| Step | Hyp | Ref | Expression | 
						
							| 1 |  | legval.p |  | 
						
							| 2 |  | legval.d |  | 
						
							| 3 |  | legval.i |  | 
						
							| 4 |  | legval.l |  | 
						
							| 5 |  | legval.g |  | 
						
							| 6 |  | elex |  | 
						
							| 7 |  | simp1 |  | 
						
							| 8 | 7 | eqcomd |  | 
						
							| 9 |  | simp2 |  | 
						
							| 10 | 9 | eqcomd |  | 
						
							| 11 | 10 | oveqd |  | 
						
							| 12 | 11 | eqeq2d |  | 
						
							| 13 |  | simp3 |  | 
						
							| 14 | 13 | eqcomd |  | 
						
							| 15 | 14 | oveqd |  | 
						
							| 16 | 15 | eleq2d |  | 
						
							| 17 | 10 | oveqd |  | 
						
							| 18 | 17 | eqeq2d |  | 
						
							| 19 | 16 18 | anbi12d |  | 
						
							| 20 | 8 19 | rexeqbidv |  | 
						
							| 21 | 12 20 | anbi12d |  | 
						
							| 22 | 8 21 | rexeqbidv |  | 
						
							| 23 | 8 22 | rexeqbidv |  | 
						
							| 24 | 1 2 3 23 | sbcie3s |  | 
						
							| 25 | 24 | opabbidv |  | 
						
							| 26 |  | df-leg |  | 
						
							| 27 | 2 | fvexi |  | 
						
							| 28 | 27 | imaex |  | 
						
							| 29 |  | p0ex |  | 
						
							| 30 | 28 29 | unex |  | 
						
							| 31 | 30 | a1i |  | 
						
							| 32 |  | simprr |  | 
						
							| 33 |  | ovima0 |  | 
						
							| 34 | 33 | ad5ant14 |  | 
						
							| 35 | 32 34 | eqeltrd |  | 
						
							| 36 |  | simpllr |  | 
						
							| 37 | 36 | simpld |  | 
						
							| 38 |  | ovima0 |  | 
						
							| 39 | 38 | ad3antrrr |  | 
						
							| 40 | 37 39 | eqeltrd |  | 
						
							| 41 | 35 40 | jca |  | 
						
							| 42 |  | simprr |  | 
						
							| 43 |  | eleq1w |  | 
						
							| 44 |  | oveq2 |  | 
						
							| 45 | 44 | eqeq2d |  | 
						
							| 46 | 43 45 | anbi12d |  | 
						
							| 47 | 46 | cbvrexvw |  | 
						
							| 48 | 42 47 | sylib |  | 
						
							| 49 | 41 48 | r19.29a |  | 
						
							| 50 | 49 | ex |  | 
						
							| 51 | 50 | rexlimivv |  | 
						
							| 52 | 51 | adantl |  | 
						
							| 53 | 52 | simpld |  | 
						
							| 54 | 52 | simprd |  | 
						
							| 55 | 31 31 53 54 | opabex2 |  | 
						
							| 56 | 55 | mptru |  | 
						
							| 57 | 25 26 56 | fvmpt |  | 
						
							| 58 | 5 6 57 | 3syl |  | 
						
							| 59 | 4 58 | eqtrid |  |