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Metamath Proof Explorer

Theorem lvoli

Description: Condition implying a 3-dim lattice volume. (Contributed by NM, 1-Jul-2012)

Ref Expression
Hypotheses lvolset.b 
|- B = ( Base ` K )
lvolset.c 
|- C = (
lvolset.p 
|- P = ( LPlanes ` K )
lvolset.v 
|- V = ( LVols ` K )
Assertion lvoli 
|- ( ( ( K e. D /\ Y e. B /\ X e. P ) /\ X C Y ) -> Y e. V )

Proof

Step Hyp Ref Expression
1 lvolset.b 
 |-  B = ( Base ` K )
2 lvolset.c 
 |-  C = (
3 lvolset.p 
 |-  P = ( LPlanes ` K )
4 lvolset.v 
 |-  V = ( LVols ` K )
5 simpl2 
 |-  ( ( ( K e. D /\ Y e. B /\ X e. P ) /\ X C Y ) -> Y e. B )
6 breq1 
 |-  ( x = X -> ( x C Y <-> X C Y ) )
7 6 rspcev 
 |-  ( ( X e. P /\ X C Y ) -> E. x e. P x C Y )
8 7 3ad2antl3 
 |-  ( ( ( K e. D /\ Y e. B /\ X e. P ) /\ X C Y ) -> E. x e. P x C Y )
9 simpl1 
 |-  ( ( ( K e. D /\ Y e. B /\ X e. P ) /\ X C Y ) -> K e. D )
10 1 2 3 4 islvol 
 |-  ( K e. D -> ( Y e. V <-> ( Y e. B /\ E. x e. P x C Y ) ) )
11 9 10 syl 
 |-  ( ( ( K e. D /\ Y e. B /\ X e. P ) /\ X C Y ) -> ( Y e. V <-> ( Y e. B /\ E. x e. P x C Y ) ) )
12 5 8 11 mpbir2and 
 |-  ( ( ( K e. D /\ Y e. B /\ X e. P ) /\ X C Y ) -> Y e. V )