| Step | Hyp | Ref | Expression | 
						
							| 1 |  | difss | ⊢ ( ( ( 𝐺  ∘  𝐹 )  ∘  ◡ 𝐺 )  ∖   I  )  ⊆  ( ( 𝐺  ∘  𝐹 )  ∘  ◡ 𝐺 ) | 
						
							| 2 |  | dmss | ⊢ ( ( ( ( 𝐺  ∘  𝐹 )  ∘  ◡ 𝐺 )  ∖   I  )  ⊆  ( ( 𝐺  ∘  𝐹 )  ∘  ◡ 𝐺 )  →  dom  ( ( ( 𝐺  ∘  𝐹 )  ∘  ◡ 𝐺 )  ∖   I  )  ⊆  dom  ( ( 𝐺  ∘  𝐹 )  ∘  ◡ 𝐺 ) ) | 
						
							| 3 | 1 2 | ax-mp | ⊢ dom  ( ( ( 𝐺  ∘  𝐹 )  ∘  ◡ 𝐺 )  ∖   I  )  ⊆  dom  ( ( 𝐺  ∘  𝐹 )  ∘  ◡ 𝐺 ) | 
						
							| 4 |  | dmcoss | ⊢ dom  ( ( 𝐺  ∘  𝐹 )  ∘  ◡ 𝐺 )  ⊆  dom  ◡ 𝐺 | 
						
							| 5 | 3 4 | sstri | ⊢ dom  ( ( ( 𝐺  ∘  𝐹 )  ∘  ◡ 𝐺 )  ∖   I  )  ⊆  dom  ◡ 𝐺 | 
						
							| 6 |  | f1ocnv | ⊢ ( 𝐺 : 𝐴 –1-1-onto→ 𝐴  →  ◡ 𝐺 : 𝐴 –1-1-onto→ 𝐴 ) | 
						
							| 7 | 6 | adantl | ⊢ ( ( 𝐹 : 𝐴 ⟶ 𝐴  ∧  𝐺 : 𝐴 –1-1-onto→ 𝐴 )  →  ◡ 𝐺 : 𝐴 –1-1-onto→ 𝐴 ) | 
						
							| 8 |  | f1odm | ⊢ ( ◡ 𝐺 : 𝐴 –1-1-onto→ 𝐴  →  dom  ◡ 𝐺  =  𝐴 ) | 
						
							| 9 | 7 8 | syl | ⊢ ( ( 𝐹 : 𝐴 ⟶ 𝐴  ∧  𝐺 : 𝐴 –1-1-onto→ 𝐴 )  →  dom  ◡ 𝐺  =  𝐴 ) | 
						
							| 10 | 5 9 | sseqtrid | ⊢ ( ( 𝐹 : 𝐴 ⟶ 𝐴  ∧  𝐺 : 𝐴 –1-1-onto→ 𝐴 )  →  dom  ( ( ( 𝐺  ∘  𝐹 )  ∘  ◡ 𝐺 )  ∖   I  )  ⊆  𝐴 ) | 
						
							| 11 | 10 | sselda | ⊢ ( ( ( 𝐹 : 𝐴 ⟶ 𝐴  ∧  𝐺 : 𝐴 –1-1-onto→ 𝐴 )  ∧  𝑥  ∈  dom  ( ( ( 𝐺  ∘  𝐹 )  ∘  ◡ 𝐺 )  ∖   I  ) )  →  𝑥  ∈  𝐴 ) | 
						
							| 12 |  | imassrn | ⊢ ( 𝐺  “  dom  ( 𝐹  ∖   I  ) )  ⊆  ran  𝐺 | 
						
							| 13 |  | f1of | ⊢ ( 𝐺 : 𝐴 –1-1-onto→ 𝐴  →  𝐺 : 𝐴 ⟶ 𝐴 ) | 
						
							| 14 | 13 | adantl | ⊢ ( ( 𝐹 : 𝐴 ⟶ 𝐴  ∧  𝐺 : 𝐴 –1-1-onto→ 𝐴 )  →  𝐺 : 𝐴 ⟶ 𝐴 ) | 
						
							| 15 | 14 | frnd | ⊢ ( ( 𝐹 : 𝐴 ⟶ 𝐴  ∧  𝐺 : 𝐴 –1-1-onto→ 𝐴 )  →  ran  𝐺  ⊆  𝐴 ) | 
						
							| 16 | 12 15 | sstrid | ⊢ ( ( 𝐹 : 𝐴 ⟶ 𝐴  ∧  𝐺 : 𝐴 –1-1-onto→ 𝐴 )  →  ( 𝐺  “  dom  ( 𝐹  ∖   I  ) )  ⊆  𝐴 ) | 
						
