| Step | Hyp | Ref | Expression | 
						
							| 1 |  | sadval.a |  | 
						
							| 2 |  | sadval.b |  | 
						
							| 3 |  | sadval.c |  | 
						
							| 4 |  | sadcp1.n |  | 
						
							| 5 |  | nn0uz |  | 
						
							| 6 | 4 5 | eleqtrdi |  | 
						
							| 7 |  | seqp1 |  | 
						
							| 8 | 6 7 | syl |  | 
						
							| 9 | 3 | fveq1i |  | 
						
							| 10 | 3 | fveq1i |  | 
						
							| 11 | 10 | oveq1i |  | 
						
							| 12 | 8 9 11 | 3eqtr4g |  | 
						
							| 13 |  | peano2nn0 |  | 
						
							| 14 |  | eqeq1 |  | 
						
							| 15 |  | oveq1 |  | 
						
							| 16 | 14 15 | ifbieq2d |  | 
						
							| 17 |  | eqid |  | 
						
							| 18 |  | 0ex |  | 
						
							| 19 |  | ovex |  | 
						
							| 20 | 18 19 | ifex |  | 
						
							| 21 | 16 17 20 | fvmpt |  | 
						
							| 22 | 4 13 21 | 3syl |  | 
						
							| 23 |  | nn0p1nn |  | 
						
							| 24 | 4 23 | syl |  | 
						
							| 25 | 24 | nnne0d |  | 
						
							| 26 |  | ifnefalse |  | 
						
							| 27 | 25 26 | syl |  | 
						
							| 28 | 4 | nn0cnd |  | 
						
							| 29 |  | 1cnd |  | 
						
							| 30 | 28 29 | pncand |  | 
						
							| 31 | 22 27 30 | 3eqtrd |  | 
						
							| 32 | 31 | oveq2d |  | 
						
							| 33 | 1 2 3 | sadcf |  | 
						
							| 34 | 33 4 | ffvelcdmd |  | 
						
							| 35 |  | simpr |  | 
						
							| 36 | 35 | eleq1d |  | 
						
							| 37 | 35 | eleq1d |  | 
						
							| 38 |  | simpl |  | 
						
							| 39 | 38 | eleq2d |  | 
						
							| 40 | 36 37 39 | cadbi123d |  | 
						
							| 41 | 40 | ifbid |  | 
						
							| 42 |  | biidd |  | 
						
							| 43 |  | biidd |  | 
						
							| 44 |  | eleq2w |  | 
						
							| 45 | 42 43 44 | cadbi123d |  | 
						
							| 46 | 45 | ifbid |  | 
						
							| 47 |  | eleq1w |  | 
						
							| 48 |  | eleq1w |  | 
						
							| 49 |  | biidd |  | 
						
							| 50 | 47 48 49 | cadbi123d |  | 
						
							| 51 | 50 | ifbid |  | 
						
							| 52 | 46 51 | cbvmpov |  | 
						
							| 53 |  | 1oex |  | 
						
							| 54 | 53 18 | ifex |  | 
						
							| 55 | 41 52 54 | ovmpoa |  | 
						
							| 56 | 34 4 55 | syl2anc |  | 
						
							| 57 | 12 32 56 | 3eqtrd |  | 
						
							| 58 | 57 | eleq2d |  | 
						
							| 59 |  | noel |  | 
						
							| 60 |  | iffalse |  | 
						
							| 61 | 60 | eleq2d |  | 
						
							| 62 | 59 61 | mtbiri |  | 
						
							| 63 | 62 | con4i |  | 
						
							| 64 |  | 0lt1o |  | 
						
							| 65 |  | iftrue |  | 
						
							| 66 | 64 65 | eleqtrrid |  | 
						
							| 67 | 63 66 | impbii |  | 
						
							| 68 | 58 67 | bitrdi |  |