| Step | 
						Hyp | 
						Ref | 
						Expression | 
					
						
							| 1 | 
							
								
							 | 
							ovolss.1 | 
							 |-  M = { y e. RR* | E. f e. ( ( <_ i^i ( RR X. RR ) ) ^m NN ) ( A C_ U. ran ( (,) o. f ) /\ y = sup ( ran seq 1 ( + , ( ( abs o. - ) o. f ) ) , RR* , < ) ) } | 
						
						
							| 2 | 
							
								
							 | 
							ovolss.2 | 
							 |-  N = { y e. RR* | E. f e. ( ( <_ i^i ( RR X. RR ) ) ^m NN ) ( B C_ U. ran ( (,) o. f ) /\ y = sup ( ran seq 1 ( + , ( ( abs o. - ) o. f ) ) , RR* , < ) ) } | 
						
						
							| 3 | 
							
								
							 | 
							sstr2 | 
							 |-  ( A C_ B -> ( B C_ U. ran ( (,) o. f ) -> A C_ U. ran ( (,) o. f ) ) )  | 
						
						
							| 4 | 
							
								3
							 | 
							ad2antrr | 
							 |-  ( ( ( A C_ B /\ B C_ RR ) /\ y e. RR* ) -> ( B C_ U. ran ( (,) o. f ) -> A C_ U. ran ( (,) o. f ) ) )  | 
						
						
							| 5 | 
							
								4
							 | 
							anim1d | 
							 |-  ( ( ( A C_ B /\ B C_ RR ) /\ y e. RR* ) -> ( ( B C_ U. ran ( (,) o. f ) /\ y = sup ( ran seq 1 ( + , ( ( abs o. - ) o. f ) ) , RR* , < ) ) -> ( A C_ U. ran ( (,) o. f ) /\ y = sup ( ran seq 1 ( + , ( ( abs o. - ) o. f ) ) , RR* , < ) ) ) )  | 
						
						
							| 6 | 
							
								5
							 | 
							reximdv | 
							 |-  ( ( ( A C_ B /\ B C_ RR ) /\ y e. RR* ) -> ( E. f e. ( ( <_ i^i ( RR X. RR ) ) ^m NN ) ( B C_ U. ran ( (,) o. f ) /\ y = sup ( ran seq 1 ( + , ( ( abs o. - ) o. f ) ) , RR* , < ) ) -> E. f e. ( ( <_ i^i ( RR X. RR ) ) ^m NN ) ( A C_ U. ran ( (,) o. f ) /\ y = sup ( ran seq 1 ( + , ( ( abs o. - ) o. f ) ) , RR* , < ) ) ) )  | 
						
						
							| 7 | 
							
								6
							 | 
							ss2rabdv | 
							 |-  ( ( A C_ B /\ B C_ RR ) -> { y e. RR* | E. f e. ( ( <_ i^i ( RR X. RR ) ) ^m NN ) ( B C_ U. ran ( (,) o. f ) /\ y = sup ( ran seq 1 ( + , ( ( abs o. - ) o. f ) ) , RR* , < ) ) } C_ { y e. RR* | E. f e. ( ( <_ i^i ( RR X. RR ) ) ^m NN ) ( A C_ U. ran ( (,) o. f ) /\ y = sup ( ran seq 1 ( + , ( ( abs o. - ) o. f ) ) , RR* , < ) ) } ) | 
						
						
							| 8 | 
							
								7 2 1
							 | 
							3sstr4g | 
							 |-  ( ( A C_ B /\ B C_ RR ) -> N C_ M )  | 
						
						
							| 9 | 
							
								
							 | 
							sstr | 
							 |-  ( ( A C_ B /\ B C_ RR ) -> A C_ RR )  | 
						
						
							| 10 | 
							
								1
							 | 
							ovolval | 
							 |-  ( A C_ RR -> ( vol* ` A ) = inf ( M , RR* , < ) )  | 
						
