Theorem oldmm2

Description: De Morgan's law for meet in an ortholattice. ( chdmm2 analog.) (Contributed by NM, 6-Nov-2011)

	Ref	Expression
Hypotheses	oldmm1.b	⊢ 𝐵 = ( Base ‘ 𝐾 )
	oldmm1.j	⊢ ∨ = ( join ‘ 𝐾 )
	oldmm1.m	⊢ ∧ = ( meet ‘ 𝐾 )
	oldmm1.o	⊢ ⊥ = ( oc ‘ 𝐾 )
Assertion	oldmm2	⊢ ( ( 𝐾 ∈ OL ∧ 𝑋 ∈ 𝐵 ∧ 𝑌 ∈ 𝐵 ) → ( ⊥ ‘ ( ( ⊥ ‘ 𝑋 ) ∧ 𝑌 ) ) = ( 𝑋 ∨ ( ⊥ ‘ 𝑌 ) ) )

Proof

Step	Hyp	Ref	Expression
1		oldmm1.b	⊢ 𝐵 = ( Base ‘ 𝐾 )
2		oldmm1.j	⊢ ∨ = ( join ‘ 𝐾 )
3		oldmm1.m	⊢ ∧ = ( meet ‘ 𝐾 )
4		oldmm1.o	⊢ ⊥ = ( oc ‘ 𝐾 )
5		olop	⊢ ( 𝐾 ∈ OL → 𝐾 ∈ OP )
6	1 4	opoccl	⊢ ( ( 𝐾 ∈ OP ∧ 𝑋 ∈ 𝐵 ) → ( ⊥ ‘ 𝑋 ) ∈ 𝐵 )
7	5 6	sylan	⊢ ( ( 𝐾 ∈ OL ∧ 𝑋 ∈ 𝐵 ) → ( ⊥ ‘ 𝑋 ) ∈ 𝐵 )
8	7	3adant3	⊢ ( ( 𝐾 ∈ OL ∧ 𝑋 ∈ 𝐵 ∧ 𝑌 ∈ 𝐵 ) → ( ⊥ ‘ 𝑋 ) ∈ 𝐵 )
9	1 2 3 4	oldmm1	⊢ ( ( 𝐾 ∈ OL ∧ ( ⊥ ‘ 𝑋 ) ∈ 𝐵 ∧ 𝑌 ∈ 𝐵 ) → ( ⊥ ‘ ( ( ⊥ ‘ 𝑋 ) ∧ 𝑌 ) ) = ( ( ⊥ ‘ ( ⊥ ‘ 𝑋 ) ) ∨ ( ⊥ ‘ 𝑌 ) ) )
10	8 9	syld3an2	⊢ ( ( 𝐾 ∈ OL ∧ 𝑋 ∈ 𝐵 ∧ 𝑌 ∈ 𝐵 ) → ( ⊥ ‘ ( ( ⊥ ‘ 𝑋 ) ∧ 𝑌 ) ) = ( ( ⊥ ‘ ( ⊥ ‘ 𝑋 ) ) ∨ ( ⊥ ‘ 𝑌 ) ) )
11	1 4	opococ	⊢ ( ( 𝐾 ∈ OP ∧ 𝑋 ∈ 𝐵 ) → ( ⊥ ‘ ( ⊥ ‘ 𝑋 ) ) = 𝑋 )
12	5 11	sylan	⊢ ( ( 𝐾 ∈ OL ∧ 𝑋 ∈ 𝐵 ) → ( ⊥ ‘ ( ⊥ ‘ 𝑋 ) ) = 𝑋 )
13	12	3adant3	⊢ ( ( 𝐾 ∈ OL ∧ 𝑋 ∈ 𝐵 ∧ 𝑌 ∈ 𝐵 ) → ( ⊥ ‘ ( ⊥ ‘ 𝑋 ) ) = 𝑋 )
14	13	oveq1d	⊢ ( ( 𝐾 ∈ OL ∧ 𝑋 ∈ 𝐵 ∧ 𝑌 ∈ 𝐵 ) → ( ( ⊥ ‘ ( ⊥ ‘ 𝑋 ) ) ∨ ( ⊥ ‘ 𝑌 ) ) = ( 𝑋 ∨ ( ⊥ ‘ 𝑌 ) ) )
15	10 14	eqtrd	⊢ ( ( 𝐾 ∈ OL ∧ 𝑋 ∈ 𝐵 ∧ 𝑌 ∈ 𝐵 ) → ( ⊥ ‘ ( ( ⊥ ‘ 𝑋 ) ∧ 𝑌 ) ) = ( 𝑋 ∨ ( ⊥ ‘ 𝑌 ) ) )