							| 17 | 16 | sselda | ⊢ ( ( ( 𝐹 : 𝐴 ⟶ 𝐴  ∧  𝐺 : 𝐴 –1-1-onto→ 𝐴 )  ∧  𝑥  ∈  ( 𝐺  “  dom  ( 𝐹  ∖   I  ) ) )  →  𝑥  ∈  𝐴 ) | 
						
							| 18 |  | simpl | ⊢ ( ( 𝐹 : 𝐴 ⟶ 𝐴  ∧  𝐺 : 𝐴 –1-1-onto→ 𝐴 )  →  𝐹 : 𝐴 ⟶ 𝐴 ) | 
						
							| 19 |  | fco | ⊢ ( ( 𝐺 : 𝐴 ⟶ 𝐴  ∧  𝐹 : 𝐴 ⟶ 𝐴 )  →  ( 𝐺  ∘  𝐹 ) : 𝐴 ⟶ 𝐴 ) | 
						
							| 20 | 14 18 19 | syl2anc | ⊢ ( ( 𝐹 : 𝐴 ⟶ 𝐴  ∧  𝐺 : 𝐴 –1-1-onto→ 𝐴 )  →  ( 𝐺  ∘  𝐹 ) : 𝐴 ⟶ 𝐴 ) | 
						
							| 21 |  | f1of | ⊢ ( ◡ 𝐺 : 𝐴 –1-1-onto→ 𝐴  →  ◡ 𝐺 : 𝐴 ⟶ 𝐴 ) | 
						
							| 22 | 7 21 | syl | ⊢ ( ( 𝐹 : 𝐴 ⟶ 𝐴  ∧  𝐺 : 𝐴 –1-1-onto→ 𝐴 )  →  ◡ 𝐺 : 𝐴 ⟶ 𝐴 ) | 
						
							| 23 |  | fco | ⊢ ( ( ( 𝐺  ∘  𝐹 ) : 𝐴 ⟶ 𝐴  ∧  ◡ 𝐺 : 𝐴 ⟶ 𝐴 )  →  ( ( 𝐺  ∘  𝐹 )  ∘  ◡ 𝐺 ) : 𝐴 ⟶ 𝐴 ) | 
						
							| 24 | 20 22 23 | syl2anc | ⊢ ( ( 𝐹 : 𝐴 ⟶ 𝐴  ∧  𝐺 : 𝐴 –1-1-onto→ 𝐴 )  →  ( ( 𝐺  ∘  𝐹 )  ∘  ◡ 𝐺 ) : 𝐴 ⟶ 𝐴 ) | 
						
							| 25 | 24 | ffnd | ⊢ ( ( 𝐹 : 𝐴 ⟶ 𝐴  ∧  𝐺 : 𝐴 –1-1-onto→ 𝐴 )  →  ( ( 𝐺  ∘  𝐹 )  ∘  ◡ 𝐺 )  Fn  𝐴 ) | 
						
							| 26 |  | fnelnfp | ⊢ ( ( ( ( 𝐺  ∘  𝐹 )  ∘  ◡ 𝐺 )  Fn  𝐴  ∧  𝑥  ∈  𝐴 )  →  ( 𝑥  ∈  dom  ( ( ( 𝐺  ∘  𝐹 )  ∘  ◡ 𝐺 )  ∖   I  )  ↔  ( ( ( 𝐺  ∘  𝐹 )  ∘  ◡ 𝐺 ) ‘ 𝑥 )  ≠  𝑥 ) ) | 
						
							| 27 | 25 26 | sylan | ⊢ ( ( ( 𝐹 : 𝐴 ⟶ 𝐴  ∧  𝐺 : 𝐴 –1-1-onto→ 𝐴 )  ∧  𝑥  ∈  𝐴 )  →  ( 𝑥  ∈  dom  ( ( ( 𝐺  ∘  𝐹 )  ∘  ◡ 𝐺 )  ∖   I  )  ↔  ( ( ( 𝐺  ∘  𝐹 )  ∘  ◡ 𝐺 ) ‘ 𝑥 )  ≠  𝑥 ) ) | 
						
