| Step | Hyp | Ref | Expression | 
						
							| 1 |  | ima0 | ⊢ ( ( 𝑅  ∖  ( 𝐴  ×  𝐵 ) )  “  ∅ )  =  ∅ | 
						
							| 2 |  | imaeq2 | ⊢ ( 𝐶  =  ∅  →  ( ( 𝑅  ∖  ( 𝐴  ×  𝐵 ) )  “  𝐶 )  =  ( ( 𝑅  ∖  ( 𝐴  ×  𝐵 ) )  “  ∅ ) ) | 
						
							| 3 |  | imaeq2 | ⊢ ( 𝐶  =  ∅  →  ( 𝑅  “  𝐶 )  =  ( 𝑅  “  ∅ ) ) | 
						
							| 4 |  | ima0 | ⊢ ( 𝑅  “  ∅ )  =  ∅ | 
						
							| 5 | 3 4 | eqtrdi | ⊢ ( 𝐶  =  ∅  →  ( 𝑅  “  𝐶 )  =  ∅ ) | 
						
							| 6 | 5 | difeq1d | ⊢ ( 𝐶  =  ∅  →  ( ( 𝑅  “  𝐶 )  ∖  𝐵 )  =  ( ∅  ∖  𝐵 ) ) | 
						
							| 7 |  | 0dif | ⊢ ( ∅  ∖  𝐵 )  =  ∅ | 
						
							| 8 | 6 7 | eqtrdi | ⊢ ( 𝐶  =  ∅  →  ( ( 𝑅  “  𝐶 )  ∖  𝐵 )  =  ∅ ) | 
						
							| 9 | 1 2 8 | 3eqtr4a | ⊢ ( 𝐶  =  ∅  →  ( ( 𝑅  ∖  ( 𝐴  ×  𝐵 ) )  “  𝐶 )  =  ( ( 𝑅  “  𝐶 )  ∖  𝐵 ) ) | 
						
							| 10 | 9 | adantl | ⊢ ( ( 𝐶  ⊆  𝐴  ∧  𝐶  =  ∅ )  →  ( ( 𝑅  ∖  ( 𝐴  ×  𝐵 ) )  “  𝐶 )  =  ( ( 𝑅  “  𝐶 )  ∖  𝐵 ) ) | 
						
							| 11 |  | uncom | ⊢ ( ∅  ∪  ( ( 𝑅  ∖  ( 𝐴  ×  𝐵 ) )  “  𝐶 ) )  =  ( ( ( 𝑅  ∖  ( 𝐴  ×  𝐵 ) )  “  𝐶 )  ∪  ∅ ) | 
						
							| 12 |  | un0 | ⊢ ( ( ( 𝑅  ∖  ( 𝐴  ×  𝐵 ) )  “  𝐶 )  ∪  ∅ )  =  ( ( 𝑅  ∖  ( 𝐴  ×  𝐵 ) )  “  𝐶 ) | 
						
							| 13 | 11 12 | eqtr2i | ⊢ ( ( 𝑅  ∖  ( 𝐴  ×  𝐵 ) )  “  𝐶 )  =  ( ∅  ∪  ( ( 𝑅  ∖  ( 𝐴  ×  𝐵 ) )  “  𝐶 ) ) | 
						
							| 14 |  | inundif | ⊢ ( ( 𝑅  ∩  ( 𝐴  ×  𝐵 ) )  ∪  ( 𝑅  ∖  ( 𝐴  ×  𝐵 ) ) )  =  𝑅 | 
						
							| 15 | 14 | imaeq1i | ⊢ ( ( ( 𝑅  ∩  ( 𝐴  ×  𝐵 ) )  ∪  ( 𝑅  ∖  ( 𝐴  ×  𝐵 ) ) )  “  𝐶 )  =  ( 𝑅  “  𝐶 ) | 
						
							| 16 |  | imaundir | ⊢ ( ( ( 𝑅  ∩  ( 𝐴  ×  𝐵 ) )  ∪  ( 𝑅  ∖  ( 𝐴  ×  𝐵 ) ) )  “  𝐶 )  =  ( ( ( 𝑅  ∩  ( 𝐴  ×  𝐵 ) )  “  𝐶 )  ∪  ( ( 𝑅  ∖  ( 𝐴  ×  𝐵 ) )  “  𝐶 ) ) | 
						
