In this paper, we introduce the notion of extended of an ideal associated to a subset of an [Formula: see text]-algebra [Formula: see text] and investigate the related properties. A characterization of this extended ideal is given. We show that [Formula: see text] is stable ideal relative to [Formula: see text] such that [Formula: see text] if and only if [Formula: see text] is chain [Formula: see text]-algebra. Finally, the class [Formula: see text] of all stable ideals relative to [Formula: see text] is also a complete Heyting algebra, for an [Formula: see text]-algebra [Formula: see text].
Anatolij DvurečenskijOmid Zahiri
P. L. BelluceAda LettieriSalvatore Sessa