Sur les elements bornants et les ideaux formes d'elements bornants joints dans les algebres bornologiques

Bounding elements and ideals consisting of joint bounding elements were essential tools in the study of permanent singularity in the class of all bornological algebras ([1], [6], [7], [8] and [12]). In this paper we give some important properties of these two notions. Especially, we compare boundings elements with some similar known notions such as bornological divisors of zero and topological divisors of zero. Then we show that these elements can be seen as algebraic divisor of zero in some suitable extension of the initial algebra. This result is analogous to a well-known result of Żelazko [11] concerning topological divisors of zero in Banach algebras. Finaly, we show that a maximal ideal is a prime ideal among ideals consisting of joint bounding elements. This is analougous to the result given in [4] concerning ideals consisting of joint topological divisors of zero in the case of Banach algebras.