Proof. (1) Let a ∈ L∩B. Since T is intra-regular, there exist s, t, x, y, z ∈
T such that a ≤ xsazaty. Thus a ≤ xsazaty ≤ xs(xsazaty)zaty =
xsxsaz(atyza)ty ∈ T T T T LT(BTTTB)T T ⊆ T T LT BT T ⊆ LT BT T. Thus
L ∩ B ⊆ (LT BT T].
Conversely, let a ∈ T. Then a ∈ B(a) and a ∈ L(a), we have a ∈ B(a) ∩
L(a). By hypothesis