| Step | Hyp | Ref | Expression | 
						
							| 1 |  | 3wlkd.p |  | 
						
							| 2 |  | 3wlkd.f |  | 
						
							| 3 |  | 3wlkd.s |  | 
						
							| 4 | 1 2 3 | 3wlkdlem3 |  | 
						
							| 5 |  | simpl |  | 
						
							| 6 | 5 | eleq1d |  | 
						
							| 7 |  | simpr |  | 
						
							| 8 | 7 | eleq1d |  | 
						
							| 9 | 6 8 | anbi12d |  | 
						
							| 10 | 9 | biimparc |  | 
						
							| 11 |  | c0ex |  | 
						
							| 12 |  | 1ex |  | 
						
							| 13 | 11 12 | pm3.2i |  | 
						
							| 14 |  | fveq2 |  | 
						
							| 15 | 14 | eleq1d |  | 
						
							| 16 |  | fveq2 |  | 
						
							| 17 | 16 | eleq1d |  | 
						
							| 18 | 15 17 | ralprg |  | 
						
							| 19 | 13 18 | mp1i |  | 
						
							| 20 | 10 19 | mpbird |  | 
						
							| 21 | 20 | ex |  | 
						
							| 22 |  | simpl |  | 
						
							| 23 | 22 | eleq1d |  | 
						
							| 24 |  | simpr |  | 
						
							| 25 | 24 | eleq1d |  | 
						
							| 26 | 23 25 | anbi12d |  | 
						
							| 27 | 26 | biimparc |  | 
						
							| 28 |  | 2ex |  | 
						
							| 29 |  | 3ex |  | 
						
							| 30 | 28 29 | pm3.2i |  | 
						
							| 31 |  | fveq2 |  | 
						
							| 32 | 31 | eleq1d |  | 
						
							| 33 |  | fveq2 |  | 
						
							| 34 | 33 | eleq1d |  | 
						
							| 35 | 32 34 | ralprg |  | 
						
							| 36 | 30 35 | mp1i |  | 
						
							| 37 | 27 36 | mpbird |  | 
						
							| 38 | 37 | ex |  | 
						
							| 39 | 21 38 | im2anan9 |  | 
						
							| 40 | 3 4 39 | sylc |  | 
						
							| 41 | 2 | fveq2i |  | 
						
							| 42 |  | s3len |  | 
						
							| 43 | 41 42 | eqtri |  | 
						
							| 44 | 43 | oveq2i |  | 
						
							| 45 |  | fz0to3un2pr |  | 
						
							| 46 | 44 45 | eqtri |  | 
						
							| 47 | 46 | raleqi |  | 
						
							| 48 |  | ralunb |  | 
						
							| 49 | 47 48 | bitri |  | 
						
							| 50 | 40 49 | sylibr |  |