							| 17 | 15 16 | eqtr3i | ⊢ ( 𝑅  “  𝐶 )  =  ( ( ( 𝑅  ∩  ( 𝐴  ×  𝐵 ) )  “  𝐶 )  ∪  ( ( 𝑅  ∖  ( 𝐴  ×  𝐵 ) )  “  𝐶 ) ) | 
						
							| 18 | 17 | difeq1i | ⊢ ( ( 𝑅  “  𝐶 )  ∖  𝐵 )  =  ( ( ( ( 𝑅  ∩  ( 𝐴  ×  𝐵 ) )  “  𝐶 )  ∪  ( ( 𝑅  ∖  ( 𝐴  ×  𝐵 ) )  “  𝐶 ) )  ∖  𝐵 ) | 
						
							| 19 |  | difundir | ⊢ ( ( ( ( 𝑅  ∩  ( 𝐴  ×  𝐵 ) )  “  𝐶 )  ∪  ( ( 𝑅  ∖  ( 𝐴  ×  𝐵 ) )  “  𝐶 ) )  ∖  𝐵 )  =  ( ( ( ( 𝑅  ∩  ( 𝐴  ×  𝐵 ) )  “  𝐶 )  ∖  𝐵 )  ∪  ( ( ( 𝑅  ∖  ( 𝐴  ×  𝐵 ) )  “  𝐶 )  ∖  𝐵 ) ) | 
						
							| 20 | 18 19 | eqtri | ⊢ ( ( 𝑅  “  𝐶 )  ∖  𝐵 )  =  ( ( ( ( 𝑅  ∩  ( 𝐴  ×  𝐵 ) )  “  𝐶 )  ∖  𝐵 )  ∪  ( ( ( 𝑅  ∖  ( 𝐴  ×  𝐵 ) )  “  𝐶 )  ∖  𝐵 ) ) | 
						
							| 21 |  | inss2 | ⊢ ( 𝑅  ∩  ( 𝐴  ×  𝐵 ) )  ⊆  ( 𝐴  ×  𝐵 ) | 
						
							| 22 |  | imass1 | ⊢ ( ( 𝑅  ∩  ( 𝐴  ×  𝐵 ) )  ⊆  ( 𝐴  ×  𝐵 )  →  ( ( 𝑅  ∩  ( 𝐴  ×  𝐵 ) )  “  𝐶 )  ⊆  ( ( 𝐴  ×  𝐵 )  “  𝐶 ) ) | 
						
							| 23 |  | ssdif | ⊢ ( ( ( 𝑅  ∩  ( 𝐴  ×  𝐵 ) )  “  𝐶 )  ⊆  ( ( 𝐴  ×  𝐵 )  “  𝐶 )  →  ( ( ( 𝑅  ∩  ( 𝐴  ×  𝐵 ) )  “  𝐶 )  ∖  𝐵 )  ⊆  ( ( ( 𝐴  ×  𝐵 )  “  𝐶 )  ∖  𝐵 ) ) | 
						
							| 24 | 21 22 23 | mp2b | ⊢ ( ( ( 𝑅  ∩  ( 𝐴  ×  𝐵 ) )  “  𝐶 )  ∖  𝐵 )  ⊆  ( ( ( 𝐴  ×  𝐵 )  “  𝐶 )  ∖  𝐵 ) | 
						
							| 25 |  | xpima | ⊢ ( ( 𝐴  ×  𝐵 )  “  𝐶 )  =  if ( ( 𝐴  ∩  𝐶 )  =  ∅ ,  ∅ ,  𝐵 ) | 
						
