| Step | Hyp | Ref | Expression | 
						
							| 1 |  | fucval.q |  | 
						
							| 2 |  | fucval.b |  | 
						
							| 3 |  | fucval.n |  | 
						
							| 4 |  | fucval.a |  | 
						
							| 5 |  | fucval.o |  | 
						
							| 6 |  | fucval.c |  | 
						
							| 7 |  | fucval.d |  | 
						
							| 8 |  | fuccofval.x |  | 
						
							| 9 |  | eqidd |  | 
						
							| 10 | 1 2 3 4 5 6 7 9 | fucval |  | 
						
							| 11 | 10 | fveq2d |  | 
						
							| 12 | 2 | ovexi |  | 
						
							| 13 | 12 12 | xpex |  | 
						
							| 14 | 13 12 | mpoex |  | 
						
							| 15 |  | catstr |  | 
						
							| 16 |  | ccoid |  | 
						
							| 17 |  | snsstp3 |  | 
						
							| 18 | 15 16 17 | strfv |  | 
						
							| 19 | 14 18 | ax-mp |  | 
						
							| 20 | 11 8 19 | 3eqtr4g |  |