							| 28 |  | f1ofn | ⊢ ( ◡ 𝐺 : 𝐴 –1-1-onto→ 𝐴  →  ◡ 𝐺  Fn  𝐴 ) | 
						
							| 29 | 7 28 | syl | ⊢ ( ( 𝐹 : 𝐴 ⟶ 𝐴  ∧  𝐺 : 𝐴 –1-1-onto→ 𝐴 )  →  ◡ 𝐺  Fn  𝐴 ) | 
						
							| 30 |  | fvco2 | ⊢ ( ( ◡ 𝐺  Fn  𝐴  ∧  𝑥  ∈  𝐴 )  →  ( ( ( 𝐺  ∘  𝐹 )  ∘  ◡ 𝐺 ) ‘ 𝑥 )  =  ( ( 𝐺  ∘  𝐹 ) ‘ ( ◡ 𝐺 ‘ 𝑥 ) ) ) | 
						
							| 31 | 29 30 | sylan | ⊢ ( ( ( 𝐹 : 𝐴 ⟶ 𝐴  ∧  𝐺 : 𝐴 –1-1-onto→ 𝐴 )  ∧  𝑥  ∈  𝐴 )  →  ( ( ( 𝐺  ∘  𝐹 )  ∘  ◡ 𝐺 ) ‘ 𝑥 )  =  ( ( 𝐺  ∘  𝐹 ) ‘ ( ◡ 𝐺 ‘ 𝑥 ) ) ) | 
						
							| 32 |  | ffn | ⊢ ( 𝐹 : 𝐴 ⟶ 𝐴  →  𝐹  Fn  𝐴 ) | 
						
							| 33 | 32 | ad2antrr | ⊢ ( ( ( 𝐹 : 𝐴 ⟶ 𝐴  ∧  𝐺 : 𝐴 –1-1-onto→ 𝐴 )  ∧  𝑥  ∈  𝐴 )  →  𝐹  Fn  𝐴 ) | 
						
							| 34 |  | ffvelcdm | ⊢ ( ( ◡ 𝐺 : 𝐴 ⟶ 𝐴  ∧  𝑥  ∈  𝐴 )  →  ( ◡ 𝐺 ‘ 𝑥 )  ∈  𝐴 ) | 
						
							| 35 | 22 34 | sylan | ⊢ ( ( ( 𝐹 : 𝐴 ⟶ 𝐴  ∧  𝐺 : 𝐴 –1-1-onto→ 𝐴 )  ∧  𝑥  ∈  𝐴 )  →  ( ◡ 𝐺 ‘ 𝑥 )  ∈  𝐴 ) | 
						
							| 36 |  | fvco2 | ⊢ ( ( 𝐹  Fn  𝐴  ∧  ( ◡ 𝐺 ‘ 𝑥 )  ∈  𝐴 )  →  ( ( 𝐺  ∘  𝐹 ) ‘ ( ◡ 𝐺 ‘ 𝑥 ) )  =  ( 𝐺 ‘ ( 𝐹 ‘ ( ◡ 𝐺 ‘ 𝑥 ) ) ) ) | 
						
							| 37 | 33 35 36 | syl2anc | ⊢ ( ( ( 𝐹 : 𝐴 ⟶ 𝐴  ∧  𝐺 : 𝐴 –1-1-onto→ 𝐴 )  ∧  𝑥  ∈  𝐴 )  →  ( ( 𝐺  ∘  𝐹 ) ‘ ( ◡ 𝐺 ‘ 𝑥 ) )  =  ( 𝐺 ‘ ( 𝐹 ‘ ( ◡ 𝐺 ‘ 𝑥 ) ) ) ) | 
						
							| 38 | 31 37 | eqtrd | ⊢ ( ( ( 𝐹 : 𝐴 ⟶ 𝐴  ∧  𝐺 : 𝐴 –1-1-onto→ 𝐴 )  ∧  𝑥  ∈  𝐴 )  →  ( ( ( 𝐺  ∘  𝐹 )  ∘  ◡ 𝐺 ) ‘ 𝑥 )  =  ( 𝐺 ‘ ( 𝐹 ‘ ( ◡ 𝐺 ‘ 𝑥 ) ) ) ) | 
						
