| Step | Hyp | Ref | Expression | 
						
							| 1 |  | sseq1 | ⊢ ( 𝐴  =  if ( 𝐴  ∈   Cℋ  ,  𝐴 ,   ℋ )  →  ( 𝐴  ⊆  𝐵  ↔  if ( 𝐴  ∈   Cℋ  ,  𝐴 ,   ℋ )  ⊆  𝐵 ) ) | 
						
							| 2 | 1 | notbid | ⊢ ( 𝐴  =  if ( 𝐴  ∈   Cℋ  ,  𝐴 ,   ℋ )  →  ( ¬  𝐴  ⊆  𝐵  ↔  ¬  if ( 𝐴  ∈   Cℋ  ,  𝐴 ,   ℋ )  ⊆  𝐵 ) ) | 
						
							| 3 |  | sseq2 | ⊢ ( 𝐴  =  if ( 𝐴  ∈   Cℋ  ,  𝐴 ,   ℋ )  →  ( 𝑥  ⊆  𝐴  ↔  𝑥  ⊆  if ( 𝐴  ∈   Cℋ  ,  𝐴 ,   ℋ ) ) ) | 
						
							| 4 | 3 | anbi1d | ⊢ ( 𝐴  =  if ( 𝐴  ∈   Cℋ  ,  𝐴 ,   ℋ )  →  ( ( 𝑥  ⊆  𝐴  ∧  ¬  𝑥  ⊆  𝐵 )  ↔  ( 𝑥  ⊆  if ( 𝐴  ∈   Cℋ  ,  𝐴 ,   ℋ )  ∧  ¬  𝑥  ⊆  𝐵 ) ) ) | 
						
							| 5 | 4 | rexbidv | ⊢ ( 𝐴  =  if ( 𝐴  ∈   Cℋ  ,  𝐴 ,   ℋ )  →  ( ∃ 𝑥  ∈  HAtoms ( 𝑥  ⊆  𝐴  ∧  ¬  𝑥  ⊆  𝐵 )  ↔  ∃ 𝑥  ∈  HAtoms ( 𝑥  ⊆  if ( 𝐴  ∈   Cℋ  ,  𝐴 ,   ℋ )  ∧  ¬  𝑥  ⊆  𝐵 ) ) ) | 
						
							| 6 | 2 5 | bibi12d | ⊢ ( 𝐴  =  if ( 𝐴  ∈   Cℋ  ,  𝐴 ,   ℋ )  →  ( ( ¬  𝐴  ⊆  𝐵  ↔  ∃ 𝑥  ∈  HAtoms ( 𝑥  ⊆  𝐴  ∧  ¬  𝑥  ⊆  𝐵 ) )  ↔  ( ¬  if ( 𝐴  ∈   Cℋ  ,  𝐴 ,   ℋ )  ⊆  𝐵  ↔  ∃ 𝑥  ∈  HAtoms ( 𝑥  ⊆  if ( 𝐴  ∈   Cℋ  ,  𝐴 ,   ℋ )  ∧  ¬  𝑥  ⊆  𝐵 ) ) ) ) | 
						
							| 7 |  | sseq2 | ⊢ ( 𝐵  =  if ( 𝐵  ∈   Cℋ  ,  𝐵 ,   ℋ )  →  ( if ( 𝐴  ∈   Cℋ  ,  𝐴 ,   ℋ )  ⊆  𝐵  ↔  if ( 𝐴  ∈   Cℋ  ,  𝐴 ,   ℋ )  ⊆  if ( 𝐵  ∈   Cℋ  ,  𝐵 ,   ℋ ) ) ) | 
						
							| 8 | 7 | notbid | ⊢ ( 𝐵  =  if ( 𝐵  ∈   Cℋ  ,  𝐵 ,   ℋ )  →  ( ¬  if ( 𝐴  ∈   Cℋ  ,  𝐴 ,   ℋ )  ⊆  𝐵  ↔  ¬  if ( 𝐴  ∈   Cℋ  ,  𝐴 ,   ℋ )  ⊆  if ( 𝐵  ∈   Cℋ  ,  𝐵 ,   ℋ ) ) ) | 
						
							| 9 |  | sseq2 | ⊢ ( 𝐵  =  if ( 𝐵  ∈   Cℋ  ,  𝐵 ,   ℋ )  →  ( 𝑥  ⊆  𝐵  ↔  𝑥  ⊆  if ( 𝐵  ∈   Cℋ  ,  𝐵 ,   ℋ ) ) ) | 
						
