chdmm4

Description: De Morgan's law for meet in a Hilbert lattice. (Contributed by NM, 21-Jun-2004) (New usage is discouraged.)

		Ref	Expression
	Assertion	chdmm4	$⊢ (A \in C_{ℋ} \land B \in C_{ℋ}) \to ⊥ (⊥ (A) \cap ⊥ (B)) = A \lor_{ℋ} B$

Step	Hyp	Ref	Expression
1		choccl	$⊢ B \in C_{ℋ} \to ⊥ (B) \in C_{ℋ}$
2		chdmm2	$⊢ (A \in C_{ℋ} \land ⊥ (B) \in C_{ℋ}) \to ⊥ (⊥ (A) \cap ⊥ (B)) = A \lor_{ℋ} ⊥ (⊥ (B))$
3	1 2	sylan2	$⊢ (A \in C_{ℋ} \land B \in C_{ℋ}) \to ⊥ (⊥ (A) \cap ⊥ (B)) = A \lor_{ℋ} ⊥ (⊥ (B))$
4		ococ	$⊢ B \in C_{ℋ} \to ⊥ (⊥ (B)) = B$
5	4	adantl	$⊢ (A \in C_{ℋ} \land B \in C_{ℋ}) \to ⊥ (⊥ (B)) = B$
6	5	oveq2d	$⊢ (A \in C_{ℋ} \land B \in C_{ℋ}) \to A \lor_{ℋ} ⊥ (⊥ (B)) = A \lor_{ℋ} B$
7	3 6	eqtrd	$⊢ (A \in C_{ℋ} \land B \in C_{ℋ}) \to ⊥ (⊥ (A) \cap ⊥ (B)) = A \lor_{ℋ} B$

Metamath Proof Explorer