						
							| 11 | 
							
								10
							 | 
							adantr | 
							 |-  ( ( A C_ RR /\ x e. M ) -> ( vol* ` A ) = inf ( M , RR* , < ) )  | 
						
						
							| 12 | 
							
								1
							 | 
							ssrab3 | 
							 |-  M C_ RR*  | 
						
						
							| 13 | 
							
								
							 | 
							infxrlb | 
							 |-  ( ( M C_ RR* /\ x e. M ) -> inf ( M , RR* , < ) <_ x )  | 
						
						
							| 14 | 
							
								12 13
							 | 
							mpan | 
							 |-  ( x e. M -> inf ( M , RR* , < ) <_ x )  | 
						
						
							| 15 | 
							
								14
							 | 
							adantl | 
							 |-  ( ( A C_ RR /\ x e. M ) -> inf ( M , RR* , < ) <_ x )  | 
						
						
							| 16 | 
							
								11 15
							 | 
							eqbrtrd | 
							 |-  ( ( A C_ RR /\ x e. M ) -> ( vol* ` A ) <_ x )  | 
						
						
							| 17 | 
							
								16
							 | 
							ralrimiva | 
							 |-  ( A C_ RR -> A. x e. M ( vol* ` A ) <_ x )  | 
						
						
							| 18 | 
							
								9 17
							 | 
							syl | 
							 |-  ( ( A C_ B /\ B C_ RR ) -> A. x e. M ( vol* ` A ) <_ x )  | 
						
						
							| 19 | 
							
								
							 | 
							ssralv | 
							 |-  ( N C_ M -> ( A. x e. M ( vol* ` A ) <_ x -> A. x e. N ( vol* ` A ) <_ x ) )  | 
						
						
							| 20 | 
							
								8 18 19
							 | 
							sylc | 
							 |-  ( ( A C_ B /\ B C_ RR ) -> A. x e. N ( vol* ` A ) <_ x )  | 
						
						
							| 21 | 
							
								2
							 | 
							ssrab3 | 
							 |-  N C_ RR*  | 
						
						
							| 22 | 
							
								
							 | 
							ovolcl | 
							 |-  ( A C_ RR -> ( vol* ` A ) e. RR* )  | 
						
						
							| 23 | 
							
								9 22
							 | 
							syl | 
							 |-  ( ( A C_ B /\ B C_ RR ) -> ( vol* ` A ) e. RR* )  | 
						
						
							| 24 | 
							
								
							 | 
							infxrgelb | 
							 |-  ( ( N C_ RR* /\ ( vol* ` A ) e. RR* ) -> ( ( vol* ` A ) <_ inf ( N , RR* , < ) <-> A. x e. N ( vol* ` A ) <_ x ) )  | 
						
						
							| 25 | 
							
								21 23 24
							 | 
							sylancr | 
							 |-  ( ( A C_ B /\ B C_ RR ) -> ( ( vol* ` A ) <_ inf ( N , RR* , < ) <-> A. x e. N ( vol* ` A ) <_ x ) )  | 
						
						
							| 26 | 
							
								20 25
							 | 
							mpbird | 
							 |-  ( ( A C_ B /\ B C_ RR ) -> ( vol* ` A ) <_ inf ( N , RR* , < ) )  | 
						
						
							| 27 | 
							
								2
							 | 
							ovolval | 
							 |-  ( B C_ RR -> ( vol* ` B ) = inf ( N , RR* , < ) )  | 
						
						
							| 28 | 
							
								27
							 | 
							adantl | 
							 |-  ( ( A C_ B /\ B C_ RR ) -> ( vol* ` B ) = inf ( N , RR* , < ) )  | 
						
						
							| 29 | 
							
								26 28
							 | 
							breqtrrd | 
							 |-  ( ( A C_ B /\ B C_ RR ) -> ( vol* ` A ) <_ ( vol* ` B ) )  |