Theorem lplnric

Description: Property of a lattice plane expressed as the join of 3 atoms. (Contributed by NM, 30-Jul-2012)

	Ref	Expression
Hypotheses	islpln2a.l	|- .<_ = ( le ` K )
	islpln2a.j	|- .\/ = ( join ` K )
	islpln2a.a	|- A = ( Atoms ` K )
	islpln2a.p	|- P = ( LPlanes ` K )
	islpln2a.y	|- Y = ( ( Q .\/ R ) .\/ S )
Assertion	lplnric	|- ( ( K e. HL /\ ( Q e. A /\ R e. A /\ S e. A ) /\ Y e. P ) -> -. S .<_ ( Q .\/ R ) )

Proof

Step	Hyp	Ref	Expression
1		islpln2a.l	|- .<_ = ( le ` K )
2		islpln2a.j	|- .\/ = ( join ` K )
3		islpln2a.a	|- A = ( Atoms ` K )
4		islpln2a.p	|- P = ( LPlanes ` K )
5		islpln2a.y	|- Y = ( ( Q .\/ R ) .\/ S )
6	1 2 3 4 5	islpln2ah	|- ( ( K e. HL /\ ( Q e. A /\ R e. A /\ S e. A ) ) -> ( Y e. P <-> ( Q =/= R /\ -. S .<_ ( Q .\/ R ) ) ) )
7	6	biimp3a	|- ( ( K e. HL /\ ( Q e. A /\ R e. A /\ S e. A ) /\ Y e. P ) -> ( Q =/= R /\ -. S .<_ ( Q .\/ R ) ) )
8	7	simprd	|- ( ( K e. HL /\ ( Q e. A /\ R e. A /\ S e. A ) /\ Y e. P ) -> -. S .<_ ( Q .\/ R ) )