpo | ⊢ ( 𝑥  ∈  V ,  𝑛  ∈  V  ↦  ( ( 𝑛  “  (  R  ‘ 𝑥 ) )  |s  ( 𝑛  “  (  L  ‘ 𝑥 ) ) ) ) | 
						
							| 15 | 14 | cnorec | ⊢  norec  ( ( 𝑥  ∈  V ,  𝑛  ∈  V  ↦  ( ( 𝑛  “  (  R  ‘ 𝑥 ) )  |s  ( 𝑛  “  (  L  ‘ 𝑥 ) ) ) ) ) | 
						
							| 16 | 0 15 | wceq | ⊢  -us   =   norec  ( ( 𝑥  ∈  V ,  𝑛  ∈  V  ↦  ( ( 𝑛  “  (  R  ‘ 𝑥 ) )  |s  ( 𝑛  “  (  L  ‘ 𝑥 ) ) ) ) ) |