							| 26 |  | incom | ⊢ ( 𝐶  ∩  𝐴 )  =  ( 𝐴  ∩  𝐶 ) | 
						
							| 27 |  | dfss2 | ⊢ ( 𝐶  ⊆  𝐴  ↔  ( 𝐶  ∩  𝐴 )  =  𝐶 ) | 
						
							| 28 | 27 | biimpi | ⊢ ( 𝐶  ⊆  𝐴  →  ( 𝐶  ∩  𝐴 )  =  𝐶 ) | 
						
							| 29 | 26 28 | eqtr3id | ⊢ ( 𝐶  ⊆  𝐴  →  ( 𝐴  ∩  𝐶 )  =  𝐶 ) | 
						
							| 30 | 29 | adantl | ⊢ ( ( 𝐶  ≠  ∅  ∧  𝐶  ⊆  𝐴 )  →  ( 𝐴  ∩  𝐶 )  =  𝐶 ) | 
						
							| 31 |  | simpl | ⊢ ( ( 𝐶  ≠  ∅  ∧  𝐶  ⊆  𝐴 )  →  𝐶  ≠  ∅ ) | 
						
							| 32 | 30 31 | eqnetrd | ⊢ ( ( 𝐶  ≠  ∅  ∧  𝐶  ⊆  𝐴 )  →  ( 𝐴  ∩  𝐶 )  ≠  ∅ ) | 
						
							| 33 |  | neneq | ⊢ ( ( 𝐴  ∩  𝐶 )  ≠  ∅  →  ¬  ( 𝐴  ∩  𝐶 )  =  ∅ ) | 
						
							| 34 |  | iffalse | ⊢ ( ¬  ( 𝐴  ∩  𝐶 )  =  ∅  →  if ( ( 𝐴  ∩  𝐶 )  =  ∅ ,  ∅ ,  𝐵 )  =  𝐵 ) | 
						
							| 35 | 32 33 34 | 3syl | ⊢ ( ( 𝐶  ≠  ∅  ∧  𝐶  ⊆  𝐴 )  →  if ( ( 𝐴  ∩  𝐶 )  =  ∅ ,  ∅ ,  𝐵 )  =  𝐵 ) | 
						
							| 36 | 25 35 | eqtrid | ⊢ ( ( 𝐶  ≠  ∅  ∧  𝐶  ⊆  𝐴 )  →  ( ( 𝐴  ×  𝐵 )  “  𝐶 )  =  𝐵 ) | 
						
							| 37 | 36 | difeq1d | ⊢ ( ( 𝐶  ≠  ∅  ∧  𝐶  ⊆  𝐴 )  →  ( ( ( 𝐴  ×  𝐵 )  “  𝐶 )  ∖  𝐵 )  =  ( 𝐵  ∖  𝐵 ) ) | 
						
							| 38 |  | difid | ⊢ ( 𝐵  ∖  𝐵 )  =  ∅ | 
						
							| 39 | 37 38 | eqtrdi | ⊢ ( ( 𝐶  ≠  ∅  ∧  𝐶  ⊆  𝐴 )  →  ( ( ( 𝐴  ×  𝐵 )  “  𝐶 )  ∖  𝐵 )  =  ∅ ) | 
						
							| 40 | 24 39 | sseqtrid | ⊢ ( ( 𝐶  ≠  ∅  ∧  𝐶  ⊆  𝐴 )  →  ( ( ( 𝑅  ∩  ( 𝐴  ×  𝐵 ) )  “  𝐶 )  ∖  𝐵 )  ⊆  ∅ ) | 
						
							| 41 |  | ss0 | ⊢ ( ( ( ( 𝑅  ∩  ( 𝐴  ×  𝐵 ) )  “  𝐶 )  ∖  𝐵 )  ⊆  ∅  →  ( ( ( 𝑅  ∩  ( 𝐴  ×  𝐵 ) )  “  𝐶 )  ∖  𝐵 )  =  ∅ ) | 
						
							| 42 | 40 41 | syl | ⊢ ( ( 𝐶  ≠  ∅  ∧  𝐶  ⊆  𝐴 )  →  ( ( ( 𝑅  ∩  ( 𝐴  ×  𝐵 ) )  “  𝐶 )  ∖  𝐵 )  =  ∅ ) | 
						
							| 43 |  | df-ima | ⊢ ( ( 𝑅  ∖  ( 𝐴  ×  𝐵 ) )  “  𝐶 )  =  ran  ( ( 𝑅  ∖  ( 𝐴  ×  𝐵 ) )  ↾  𝐶 ) | 
						
							| 44 |  | df-res | ⊢ ( ( 𝑅  ∖  ( 𝐴  ×  𝐵 ) )  ↾  𝐶 )  =  ( ( 𝑅  ∖  ( 𝐴  ×  𝐵 ) )  ∩  ( 𝐶  ×  V ) ) | 
						
