| Step | Hyp | Ref | Expression | 
						
							| 1 |  | imasaddf.f |  | 
						
							| 2 |  | imasaddf.e |  | 
						
							| 3 |  | imasaddflem.a |  | 
						
							| 4 |  | df-ov |  | 
						
							| 5 | 1 2 3 | imasaddfnlem |  | 
						
							| 6 |  | fnfun |  | 
						
							| 7 | 5 6 | syl |  | 
						
							| 8 | 7 | 3ad2ant1 |  | 
						
							| 9 |  | fveq2 |  | 
						
							| 10 | 9 | opeq1d |  | 
						
							| 11 |  | fvoveq1 |  | 
						
							| 12 | 10 11 | opeq12d |  | 
						
							| 13 | 12 | sneqd |  | 
						
							| 14 | 13 | ssiun2s |  | 
						
							| 15 | 14 | 3ad2ant2 |  | 
						
							| 16 |  | fveq2 |  | 
						
							| 17 | 16 | opeq2d |  | 
						
							| 18 |  | oveq2 |  | 
						
							| 19 | 18 | fveq2d |  | 
						
							| 20 | 17 19 | opeq12d |  | 
						
							| 21 | 20 | sneqd |  | 
						
							| 22 | 21 | ssiun2s |  | 
						
							| 23 | 22 | ralrimivw |  | 
						
							| 24 |  | ss2iun |  | 
						
							| 25 | 23 24 | syl |  | 
						
							| 26 | 25 | 3ad2ant3 |  | 
						
							| 27 | 15 26 | sstrd |  | 
						
							| 28 | 3 | 3ad2ant1 |  | 
						
							| 29 | 27 28 | sseqtrrd |  | 
						
							| 30 |  | opex |  | 
						
							| 31 | 30 | snss |  | 
						
							| 32 | 29 31 | sylibr |  | 
						
							| 33 |  | funopfv |  | 
						
							| 34 | 8 32 33 | sylc |  | 
						
							| 35 | 4 34 | eqtrid |  |