							| 39 | 38 | eqeq1d | ⊢ ( ( ( 𝐹 : 𝐴 ⟶ 𝐴  ∧  𝐺 : 𝐴 –1-1-onto→ 𝐴 )  ∧  𝑥  ∈  𝐴 )  →  ( ( ( ( 𝐺  ∘  𝐹 )  ∘  ◡ 𝐺 ) ‘ 𝑥 )  =  𝑥  ↔  ( 𝐺 ‘ ( 𝐹 ‘ ( ◡ 𝐺 ‘ 𝑥 ) ) )  =  𝑥 ) ) | 
						
							| 40 |  | simplr | ⊢ ( ( ( 𝐹 : 𝐴 ⟶ 𝐴  ∧  𝐺 : 𝐴 –1-1-onto→ 𝐴 )  ∧  𝑥  ∈  𝐴 )  →  𝐺 : 𝐴 –1-1-onto→ 𝐴 ) | 
						
							| 41 |  | simpll | ⊢ ( ( ( 𝐹 : 𝐴 ⟶ 𝐴  ∧  𝐺 : 𝐴 –1-1-onto→ 𝐴 )  ∧  𝑥  ∈  𝐴 )  →  𝐹 : 𝐴 ⟶ 𝐴 ) | 
						
							| 42 |  | ffvelcdm | ⊢ ( ( 𝐹 : 𝐴 ⟶ 𝐴  ∧  ( ◡ 𝐺 ‘ 𝑥 )  ∈  𝐴 )  →  ( 𝐹 ‘ ( ◡ 𝐺 ‘ 𝑥 ) )  ∈  𝐴 ) | 
						
							| 43 | 41 35 42 | syl2anc | ⊢ ( ( ( 𝐹 : 𝐴 ⟶ 𝐴  ∧  𝐺 : 𝐴 –1-1-onto→ 𝐴 )  ∧  𝑥  ∈  𝐴 )  →  ( 𝐹 ‘ ( ◡ 𝐺 ‘ 𝑥 ) )  ∈  𝐴 ) | 
						
							| 44 |  | simpr | ⊢ ( ( ( 𝐹 : 𝐴 ⟶ 𝐴  ∧  𝐺 : 𝐴 –1-1-onto→ 𝐴 )  ∧  𝑥  ∈  𝐴 )  →  𝑥  ∈  𝐴 ) | 
						
							| 45 |  | f1ocnvfvb | ⊢ ( ( 𝐺 : 𝐴 –1-1-onto→ 𝐴  ∧  ( 𝐹 ‘ ( ◡ 𝐺 ‘ 𝑥 ) )  ∈  𝐴  ∧  𝑥  ∈  𝐴 )  →  ( ( 𝐺 ‘ ( 𝐹 ‘ ( ◡ 𝐺 ‘ 𝑥 ) ) )  =  𝑥  ↔  ( ◡ 𝐺 ‘ 𝑥 )  =  ( 𝐹 ‘ ( ◡ 𝐺 ‘ 𝑥 ) ) ) ) | 
						
							| 46 | 40 43 44 45 | syl3anc | ⊢ ( ( ( 𝐹 : 𝐴 ⟶ 𝐴  ∧  𝐺 : 𝐴 –1-1-onto→ 𝐴 )  ∧  𝑥  ∈  𝐴 )  →  ( ( 𝐺 ‘ ( 𝐹 ‘ ( ◡ 𝐺 ‘ 𝑥 ) ) )  =  𝑥  ↔  ( ◡ 𝐺 ‘ 𝑥 )  =  ( 𝐹 ‘ ( ◡ 𝐺 ‘ 𝑥 ) ) ) ) | 
						
							| 47 | 39 46 | bitrd | ⊢ ( ( ( 𝐹 : 𝐴 ⟶ 𝐴  ∧  𝐺 : 𝐴 –1-1-onto→ 𝐴 )  ∧  𝑥  ∈  𝐴 )  →  ( ( ( ( 𝐺  ∘  𝐹 )  ∘  ◡ 𝐺 ) ‘ 𝑥 )  =  𝑥  ↔  ( ◡ 𝐺 ‘ 𝑥 )  =  ( 𝐹 ‘ ( ◡ 𝐺 ‘ 𝑥 ) ) ) ) | 
						
