| Step | Hyp | Ref | Expression | 
						
							| 1 |  | cntzfval.b |  | 
						
							| 2 |  | cntzfval.p |  | 
						
							| 3 |  | cntzfval.z |  | 
						
							| 4 |  | elex |  | 
						
							| 5 |  | fveq2 |  | 
						
							| 6 | 5 1 | eqtr4di |  | 
						
							| 7 | 6 | pweqd |  | 
						
							| 8 |  | fveq2 |  | 
						
							| 9 | 8 2 | eqtr4di |  | 
						
							| 10 | 9 | oveqd |  | 
						
							| 11 | 9 | oveqd |  | 
						
							| 12 | 10 11 | eqeq12d |  | 
						
							| 13 | 12 | ralbidv |  | 
						
							| 14 | 6 13 | rabeqbidv |  | 
						
							| 15 | 7 14 | mpteq12dv |  | 
						
							| 16 |  | df-cntz |  | 
						
							| 17 | 1 | fvexi |  | 
						
							| 18 | 17 | pwex |  | 
						
							| 19 | 18 | mptex |  | 
						
							| 20 | 15 16 19 | fvmpt |  | 
						
							| 21 | 4 20 | syl |  | 
						
							| 22 | 3 21 | eqtrid |  |