| Step | Hyp | Ref | Expression | 
						
							| 1 |  | estrccat.c |  | 
						
							| 2 |  | id |  | 
						
							| 3 | 1 2 | estrcbas |  | 
						
							| 4 |  | eqidd |  | 
						
							| 5 |  | eqidd |  | 
						
							| 6 | 1 | fvexi |  | 
						
							| 7 | 6 | a1i |  | 
						
							| 8 |  | biid |  | 
						
							| 9 |  | f1oi |  | 
						
							| 10 |  | f1of |  | 
						
							| 11 | 9 10 | mp1i |  | 
						
							| 12 |  | simpl |  | 
						
							| 13 |  | eqid |  | 
						
							| 14 |  | simpr |  | 
						
							| 15 |  | eqid |  | 
						
							| 16 | 1 12 13 14 14 15 15 | elestrchom |  | 
						
							| 17 | 11 16 | mpbird |  | 
						
							| 18 |  | simpl |  | 
						
							| 19 |  | eqid |  | 
						
							| 20 |  | simpr1l |  | 
						
							| 21 |  | simpr1r |  | 
						
							| 22 |  | eqid |  | 
						
							| 23 |  | simpr31 |  | 
						
							| 24 | 1 18 13 20 21 22 15 | elestrchom |  | 
						
							| 25 | 23 24 | mpbid |  | 
						
							| 26 | 9 10 | mp1i |  | 
						
							| 27 | 1 18 19 20 21 21 22 15 15 25 26 | estrcco |  | 
						
							| 28 |  | fcoi2 |  | 
						
							| 29 | 25 28 | syl |  | 
						
							| 30 | 27 29 | eqtrd |  | 
						
							| 31 |  | simpr2l |  | 
						
							| 32 |  | eqid |  | 
						
							| 33 |  | simpr32 |  | 
						
							| 34 | 1 18 13 21 31 15 32 | elestrchom |  | 
						
							| 35 | 33 34 | mpbid |  | 
						
							| 36 | 1 18 19 21 21 31 15 15 32 26 35 | estrcco |  | 
						
							| 37 |  | fcoi1 |  | 
						
							| 38 | 35 37 | syl |  | 
						
							| 39 | 36 38 | eqtrd |  | 
						
							| 40 | 1 18 19 20 21 31 22 15 32 25 35 | estrcco |  | 
						
							| 41 |  | fco |  | 
						
							| 42 | 35 25 41 | syl2anc |  | 
						
							| 43 | 1 18 13 20 31 22 32 | elestrchom |  | 
						
							| 44 | 42 43 | mpbird |  | 
						
							| 45 | 40 44 | eqeltrd |  | 
						
							| 46 |  | coass |  | 
						
							| 47 |  | simpr2r |  | 
						
							| 48 |  | eqid |  | 
						
							| 49 |  | simpr33 |  | 
						
							| 50 | 1 18 13 31 47 32 48 | elestrchom |  | 
						
							| 51 | 49 50 | mpbid |  | 
						
							| 52 |  | fco |  | 
						
							| 53 | 51 35 52 | syl2anc |  | 
						
							| 54 | 1 18 19 20 21 47 22 15 48 25 53 | estrcco |  | 
						
							| 55 | 1 18 19 20 31 47 22 32 48 42 51 | estrcco |  | 
						
							| 56 | 46 54 55 | 3eqtr4a |  | 
						
							| 57 | 1 18 19 21 31 47 15 32 48 35 51 | estrcco |  | 
						
							| 58 | 57 | oveq1d |  | 
						
							| 59 | 40 | oveq2d |  | 
						
							| 60 | 56 58 59 | 3eqtr4d |  | 
						
							| 61 | 3 4 5 7 8 17 30 39 45 60 | iscatd2 |  |