							| 48 | 47 | necon3bid | ⊢ ( ( ( 𝐹 : 𝐴 ⟶ 𝐴  ∧  𝐺 : 𝐴 –1-1-onto→ 𝐴 )  ∧  𝑥  ∈  𝐴 )  →  ( ( ( ( 𝐺  ∘  𝐹 )  ∘  ◡ 𝐺 ) ‘ 𝑥 )  ≠  𝑥  ↔  ( ◡ 𝐺 ‘ 𝑥 )  ≠  ( 𝐹 ‘ ( ◡ 𝐺 ‘ 𝑥 ) ) ) ) | 
						
							| 49 |  | necom | ⊢ ( ( ◡ 𝐺 ‘ 𝑥 )  ≠  ( 𝐹 ‘ ( ◡ 𝐺 ‘ 𝑥 ) )  ↔  ( 𝐹 ‘ ( ◡ 𝐺 ‘ 𝑥 ) )  ≠  ( ◡ 𝐺 ‘ 𝑥 ) ) | 
						
							| 50 |  | f1of1 | ⊢ ( 𝐺 : 𝐴 –1-1-onto→ 𝐴  →  𝐺 : 𝐴 –1-1→ 𝐴 ) | 
						
							| 51 | 50 | ad2antlr | ⊢ ( ( ( 𝐹 : 𝐴 ⟶ 𝐴  ∧  𝐺 : 𝐴 –1-1-onto→ 𝐴 )  ∧  𝑥  ∈  𝐴 )  →  𝐺 : 𝐴 –1-1→ 𝐴 ) | 
						
							| 52 |  | difss | ⊢ ( 𝐹  ∖   I  )  ⊆  𝐹 | 
						
							| 53 |  | dmss | ⊢ ( ( 𝐹  ∖   I  )  ⊆  𝐹  →  dom  ( 𝐹  ∖   I  )  ⊆  dom  𝐹 ) | 
						
							| 54 | 52 53 | ax-mp | ⊢ dom  ( 𝐹  ∖   I  )  ⊆  dom  𝐹 | 
						
							| 55 |  | fdm | ⊢ ( 𝐹 : 𝐴 ⟶ 𝐴  →  dom  𝐹  =  𝐴 ) | 
						
							| 56 | 54 55 | sseqtrid | ⊢ ( 𝐹 : 𝐴 ⟶ 𝐴  →  dom  ( 𝐹  ∖   I  )  ⊆  𝐴 ) | 
						
							| 57 | 56 | ad2antrr | ⊢ ( ( ( 𝐹 : 𝐴 ⟶ 𝐴  ∧  𝐺 : 𝐴 –1-1-onto→ 𝐴 )  ∧  𝑥  ∈  𝐴 )  →  dom  ( 𝐹  ∖   I  )  ⊆  𝐴 ) | 
						
							| 58 |  | f1elima | ⊢ ( ( 𝐺 : 𝐴 –1-1→ 𝐴  ∧  ( ◡ 𝐺 ‘ 𝑥 )  ∈  𝐴  ∧  dom  ( 𝐹  ∖   I  )  ⊆  𝐴 )  →  ( ( 𝐺 ‘ ( ◡ 𝐺 ‘ 𝑥 ) )  ∈  ( 𝐺  “  dom  ( 𝐹  ∖   I  ) )  ↔  ( ◡ 𝐺 ‘ 𝑥 )  ∈  dom  ( 𝐹  ∖   I  ) ) ) | 
						
							| 59 | 51 35 57 58 | syl3anc | ⊢ ( ( ( 𝐹 : 𝐴 ⟶ 𝐴  ∧  𝐺 : 𝐴 –1-1-onto→ 𝐴 )  ∧  𝑥  ∈  𝐴 )  →  ( ( 𝐺 ‘ ( ◡ 𝐺 ‘ 𝑥 ) )  ∈  ( 𝐺  “  dom  ( 𝐹  ∖   I  ) )  ↔  ( ◡ 𝐺 ‘ 𝑥 )  ∈  dom  ( 𝐹  ∖   I  ) ) ) | 
						
							| 60 |  | f1ocnvfv2 | ⊢ ( ( 𝐺 : 𝐴 –1-1-onto→ 𝐴  ∧  𝑥  ∈  𝐴 )  →  ( 𝐺 ‘ ( ◡ 𝐺 ‘ 𝑥 ) )  =  𝑥 ) | 
						