							| 45 | 44 | rneqi | ⊢ ran  ( ( 𝑅  ∖  ( 𝐴  ×  𝐵 ) )  ↾  𝐶 )  =  ran  ( ( 𝑅  ∖  ( 𝐴  ×  𝐵 ) )  ∩  ( 𝐶  ×  V ) ) | 
						
							| 46 | 43 45 | eqtri | ⊢ ( ( 𝑅  ∖  ( 𝐴  ×  𝐵 ) )  “  𝐶 )  =  ran  ( ( 𝑅  ∖  ( 𝐴  ×  𝐵 ) )  ∩  ( 𝐶  ×  V ) ) | 
						
							| 47 | 46 | ineq1i | ⊢ ( ( ( 𝑅  ∖  ( 𝐴  ×  𝐵 ) )  “  𝐶 )  ∩  𝐵 )  =  ( ran  ( ( 𝑅  ∖  ( 𝐴  ×  𝐵 ) )  ∩  ( 𝐶  ×  V ) )  ∩  𝐵 ) | 
						
							| 48 |  | xpss1 | ⊢ ( 𝐶  ⊆  𝐴  →  ( 𝐶  ×  V )  ⊆  ( 𝐴  ×  V ) ) | 
						
							| 49 |  | sslin | ⊢ ( ( 𝐶  ×  V )  ⊆  ( 𝐴  ×  V )  →  ( ( 𝑅  ∖  ( 𝐴  ×  𝐵 ) )  ∩  ( 𝐶  ×  V ) )  ⊆  ( ( 𝑅  ∖  ( 𝐴  ×  𝐵 ) )  ∩  ( 𝐴  ×  V ) ) ) | 
						
							| 50 |  | rnss | ⊢ ( ( ( 𝑅  ∖  ( 𝐴  ×  𝐵 ) )  ∩  ( 𝐶  ×  V ) )  ⊆  ( ( 𝑅  ∖  ( 𝐴  ×  𝐵 ) )  ∩  ( 𝐴  ×  V ) )  →  ran  ( ( 𝑅  ∖  ( 𝐴  ×  𝐵 ) )  ∩  ( 𝐶  ×  V ) )  ⊆  ran  ( ( 𝑅  ∖  ( 𝐴  ×  𝐵 ) )  ∩  ( 𝐴  ×  V ) ) ) | 
						
							| 51 | 48 49 50 | 3syl | ⊢ ( 𝐶  ⊆  𝐴  →  ran  ( ( 𝑅  ∖  ( 𝐴  ×  𝐵 ) )  ∩  ( 𝐶  ×  V ) )  ⊆  ran  ( ( 𝑅  ∖  ( 𝐴  ×  𝐵 ) )  ∩  ( 𝐴  ×  V ) ) ) | 
						
							| 52 |  | ssn0 | ⊢ ( ( 𝐶  ⊆  𝐴  ∧  𝐶  ≠  ∅ )  →  𝐴  ≠  ∅ ) | 
						
							| 53 | 52 | ancoms | ⊢ ( ( 𝐶  ≠  ∅  ∧  𝐶  ⊆  𝐴 )  →  𝐴  ≠  ∅ ) | 
						
							| 54 |  | inss1 | ⊢ ( ( 𝐴  ×  V )  ∩  𝑅 )  ⊆  ( 𝐴  ×  V ) | 
						
							| 55 |  | ssdif | ⊢ ( ( ( 𝐴  ×  V )  ∩  𝑅 )  ⊆  ( 𝐴  ×  V )  →  ( ( ( 𝐴  ×  V )  ∩  𝑅 )  ∖  ( 𝐴  ×  𝐵 ) )  ⊆  ( ( 𝐴  ×  V )  ∖  ( 𝐴  ×  𝐵 ) ) ) | 
						
							| 56 | 54 55 | ax-mp | ⊢ ( ( ( 𝐴  ×  V )  ∩  𝑅 )  ∖  ( 𝐴  ×  𝐵 ) )  ⊆  ( ( 𝐴  ×  V )  ∖  ( 𝐴  ×  𝐵 ) ) | 
						
							| 57 |  | incom | ⊢ ( ( 𝐴  ×  V )  ∩  ( 𝑅  ∖  ( 𝐴  ×  𝐵 ) ) )  =  ( ( 𝑅  ∖  ( 𝐴  ×  𝐵 ) )  ∩  ( 𝐴  ×  V ) ) | 
						
