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Description: All subspaces are subgroups. (Contributed by Stefan O'Rear, 11-Dec-2014)
| Ref | Expression | ||
|---|---|---|---|
| Hypothesis | lsssubg.s | |- S = ( LSubSp ` W ) |
|
| Assertion | lsssubg | |- ( ( W e. LMod /\ U e. S ) -> U e. ( SubGrp ` W ) ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | lsssubg.s | |- S = ( LSubSp ` W ) |
|
| 2 | eqid | |- ( Base ` W ) = ( Base ` W ) |
|
| 3 | 2 1 | lssss | |- ( U e. S -> U C_ ( Base ` W ) ) |
| 4 | 3 | adantl | |- ( ( W e. LMod /\ U e. S ) -> U C_ ( Base ` W ) ) |
| 5 | 1 | lssn0 | |- ( U e. S -> U =/= (/) ) |
| 6 | 5 | adantl | |- ( ( W e. LMod /\ U e. S ) -> U =/= (/) ) |
| 7 | eqid | |- ( +g ` W ) = ( +g ` W ) |
|
| 8 | 7 1 | lssvacl | |- ( ( ( W e. LMod /\ U e. S ) /\ ( x e. U /\ y e. U ) ) -> ( x ( +g ` W ) y ) e. U ) |
| 9 | 8 | anassrs | |- ( ( ( ( W e. LMod /\ U e. S ) /\ x e. U ) /\ y e. U ) -> ( x ( +g ` W ) y ) e. U ) |
| 10 | 9 | ralrimiva | |- ( ( ( W e. LMod /\ U e. S ) /\ x e. U ) -> A. y e. U ( x ( +g ` W ) y ) e. U ) |
| 11 | eqid | |- ( invg ` W ) = ( invg ` W ) |
|
| 12 | 1 11 | lssvnegcl | |- ( ( W e. LMod /\ U e. S /\ x e. U ) -> ( ( invg ` W ) ` x ) e. U ) |
| 13 | 12 | 3expa | |- ( ( ( W e. LMod /\ U e. S ) /\ x e. U ) -> ( ( invg ` W ) ` x ) e. U ) |
| 14 | 10 13 | jca | |- ( ( ( W e. LMod /\ U e. S ) /\ x e. U ) -> ( A. y e. U ( x ( +g ` W ) y ) e. U /\ ( ( invg ` W ) ` x ) e. U ) ) |
| 15 | 14 | ralrimiva | |- ( ( W e. LMod /\ U e. S ) -> A. x e. U ( A. y e. U ( x ( +g ` W ) y ) e. U /\ ( ( invg ` W ) ` x ) e. U ) ) |
| 16 | lmodgrp | |- ( W e. LMod -> W e. Grp ) |
|
| 17 | 16 | adantr | |- ( ( W e. LMod /\ U e. S ) -> W e. Grp ) |
| 18 | 2 7 11 | issubg2 | |- ( W e. Grp -> ( U e. ( SubGrp ` W ) <-> ( U C_ ( Base ` W ) /\ U =/= (/) /\ A. x e. U ( A. y e. U ( x ( +g ` W ) y ) e. U /\ ( ( invg ` W ) ` x ) e. U ) ) ) ) |
| 19 | 17 18 | syl | |- ( ( W e. LMod /\ U e. S ) -> ( U e. ( SubGrp ` W ) <-> ( U C_ ( Base ` W ) /\ U =/= (/) /\ A. x e. U ( A. y e. U ( x ( +g ` W ) y ) e. U /\ ( ( invg ` W ) ` x ) e. U ) ) ) ) |
| 20 | 4 6 15 19 | mpbir3and | |- ( ( W e. LMod /\ U e. S ) -> U e. ( SubGrp ` W ) ) |