							| 61 | 60 | adantll | ⊢ ( ( ( 𝐹 : 𝐴 ⟶ 𝐴  ∧  𝐺 : 𝐴 –1-1-onto→ 𝐴 )  ∧  𝑥  ∈  𝐴 )  →  ( 𝐺 ‘ ( ◡ 𝐺 ‘ 𝑥 ) )  =  𝑥 ) | 
						
							| 62 | 61 | eleq1d | ⊢ ( ( ( 𝐹 : 𝐴 ⟶ 𝐴  ∧  𝐺 : 𝐴 –1-1-onto→ 𝐴 )  ∧  𝑥  ∈  𝐴 )  →  ( ( 𝐺 ‘ ( ◡ 𝐺 ‘ 𝑥 ) )  ∈  ( 𝐺  “  dom  ( 𝐹  ∖   I  ) )  ↔  𝑥  ∈  ( 𝐺  “  dom  ( 𝐹  ∖   I  ) ) ) ) | 
						
							| 63 |  | fnelnfp | ⊢ ( ( 𝐹  Fn  𝐴  ∧  ( ◡ 𝐺 ‘ 𝑥 )  ∈  𝐴 )  →  ( ( ◡ 𝐺 ‘ 𝑥 )  ∈  dom  ( 𝐹  ∖   I  )  ↔  ( 𝐹 ‘ ( ◡ 𝐺 ‘ 𝑥 ) )  ≠  ( ◡ 𝐺 ‘ 𝑥 ) ) ) | 
						
							| 64 | 33 35 63 | syl2anc | ⊢ ( ( ( 𝐹 : 𝐴 ⟶ 𝐴  ∧  𝐺 : 𝐴 –1-1-onto→ 𝐴 )  ∧  𝑥  ∈  𝐴 )  →  ( ( ◡ 𝐺 ‘ 𝑥 )  ∈  dom  ( 𝐹  ∖   I  )  ↔  ( 𝐹 ‘ ( ◡ 𝐺 ‘ 𝑥 ) )  ≠  ( ◡ 𝐺 ‘ 𝑥 ) ) ) | 
						
							| 65 | 59 62 64 | 3bitr3rd | ⊢ ( ( ( 𝐹 : 𝐴 ⟶ 𝐴  ∧  𝐺 : 𝐴 –1-1-onto→ 𝐴 )  ∧  𝑥  ∈  𝐴 )  →  ( ( 𝐹 ‘ ( ◡ 𝐺 ‘ 𝑥 ) )  ≠  ( ◡ 𝐺 ‘ 𝑥 )  ↔  𝑥  ∈  ( 𝐺  “  dom  ( 𝐹  ∖   I  ) ) ) ) | 
						
							| 66 | 49 65 | bitrid | ⊢ ( ( ( 𝐹 : 𝐴 ⟶ 𝐴  ∧  𝐺 : 𝐴 –1-1-onto→ 𝐴 )  ∧  𝑥  ∈  𝐴 )  →  ( ( ◡ 𝐺 ‘ 𝑥 )  ≠  ( 𝐹 ‘ ( ◡ 𝐺 ‘ 𝑥 ) )  ↔  𝑥  ∈  ( 𝐺  “  dom  ( 𝐹  ∖   I  ) ) ) ) | 
						
							| 67 | 27 48 66 | 3bitrd | ⊢ ( ( ( 𝐹 : 𝐴 ⟶ 𝐴  ∧  𝐺 : 𝐴 –1-1-onto→ 𝐴 )  ∧  𝑥  ∈  𝐴 )  →  ( 𝑥  ∈  dom  ( ( ( 𝐺  ∘  𝐹 )  ∘  ◡ 𝐺 )  ∖   I  )  ↔  𝑥  ∈  ( 𝐺  “  dom  ( 𝐹  ∖   I  ) ) ) ) | 
						
							| 68 | 11 17 67 | eqrdav | ⊢ ( ( 𝐹 : 𝐴 ⟶ 𝐴  ∧  𝐺 : 𝐴 –1-1-onto→ 𝐴 )  →  dom  ( ( ( 𝐺  ∘  𝐹 )  ∘  ◡ 𝐺 )  ∖   I  )  =  ( 𝐺  “  dom  ( 𝐹  ∖   I  ) ) ) |