| Step | Hyp | Ref | Expression | 
						
							| 1 |  | ioossioobi.a |  |-  ( ph -> A e. RR* ) | 
						
							| 2 |  | ioossioobi.b |  |-  ( ph -> B e. RR* ) | 
						
							| 3 |  | ioossioobi.c |  |-  ( ph -> C e. RR* ) | 
						
							| 4 |  | ioossioobi.d |  |-  ( ph -> D e. RR* ) | 
						
							| 5 |  | ioossioobi.cltd |  |-  ( ph -> C < D ) | 
						
							| 6 |  | simpr |  |-  ( ( ph /\ ( C (,) D ) C_ ( A (,) B ) ) -> ( C (,) D ) C_ ( A (,) B ) ) | 
						
							| 7 |  | df-ioo |  |-  (,) = ( x e. RR* , y e. RR* |-> { z e. RR* | ( x < z /\ z < y ) } ) | 
						
							| 8 | 7 | ixxssxr |  |-  ( A (,) B ) C_ RR* | 
						
							| 9 |  | infxrss |  |-  ( ( ( C (,) D ) C_ ( A (,) B ) /\ ( A (,) B ) C_ RR* ) -> inf ( ( A (,) B ) , RR* , < ) <_ inf ( ( C (,) D ) , RR* , < ) ) | 
						
							| 10 | 6 8 9 | sylancl |  |-  ( ( ph /\ ( C (,) D ) C_ ( A (,) B ) ) -> inf ( ( A (,) B ) , RR* , < ) <_ inf ( ( C (,) D ) , RR* , < ) ) | 
						
							| 11 | 1 | adantr |  |-  ( ( ph /\ ( C (,) D ) C_ ( A (,) B ) ) -> A e. RR* ) | 
						
							| 12 | 2 | adantr |  |-  ( ( ph /\ ( C (,) D ) C_ ( A (,) B ) ) -> B e. RR* ) | 
						
							| 13 |  | ioon0 |  |-  ( ( C e. RR* /\ D e. RR* ) -> ( ( C (,) D ) =/= (/) <-> C < D ) ) | 
						
							| 14 | 3 4 13 | syl2anc |  |-  ( ph -> ( ( C (,) D ) =/= (/) <-> C < D ) ) | 
						
							| 15 | 5 14 | mpbird |  |-  ( ph -> ( C (,) D ) =/= (/) ) | 
						
							| 16 | 15 | adantr |  |-  ( ( ph /\ ( C (,) D ) C_ ( A (,) B ) ) -> ( C (,) D ) =/= (/) ) | 
						
							| 17 |  | ssn0 |  |-  ( ( ( C (,) D ) C_ ( A (,) B ) /\ ( C (,) D ) =/= (/) ) -> ( A (,) B ) =/= (/) ) | 
						
							| 18 | 6 16 17 | syl2anc |  |-  ( ( ph /\ ( C (,) D ) C_ ( A (,) B ) ) -> ( A (,) B ) =/= (/) ) | 
						
							| 19 |  | idd |  |-  ( ( w e. RR* /\ B e. RR* ) -> ( w < B -> w < B ) ) | 
						
							| 20 |  | xrltle |  |-  ( ( w e. RR* /\ B e. RR* ) -> ( w < B -> w <_ B ) ) | 
						
							| 21 |  | idd |  |-  ( ( A e. RR* /\ w e. RR* ) -> ( A < w -> A < w ) ) | 
						
							| 22 |  | xrltle |  |-  ( ( A e. RR* /\ w e. RR* ) -> ( A < w -> A <_ w ) ) | 
						
							| 23 | 7 19 20 21 22 | ixxlb |  |-  ( ( A e. RR* /\ B e. RR* /\ ( A (,) B ) =/= (/) ) -> inf ( ( A (,) B ) , RR* , < ) = A ) | 
						
							| 24 | 11 12 18 23 | syl3anc |  |-  ( ( ph /\ ( C (,) D ) C_ ( A (,) B ) ) -> inf ( ( A (,) B ) , RR* , < ) = A ) | 
						
