| Step | Hyp | Ref | Expression | 
						
							| 1 |  | 2wlkd.p |  | 
						
							| 2 |  | 2wlkd.f |  | 
						
							| 3 |  | 2wlkd.s |  | 
						
							| 4 | 1 2 3 | 2wlkdlem3 |  | 
						
							| 5 |  | simp1 |  | 
						
							| 6 | 5 | eleq1d |  | 
						
							| 7 |  | simp2 |  | 
						
							| 8 | 7 | eleq1d |  | 
						
							| 9 |  | simp3 |  | 
						
							| 10 | 9 | eleq1d |  | 
						
							| 11 | 6 8 10 | 3anbi123d |  | 
						
							| 12 | 11 | bicomd |  | 
						
							| 13 | 4 12 | syl |  | 
						
							| 14 | 3 13 | mpbid |  | 
						
							| 15 | 2 | fveq2i |  | 
						
							| 16 |  | s2len |  | 
						
							| 17 | 15 16 | eqtri |  | 
						
							| 18 | 17 | oveq2i |  | 
						
							| 19 |  | fz0tp |  | 
						
							| 20 | 18 19 | eqtri |  | 
						
							| 21 | 20 | raleqi |  | 
						
							| 22 |  | c0ex |  | 
						
							| 23 |  | 1ex |  | 
						
							| 24 |  | 2ex |  | 
						
							| 25 |  | fveq2 |  | 
						
							| 26 | 25 | eleq1d |  | 
						
							| 27 |  | fveq2 |  | 
						
							| 28 | 27 | eleq1d |  | 
						
							| 29 |  | fveq2 |  | 
						
							| 30 | 29 | eleq1d |  | 
						
							| 31 | 22 23 24 26 28 30 | raltp |  | 
						
							| 32 | 21 31 | bitri |  | 
						
							| 33 | 14 32 | sylibr |  |