Theorem 4atlem4c

Description: Lemma for 4at . Frequently used associative law. (Contributed by NM, 9-Jul-2012)

	Ref	Expression
Hypotheses	4at.l	⊢ ≤ = ( le ‘ 𝐾 )
	4at.j	⊢ ∨ = ( join ‘ 𝐾 )
	4at.a	⊢ 𝐴 = ( Atoms ‘ 𝐾 )
Assertion	4atlem4c	⊢ ( ( ( 𝐾 ∈ HL ∧ 𝑃 ∈ 𝐴 ∧ 𝑄 ∈ 𝐴 ) ∧ ( 𝑅 ∈ 𝐴 ∧ 𝑆 ∈ 𝐴 ) ) → ( ( 𝑃 ∨ 𝑄 ) ∨ ( 𝑅 ∨ 𝑆 ) ) = ( 𝑅 ∨ ( ( 𝑃 ∨ 𝑄 ) ∨ 𝑆 ) ) )

Proof

Step	Hyp	Ref	Expression
1		4at.l	⊢ ≤ = ( le ‘ 𝐾 )
2		4at.j	⊢ ∨ = ( join ‘ 𝐾 )
3		4at.a	⊢ 𝐴 = ( Atoms ‘ 𝐾 )
4		simpl1	⊢ ( ( ( 𝐾 ∈ HL ∧ 𝑃 ∈ 𝐴 ∧ 𝑄 ∈ 𝐴 ) ∧ ( 𝑅 ∈ 𝐴 ∧ 𝑆 ∈ 𝐴 ) ) → 𝐾 ∈ HL )
5	4	hllatd	⊢ ( ( ( 𝐾 ∈ HL ∧ 𝑃 ∈ 𝐴 ∧ 𝑄 ∈ 𝐴 ) ∧ ( 𝑅 ∈ 𝐴 ∧ 𝑆 ∈ 𝐴 ) ) → 𝐾 ∈ Lat )
6		eqid	⊢ ( Base ‘ 𝐾 ) = ( Base ‘ 𝐾 )
7	6 2 3	hlatjcl	⊢ ( ( 𝐾 ∈ HL ∧ 𝑃 ∈ 𝐴 ∧ 𝑄 ∈ 𝐴 ) → ( 𝑃 ∨ 𝑄 ) ∈ ( Base ‘ 𝐾 ) )
8	7	adantr	⊢ ( ( ( 𝐾 ∈ HL ∧ 𝑃 ∈ 𝐴 ∧ 𝑄 ∈ 𝐴 ) ∧ ( 𝑅 ∈ 𝐴 ∧ 𝑆 ∈ 𝐴 ) ) → ( 𝑃 ∨ 𝑄 ) ∈ ( Base ‘ 𝐾 ) )
9	6 3	atbase	⊢ ( 𝑅 ∈ 𝐴 → 𝑅 ∈ ( Base ‘ 𝐾 ) )
10	9	ad2antrl	⊢ ( ( ( 𝐾 ∈ HL ∧ 𝑃 ∈ 𝐴 ∧ 𝑄 ∈ 𝐴 ) ∧ ( 𝑅 ∈ 𝐴 ∧ 𝑆 ∈ 𝐴 ) ) → 𝑅 ∈ ( Base ‘ 𝐾 ) )
11	6 3	atbase	⊢ ( 𝑆 ∈ 𝐴 → 𝑆 ∈ ( Base ‘ 𝐾 ) )
12	11	ad2antll	⊢ ( ( ( 𝐾 ∈ HL ∧ 𝑃 ∈ 𝐴 ∧ 𝑄 ∈ 𝐴 ) ∧ ( 𝑅 ∈ 𝐴 ∧ 𝑆 ∈ 𝐴 ) ) → 𝑆 ∈ ( Base ‘ 𝐾 ) )
13	6 2	latj12	⊢ ( ( 𝐾 ∈ Lat ∧ ( ( 𝑃 ∨ 𝑄 ) ∈ ( Base ‘ 𝐾 ) ∧ 𝑅 ∈ ( Base ‘ 𝐾 ) ∧ 𝑆 ∈ ( Base ‘ 𝐾 ) ) ) → ( ( 𝑃 ∨ 𝑄 ) ∨ ( 𝑅 ∨ 𝑆 ) ) = ( 𝑅 ∨ ( ( 𝑃 ∨ 𝑄 ) ∨ 𝑆 ) ) )
14	5 8 10 12 13	syl13anc	⊢ ( ( ( 𝐾 ∈ HL ∧ 𝑃 ∈ 𝐴 ∧ 𝑄 ∈ 𝐴 ) ∧ ( 𝑅 ∈ 𝐴 ∧ 𝑆 ∈ 𝐴 ) ) → ( ( 𝑃 ∨ 𝑄 ) ∨ ( 𝑅 ∨ 𝑆 ) ) = ( 𝑅 ∨ ( ( 𝑃 ∨ 𝑄 ) ∨ 𝑆 ) ) )