							| 25 | 3 | adantr |  |-  ( ( ph /\ ( C (,) D ) C_ ( A (,) B ) ) -> C e. RR* ) | 
						
							| 26 | 4 | adantr |  |-  ( ( ph /\ ( C (,) D ) C_ ( A (,) B ) ) -> D e. RR* ) | 
						
							| 27 |  | idd |  |-  ( ( w e. RR* /\ D e. RR* ) -> ( w < D -> w < D ) ) | 
						
							| 28 |  | xrltle |  |-  ( ( w e. RR* /\ D e. RR* ) -> ( w < D -> w <_ D ) ) | 
						
							| 29 |  | idd |  |-  ( ( C e. RR* /\ w e. RR* ) -> ( C < w -> C < w ) ) | 
						
							| 30 |  | xrltle |  |-  ( ( C e. RR* /\ w e. RR* ) -> ( C < w -> C <_ w ) ) | 
						
							| 31 | 7 27 28 29 30 | ixxlb |  |-  ( ( C e. RR* /\ D e. RR* /\ ( C (,) D ) =/= (/) ) -> inf ( ( C (,) D ) , RR* , < ) = C ) | 
						
							| 32 | 25 26 16 31 | syl3anc |  |-  ( ( ph /\ ( C (,) D ) C_ ( A (,) B ) ) -> inf ( ( C (,) D ) , RR* , < ) = C ) | 
						
							| 33 | 10 24 32 | 3brtr3d |  |-  ( ( ph /\ ( C (,) D ) C_ ( A (,) B ) ) -> A <_ C ) | 
						
							| 34 |  | supxrss |  |-  ( ( ( C (,) D ) C_ ( A (,) B ) /\ ( A (,) B ) C_ RR* ) -> sup ( ( C (,) D ) , RR* , < ) <_ sup ( ( A (,) B ) , RR* , < ) ) | 
						
							| 35 | 6 8 34 | sylancl |  |-  ( ( ph /\ ( C (,) D ) C_ ( A (,) B ) ) -> sup ( ( C (,) D ) , RR* , < ) <_ sup ( ( A (,) B ) , RR* , < ) ) | 
						
							| 36 | 7 27 28 29 30 | ixxub |  |-  ( ( C e. RR* /\ D e. RR* /\ ( C (,) D ) =/= (/) ) -> sup ( ( C (,) D ) , RR* , < ) = D ) | 
						
							| 37 | 25 26 16 36 | syl3anc |  |-  ( ( ph /\ ( C (,) D ) C_ ( A (,) B ) ) -> sup ( ( C (,) D ) , RR* , < ) = D ) | 
						
							| 38 | 7 19 20 21 22 | ixxub |  |-  ( ( A e. RR* /\ B e. RR* /\ ( A (,) B ) =/= (/) ) -> sup ( ( A (,) B ) , RR* , < ) = B ) | 
						
							| 39 | 11 12 18 38 | syl3anc |  |-  ( ( ph /\ ( C (,) D ) C_ ( A (,) B ) ) -> sup ( ( A (,) B ) , RR* , < ) = B ) | 
						
							| 40 | 35 37 39 | 3brtr3d |  |-  ( ( ph /\ ( C (,) D ) C_ ( A (,) B ) ) -> D <_ B ) | 
						
							| 41 | 33 40 | jca |  |-  ( ( ph /\ ( C (,) D ) C_ ( A (,) B ) ) -> ( A <_ C /\ D <_ B ) ) | 
						
							| 42 | 1 | adantr |  |-  ( ( ph /\ ( A <_ C /\ D <_ B ) ) -> A e. RR* ) | 
						
							| 43 | 2 | adantr |  |-  ( ( ph /\ ( A <_ C /\ D <_ B ) ) -> B e. RR* ) | 
						
							| 44 |  | simprl |  |-  ( ( ph /\ ( A <_ C /\ D <_ B ) ) -> A <_ C ) | 
						
							| 45 |  | simprr |  |-  ( ( ph /\ ( A <_ C /\ D <_ B ) ) -> D <_ B ) | 
						
							| 46 |  | ioossioo |  |-  ( ( ( A e. RR* /\ B e. RR* ) /\ ( A <_ C /\ D <_ B ) ) -> ( C (,) D ) C_ ( A (,) B ) ) | 
						
							| 47 | 42 43 44 45 46 | syl22anc |  |-  ( ( ph /\ ( A <_ C /\ D <_ B ) ) -> ( C (,) D ) C_ ( A (,) B ) ) | 
						
							| 48 | 41 47 | impbida |  |-  ( ph -> ( ( C (,) D ) C_ ( A (,) B ) <-> ( A <_ C /\ D <_ B ) ) ) |