							| 10 | 9 | notbid | ⊢ ( 𝐵  =  if ( 𝐵  ∈   Cℋ  ,  𝐵 ,   ℋ )  →  ( ¬  𝑥  ⊆  𝐵  ↔  ¬  𝑥  ⊆  if ( 𝐵  ∈   Cℋ  ,  𝐵 ,   ℋ ) ) ) | 
						
							| 11 | 10 | anbi2d | ⊢ ( 𝐵  =  if ( 𝐵  ∈   Cℋ  ,  𝐵 ,   ℋ )  →  ( ( 𝑥  ⊆  if ( 𝐴  ∈   Cℋ  ,  𝐴 ,   ℋ )  ∧  ¬  𝑥  ⊆  𝐵 )  ↔  ( 𝑥  ⊆  if ( 𝐴  ∈   Cℋ  ,  𝐴 ,   ℋ )  ∧  ¬  𝑥  ⊆  if ( 𝐵  ∈   Cℋ  ,  𝐵 ,   ℋ ) ) ) ) | 
						
							| 12 | 11 | rexbidv | ⊢ ( 𝐵  =  if ( 𝐵  ∈   Cℋ  ,  𝐵 ,   ℋ )  →  ( ∃ 𝑥  ∈  HAtoms ( 𝑥  ⊆  if ( 𝐴  ∈   Cℋ  ,  𝐴 ,   ℋ )  ∧  ¬  𝑥  ⊆  𝐵 )  ↔  ∃ 𝑥  ∈  HAtoms ( 𝑥  ⊆  if ( 𝐴  ∈   Cℋ  ,  𝐴 ,   ℋ )  ∧  ¬  𝑥  ⊆  if ( 𝐵  ∈   Cℋ  ,  𝐵 ,   ℋ ) ) ) ) | 
						
							| 13 | 8 12 | bibi12d | ⊢ ( 𝐵  =  if ( 𝐵  ∈   Cℋ  ,  𝐵 ,   ℋ )  →  ( ( ¬  if ( 𝐴  ∈   Cℋ  ,  𝐴 ,   ℋ )  ⊆  𝐵  ↔  ∃ 𝑥  ∈  HAtoms ( 𝑥  ⊆  if ( 𝐴  ∈   Cℋ  ,  𝐴 ,   ℋ )  ∧  ¬  𝑥  ⊆  𝐵 ) )  ↔  ( ¬  if ( 𝐴  ∈   Cℋ  ,  𝐴 ,   ℋ )  ⊆  if ( 𝐵  ∈   Cℋ  ,  𝐵 ,   ℋ )  ↔  ∃ 𝑥  ∈  HAtoms ( 𝑥  ⊆  if ( 𝐴  ∈   Cℋ  ,  𝐴 ,   ℋ )  ∧  ¬  𝑥  ⊆  if ( 𝐵  ∈   Cℋ  ,  𝐵 ,   ℋ ) ) ) ) ) | 
						
							| 14 |  | ifchhv | ⊢ if ( 𝐴  ∈   Cℋ  ,  𝐴 ,   ℋ )  ∈   Cℋ | 
						
							| 15 |  | ifchhv | ⊢ if ( 𝐵  ∈   Cℋ  ,  𝐵 ,   ℋ )  ∈   Cℋ | 
						
							| 16 | 14 15 | chrelat2i | ⊢ ( ¬  if ( 𝐴  ∈   Cℋ  ,  𝐴 ,   ℋ )  ⊆  if ( 𝐵  ∈   Cℋ  ,  𝐵 ,   ℋ )  ↔  ∃ 𝑥  ∈  HAtoms ( 𝑥  ⊆  if ( 𝐴  ∈   Cℋ  ,  𝐴 ,   ℋ )  ∧  ¬  𝑥  ⊆  if ( 𝐵  ∈   Cℋ  ,  𝐵 ,   ℋ ) ) ) | 
						
							| 17 | 6 13 16 | dedth2h | ⊢ ( ( 𝐴  ∈   Cℋ   ∧  𝐵  ∈   Cℋ  )  →  ( ¬  𝐴  ⊆  𝐵  ↔  ∃ 𝑥  ∈  HAtoms ( 𝑥  ⊆  𝐴  ∧  ¬  𝑥  ⊆  𝐵 ) ) ) |