| Step | 
						Hyp | 
						Ref | 
						Expression | 
					
						
							| 1 | 
							
								
							 | 
							eqid | 
							⊢ ( 𝑥  ∈  ℂ ,  𝑦  ∈  ℂ  ↦  ( 𝑥  ·  𝑦 ) )  =  ( 𝑥  ∈  ℂ ,  𝑦  ∈  ℂ  ↦  ( 𝑥  ·  𝑦 ) )  | 
						
						
							| 2 | 
							
								
							 | 
							ovex | 
							⊢ ( 𝑥  ·  𝑦 )  ∈  V  | 
						
						
							| 3 | 
							
								1 2
							 | 
							fnmpoi | 
							⊢ ( 𝑥  ∈  ℂ ,  𝑦  ∈  ℂ  ↦  ( 𝑥  ·  𝑦 ) )  Fn  ( ℂ  ×  ℂ )  | 
						
						
							| 4 | 
							
								
							 | 
							simpll | 
							⊢ ( ( ( 𝑥  ∈  ℂ  ∧  𝑦  ∈  ℂ )  ∧  𝑧  =  ( 𝑥  ·  𝑦 ) )  →  𝑥  ∈  ℂ )  | 
						
						
							| 5 | 
							
								
							 | 
							simplr | 
							⊢ ( ( ( 𝑥  ∈  ℂ  ∧  𝑦  ∈  ℂ )  ∧  𝑧  =  ( 𝑥  ·  𝑦 ) )  →  𝑦  ∈  ℂ )  | 
						
						
							| 6 | 
							
								
							 | 
							mulcl | 
							⊢ ( ( 𝑥  ∈  ℂ  ∧  𝑦  ∈  ℂ )  →  ( 𝑥  ·  𝑦 )  ∈  ℂ )  | 
						
						
							| 7 | 
							
								
							 | 
							eleq1a | 
							⊢ ( ( 𝑥  ·  𝑦 )  ∈  ℂ  →  ( 𝑧  =  ( 𝑥  ·  𝑦 )  →  𝑧  ∈  ℂ ) )  | 
						
						
							| 8 | 
							
								6 7
							 | 
							syl | 
							⊢ ( ( 𝑥  ∈  ℂ  ∧  𝑦  ∈  ℂ )  →  ( 𝑧  =  ( 𝑥  ·  𝑦 )  →  𝑧  ∈  ℂ ) )  | 
						
						
							| 9 | 
							
								8
							 | 
							imp | 
							⊢ ( ( ( 𝑥  ∈  ℂ  ∧  𝑦  ∈  ℂ )  ∧  𝑧  =  ( 𝑥  ·  𝑦 ) )  →  𝑧  ∈  ℂ )  | 
						
						
							| 10 | 
							
								4 5 9
							 | 
							3jca | 
							⊢ ( ( ( 𝑥  ∈  ℂ  ∧  𝑦  ∈  ℂ )  ∧  𝑧  =  ( 𝑥  ·  𝑦 ) )  →  ( 𝑥  ∈  ℂ  ∧  𝑦  ∈  ℂ  ∧  𝑧  ∈  ℂ ) )  | 
						
						
							| 11 | 
							
								10
							 | 
							ssoprab2i | 
							⊢ { 〈 〈 𝑥 ,  𝑦 〉 ,  𝑧 〉  ∣  ( ( 𝑥  ∈  ℂ  ∧  𝑦  ∈  ℂ )  ∧  𝑧  =  ( 𝑥  ·  𝑦 ) ) }  ⊆  { 〈 〈 𝑥 ,  𝑦 〉 ,  𝑧 〉  ∣  ( 𝑥  ∈  ℂ  ∧  𝑦  ∈  ℂ  ∧  𝑧  ∈  ℂ ) }  | 
						
						
							| 12 | 
							
								
							 | 
							df-mpo | 
							⊢ ( 𝑥  ∈  ℂ ,  𝑦  ∈  ℂ  ↦  ( 𝑥  ·  𝑦 ) )  =  { 〈 〈 𝑥 ,  𝑦 〉 ,  𝑧 〉  ∣  ( ( 𝑥  ∈  ℂ  ∧  𝑦  ∈  ℂ )  ∧  𝑧  =  ( 𝑥  ·  𝑦 ) ) }  | 
						
						
							| 13 | 
							
								
							 | 
							dfxp3 | 
							⊢ ( ( ℂ  ×  ℂ )  ×  ℂ )  =  { 〈 〈 𝑥 ,  𝑦 〉 ,  𝑧 〉  ∣  ( 𝑥  ∈  ℂ  ∧  𝑦  ∈  ℂ  ∧  𝑧  ∈  ℂ ) }  | 
						
						
							| 14 | 
							
								11 12 13
							 | 
							3sstr4i | 
							⊢ ( 𝑥  ∈  ℂ ,  𝑦  ∈  ℂ  ↦  ( 𝑥  ·  𝑦 ) )  ⊆  ( ( ℂ  ×  ℂ )  ×  ℂ )  | 
						
						
							| 15 | 
							
								
							 | 
							dff2 | 
							⊢ ( ( 𝑥  ∈  ℂ ,  𝑦  ∈  ℂ  ↦  ( 𝑥  ·  𝑦 ) ) : ( ℂ  ×  ℂ ) ⟶ ℂ  ↔  ( ( 𝑥  ∈  ℂ ,  𝑦  ∈  ℂ  ↦  ( 𝑥  ·  𝑦 ) )  Fn  ( ℂ  ×  ℂ )  ∧  ( 𝑥  ∈  ℂ ,  𝑦  ∈  ℂ  ↦  ( 𝑥  ·  𝑦 ) )  ⊆  ( ( ℂ  ×  ℂ )  ×  ℂ ) ) )  | 
						
						
							| 16 | 
							
								3 14 15
							 | 
							mpbir2an | 
							⊢ ( 𝑥  ∈  ℂ ,  𝑦  ∈  ℂ  ↦  ( 𝑥  ·  𝑦 ) ) : ( ℂ  ×  ℂ ) ⟶ ℂ  |