| Step | Hyp | Ref | Expression | 
						
							| 1 |  | ftc1.g |  |-  G = ( x e. ( A [,] B ) |-> S. ( A (,) x ) ( F ` t ) _d t ) | 
						
							| 2 |  | ftc1.a |  |-  ( ph -> A e. RR ) | 
						
							| 3 |  | ftc1.b |  |-  ( ph -> B e. RR ) | 
						
							| 4 |  | ftc1.le |  |-  ( ph -> A <_ B ) | 
						
							| 5 |  | ftc1.s |  |-  ( ph -> ( A (,) B ) C_ D ) | 
						
							| 6 |  | ftc1.d |  |-  ( ph -> D C_ RR ) | 
						
							| 7 |  | ftc1.i |  |-  ( ph -> F e. L^1 ) | 
						
							| 8 |  | ftc1a.f |  |-  ( ph -> F : D --> CC ) | 
						
							| 9 |  | fvexd |  |-  ( ( ( ph /\ x e. ( A [,] B ) ) /\ t e. ( A (,) x ) ) -> ( F ` t ) e. _V ) | 
						
							| 10 | 3 | adantr |  |-  ( ( ph /\ x e. ( A [,] B ) ) -> B e. RR ) | 
						
							| 11 | 10 | rexrd |  |-  ( ( ph /\ x e. ( A [,] B ) ) -> B e. RR* ) | 
						
							| 12 |  | elicc2 |  |-  ( ( A e. RR /\ B e. RR ) -> ( x e. ( A [,] B ) <-> ( x e. RR /\ A <_ x /\ x <_ B ) ) ) | 
						
							| 13 | 2 3 12 | syl2anc |  |-  ( ph -> ( x e. ( A [,] B ) <-> ( x e. RR /\ A <_ x /\ x <_ B ) ) ) | 
						
							| 14 | 13 | biimpa |  |-  ( ( ph /\ x e. ( A [,] B ) ) -> ( x e. RR /\ A <_ x /\ x <_ B ) ) | 
						
							| 15 | 14 | simp3d |  |-  ( ( ph /\ x e. ( A [,] B ) ) -> x <_ B ) | 
						
							| 16 |  | iooss2 |  |-  ( ( B e. RR* /\ x <_ B ) -> ( A (,) x ) C_ ( A (,) B ) ) | 
						
							| 17 | 11 15 16 | syl2anc |  |-  ( ( ph /\ x e. ( A [,] B ) ) -> ( A (,) x ) C_ ( A (,) B ) ) | 
						
							| 18 | 5 | adantr |  |-  ( ( ph /\ x e. ( A [,] B ) ) -> ( A (,) B ) C_ D ) | 
						
							| 19 | 17 18 | sstrd |  |-  ( ( ph /\ x e. ( A [,] B ) ) -> ( A (,) x ) C_ D ) | 
						
							| 20 |  | ioombl |  |-  ( A (,) x ) e. dom vol | 
						
							| 21 | 20 | a1i |  |-  ( ( ph /\ x e. ( A [,] B ) ) -> ( A (,) x ) e. dom vol ) | 
						
							| 22 |  | fvexd |  |-  ( ( ( ph /\ x e. ( A [,] B ) ) /\ t e. D ) -> ( F ` t ) e. _V ) | 
						
							| 23 | 8 | feqmptd |  |-  ( ph -> F = ( t e. D |-> ( F ` t ) ) ) | 
						
							| 24 | 23 7 | eqeltrrd |  |-  ( ph -> ( t e. D |-> ( F ` t ) ) e. L^1 ) | 
						
							| 25 | 24 | adantr |  |-  ( ( ph /\ x e. ( A [,] B ) ) -> ( t e. D |-> ( F ` t ) ) e. L^1 ) | 
						
							| 26 | 19 21 22 25 | iblss |  |-  ( ( ph /\ x e. ( A [,] B ) ) -> ( t e. ( A (,) x ) |-> ( F ` t ) ) e. L^1 ) | 
						
							| 27 | 9 26 | itgcl |  |-  ( ( ph /\ x e. ( A [,] B ) ) -> S. ( A (,) x ) ( F ` t ) _d t e. CC ) | 
						
							| 28 | 27 1 | fmptd |  |-  ( ph -> G : ( A [,] B ) --> CC ) |