							| 58 |  | indif2 | ⊢ ( ( 𝐴  ×  V )  ∩  ( 𝑅  ∖  ( 𝐴  ×  𝐵 ) ) )  =  ( ( ( 𝐴  ×  V )  ∩  𝑅 )  ∖  ( 𝐴  ×  𝐵 ) ) | 
						
							| 59 | 57 58 | eqtr3i | ⊢ ( ( 𝑅  ∖  ( 𝐴  ×  𝐵 ) )  ∩  ( 𝐴  ×  V ) )  =  ( ( ( 𝐴  ×  V )  ∩  𝑅 )  ∖  ( 𝐴  ×  𝐵 ) ) | 
						
							| 60 |  | difxp2 | ⊢ ( 𝐴  ×  ( V  ∖  𝐵 ) )  =  ( ( 𝐴  ×  V )  ∖  ( 𝐴  ×  𝐵 ) ) | 
						
							| 61 | 56 59 60 | 3sstr4i | ⊢ ( ( 𝑅  ∖  ( 𝐴  ×  𝐵 ) )  ∩  ( 𝐴  ×  V ) )  ⊆  ( 𝐴  ×  ( V  ∖  𝐵 ) ) | 
						
							| 62 |  | rnss | ⊢ ( ( ( 𝑅  ∖  ( 𝐴  ×  𝐵 ) )  ∩  ( 𝐴  ×  V ) )  ⊆  ( 𝐴  ×  ( V  ∖  𝐵 ) )  →  ran  ( ( 𝑅  ∖  ( 𝐴  ×  𝐵 ) )  ∩  ( 𝐴  ×  V ) )  ⊆  ran  ( 𝐴  ×  ( V  ∖  𝐵 ) ) ) | 
						
							| 63 | 61 62 | mp1i | ⊢ ( 𝐴  ≠  ∅  →  ran  ( ( 𝑅  ∖  ( 𝐴  ×  𝐵 ) )  ∩  ( 𝐴  ×  V ) )  ⊆  ran  ( 𝐴  ×  ( V  ∖  𝐵 ) ) ) | 
						
							| 64 |  | rnxp | ⊢ ( 𝐴  ≠  ∅  →  ran  ( 𝐴  ×  ( V  ∖  𝐵 ) )  =  ( V  ∖  𝐵 ) ) | 
						
							| 65 | 63 64 | sseqtrd | ⊢ ( 𝐴  ≠  ∅  →  ran  ( ( 𝑅  ∖  ( 𝐴  ×  𝐵 ) )  ∩  ( 𝐴  ×  V ) )  ⊆  ( V  ∖  𝐵 ) ) | 
						
							| 66 |  | disj2 | ⊢ ( ( ran  ( ( 𝑅  ∖  ( 𝐴  ×  𝐵 ) )  ∩  ( 𝐴  ×  V ) )  ∩  𝐵 )  =  ∅  ↔  ran  ( ( 𝑅  ∖  ( 𝐴  ×  𝐵 ) )  ∩  ( 𝐴  ×  V ) )  ⊆  ( V  ∖  𝐵 ) ) | 
						
							| 67 | 65 66 | sylibr | ⊢ ( 𝐴  ≠  ∅  →  ( ran  ( ( 𝑅  ∖  ( 𝐴  ×  𝐵 ) )  ∩  ( 𝐴  ×  V ) )  ∩  𝐵 )  =  ∅ ) | 
						
							| 68 | 53 67 | syl | ⊢ ( ( 𝐶  ≠  ∅  ∧  𝐶  ⊆  𝐴 )  →  ( ran  ( ( 𝑅  ∖  ( 𝐴  ×  𝐵 ) )  ∩  ( 𝐴  ×  V ) )  ∩  𝐵 )  =  ∅ ) | 
						
							| 69 |  | ssdisj | ⊢ ( ( ran  ( ( 𝑅  ∖  ( 𝐴  ×  𝐵 ) )  ∩  ( 𝐶  ×  V ) )  ⊆  ran  ( ( 𝑅  ∖  ( 𝐴  ×  𝐵 ) )  ∩  ( 𝐴  ×  V ) )  ∧  ( ran  ( ( 𝑅  ∖  ( 𝐴  ×  𝐵 ) )  ∩  ( 𝐴  ×  V ) )  ∩  𝐵 )  =  ∅ )  →  ( ran  ( ( 𝑅  ∖  ( 𝐴  ×  𝐵 ) )  ∩  ( 𝐶  ×  V ) )  ∩  𝐵 )  =  ∅ ) | 
						
