| Step | Hyp | Ref | Expression | 
						
							| 1 |  | estrchomfn.c |  |-  C = ( ExtStrCat ` U ) | 
						
							| 2 |  | estrchomfn.u |  |-  ( ph -> U e. V ) | 
						
							| 3 |  | estrchomfn.h |  |-  H = ( Hom ` C ) | 
						
							| 4 | 1 2 3 | estrchomfn |  |-  ( ph -> H Fn ( U X. U ) ) | 
						
							| 5 | 1 2 | estrcbas |  |-  ( ph -> U = ( Base ` C ) ) | 
						
							| 6 | 5 | eqcomd |  |-  ( ph -> ( Base ` C ) = U ) | 
						
							| 7 | 6 | sqxpeqd |  |-  ( ph -> ( ( Base ` C ) X. ( Base ` C ) ) = ( U X. U ) ) | 
						
							| 8 | 7 | fneq2d |  |-  ( ph -> ( H Fn ( ( Base ` C ) X. ( Base ` C ) ) <-> H Fn ( U X. U ) ) ) | 
						
							| 9 | 4 8 | mpbird |  |-  ( ph -> H Fn ( ( Base ` C ) X. ( Base ` C ) ) ) | 
						
							| 10 |  | eqid |  |-  ( Homf ` C ) = ( Homf ` C ) | 
						
							| 11 |  | eqid |  |-  ( Base ` C ) = ( Base ` C ) | 
						
							| 12 | 10 11 3 | fnhomeqhomf |  |-  ( H Fn ( ( Base ` C ) X. ( Base ` C ) ) -> ( Homf ` C ) = H ) | 
						
							| 13 | 9 12 | syl |  |-  ( ph -> ( Homf ` C ) = H ) |