| Step | Hyp | Ref | Expression | 
						
							| 1 |  | wwlksnextprop.x |  | 
						
							| 2 |  | wwlksnextprop.e |  | 
						
							| 3 |  | wwlksnextprop.y |  | 
						
							| 4 |  | peano2nn0 |  | 
						
							| 5 |  | iswwlksn |  | 
						
							| 6 | 4 5 | syl |  | 
						
							| 7 |  | eqid |  | 
						
							| 8 | 7 | wwlkbp |  | 
						
							| 9 |  | lencl |  | 
						
							| 10 |  | eqcom |  | 
						
							| 11 |  | nn0cn |  | 
						
							| 12 | 11 | adantr |  | 
						
							| 13 |  | 1cnd |  | 
						
							| 14 |  | nn0cn |  | 
						
							| 15 | 4 14 | syl |  | 
						
							| 16 | 15 | adantl |  | 
						
							| 17 |  | subadd2 |  | 
						
							| 18 | 17 | bicomd |  | 
						
							| 19 | 12 13 16 18 | syl3anc |  | 
						
							| 20 | 10 19 | bitrid |  | 
						
							| 21 |  | eqcom |  | 
						
							| 22 | 21 | biimpi |  | 
						
							| 23 | 20 22 | biimtrdi |  | 
						
							| 24 | 23 | ex |  | 
						
							| 25 | 24 | com23 |  | 
						
							| 26 | 9 25 | syl |  | 
						
							| 27 | 8 26 | simpl2im |  | 
						
							| 28 | 27 | imp31 |  | 
						
							| 29 | 28 | oveq2d |  | 
						
							| 30 |  | simpll |  | 
						
							| 31 |  | nn0ge0 |  | 
						
							| 32 |  | 2re |  | 
						
							| 33 | 32 | a1i |  | 
						
							| 34 |  | nn0re |  | 
						
							| 35 | 33 34 | addge02d |  | 
						
							| 36 | 31 35 | mpbid |  | 
						
							| 37 |  | nn0cn |  | 
						
							| 38 |  | 1cnd |  | 
						
							| 39 | 37 38 38 | addassd |  | 
						
							| 40 |  | 1p1e2 |  | 
						
							| 41 | 40 | a1i |  | 
						
							| 42 | 41 | oveq2d |  | 
						
							| 43 | 39 42 | eqtrd |  | 
						
							| 44 | 36 43 | breqtrrd |  | 
						
							| 45 | 44 | adantl |  | 
						
							| 46 |  | breq2 |  | 
						
							| 47 | 46 | ad2antlr |  | 
						
							| 48 | 45 47 | mpbird |  | 
						
							| 49 |  | wwlksm1edg |  | 
						
							| 50 | 30 48 49 | syl2anc |  | 
						
							| 51 | 29 50 | eqeltrd |  | 
						
							| 52 | 51 | expcom |  | 
						
							| 53 | 6 52 | sylbid |  | 
						
							| 54 | 53 | com12 |  | 
						
							| 55 | 54 | adantr |  | 
						
							| 56 | 55 | imp |  | 
						
							| 57 | 7 2 | wwlknp |  | 
						
							| 58 |  | simpll |  | 
						
							| 59 |  | peano2nn0 |  | 
						
							| 60 | 4 59 | syl |  | 
						
							| 61 |  | peano2re |  | 
						
							| 62 | 34 61 | syl |  | 
						
							| 63 | 62 | lep1d |  | 
						
							| 64 |  | elfz2nn0 |  | 
						
							| 65 | 4 60 63 64 | syl3anbrc |  | 
						
							| 66 | 65 | adantl |  | 
						
							| 67 |  | oveq2 |  | 
						
							| 68 | 67 | adantr |  | 
						
							| 69 | 66 68 | eleqtrrd |  | 
						
							| 70 | 69 | adantll |  | 
						
							| 71 | 58 70 | jca |  | 
						
							| 72 | 71 | ex |  | 
						
							| 73 | 72 | 3adant3 |  | 
						
							| 74 | 57 73 | syl |  | 
						
							| 75 | 74 | adantr |  | 
						
							| 76 | 75 | imp |  | 
						
							| 77 |  | pfxlen |  | 
						
							| 78 | 76 77 | syl |  | 
						
							| 79 | 56 78 | jca |  | 
						
							| 80 |  | iswwlksn |  | 
						
							| 81 | 80 | adantl |  | 
						
							| 82 | 79 81 | mpbird |  | 
						
							| 83 | 82 | exp31 |  | 
						
							| 84 | 83 1 | eleq2s |  | 
						
							| 85 | 84 | 3imp |  | 
						
							| 86 | 1 | wwlksnextproplem1 |  | 
						
							| 87 | 86 | 3adant2 |  | 
						
							| 88 |  | simp2 |  | 
						
							| 89 | 87 88 | eqtrd |  | 
						
							| 90 |  | fveq1 |  | 
						
							| 91 | 90 | eqeq1d |  | 
						
							| 92 | 91 3 | elrab2 |  | 
						
							| 93 | 85 89 92 | sylanbrc |  |