							| 70 | 51 68 69 | syl2an2 | ⊢ ( ( 𝐶  ≠  ∅  ∧  𝐶  ⊆  𝐴 )  →  ( ran  ( ( 𝑅  ∖  ( 𝐴  ×  𝐵 ) )  ∩  ( 𝐶  ×  V ) )  ∩  𝐵 )  =  ∅ ) | 
						
							| 71 | 47 70 | eqtrid | ⊢ ( ( 𝐶  ≠  ∅  ∧  𝐶  ⊆  𝐴 )  →  ( ( ( 𝑅  ∖  ( 𝐴  ×  𝐵 ) )  “  𝐶 )  ∩  𝐵 )  =  ∅ ) | 
						
							| 72 |  | disj3 | ⊢ ( ( ( ( 𝑅  ∖  ( 𝐴  ×  𝐵 ) )  “  𝐶 )  ∩  𝐵 )  =  ∅  ↔  ( ( 𝑅  ∖  ( 𝐴  ×  𝐵 ) )  “  𝐶 )  =  ( ( ( 𝑅  ∖  ( 𝐴  ×  𝐵 ) )  “  𝐶 )  ∖  𝐵 ) ) | 
						
							| 73 | 71 72 | sylib | ⊢ ( ( 𝐶  ≠  ∅  ∧  𝐶  ⊆  𝐴 )  →  ( ( 𝑅  ∖  ( 𝐴  ×  𝐵 ) )  “  𝐶 )  =  ( ( ( 𝑅  ∖  ( 𝐴  ×  𝐵 ) )  “  𝐶 )  ∖  𝐵 ) ) | 
						
							| 74 | 73 | eqcomd | ⊢ ( ( 𝐶  ≠  ∅  ∧  𝐶  ⊆  𝐴 )  →  ( ( ( 𝑅  ∖  ( 𝐴  ×  𝐵 ) )  “  𝐶 )  ∖  𝐵 )  =  ( ( 𝑅  ∖  ( 𝐴  ×  𝐵 ) )  “  𝐶 ) ) | 
						
							| 75 | 42 74 | uneq12d | ⊢ ( ( 𝐶  ≠  ∅  ∧  𝐶  ⊆  𝐴 )  →  ( ( ( ( 𝑅  ∩  ( 𝐴  ×  𝐵 ) )  “  𝐶 )  ∖  𝐵 )  ∪  ( ( ( 𝑅  ∖  ( 𝐴  ×  𝐵 ) )  “  𝐶 )  ∖  𝐵 ) )  =  ( ∅  ∪  ( ( 𝑅  ∖  ( 𝐴  ×  𝐵 ) )  “  𝐶 ) ) ) | 
						
							| 76 | 20 75 | eqtrid | ⊢ ( ( 𝐶  ≠  ∅  ∧  𝐶  ⊆  𝐴 )  →  ( ( 𝑅  “  𝐶 )  ∖  𝐵 )  =  ( ∅  ∪  ( ( 𝑅  ∖  ( 𝐴  ×  𝐵 ) )  “  𝐶 ) ) ) | 
						
							| 77 | 13 76 | eqtr4id | ⊢ ( ( 𝐶  ≠  ∅  ∧  𝐶  ⊆  𝐴 )  →  ( ( 𝑅  ∖  ( 𝐴  ×  𝐵 ) )  “  𝐶 )  =  ( ( 𝑅  “  𝐶 )  ∖  𝐵 ) ) | 
						
							| 78 | 77 | ancoms | ⊢ ( ( 𝐶  ⊆  𝐴  ∧  𝐶  ≠  ∅ )  →  ( ( 𝑅  ∖  ( 𝐴  ×  𝐵 ) )  “  𝐶 )  =  ( ( 𝑅  “  𝐶 )  ∖  𝐵 ) ) | 
						
							| 79 | 10 78 | pm2.61dane | ⊢ ( 𝐶  ⊆  𝐴  →  ( ( 𝑅  ∖  ( 𝐴  ×  𝐵 ) )  “  𝐶 )  =  ( ( 𝑅  “  𝐶 )  ∖  𝐵 ) ) |