In mathematics, the predual of an object D is an object P whose dual space is D.
For example, the predual of the space of bounded operators is the space of trace class operators, and the predual of the space L<sup>âÂÂ</sup>(R) of essentially bounded functions on R is the Banach space L<sup>1</sup>(R) of integrable functions.
In operator algebra, if a dual Banach/operator space is realized as the dual of some Banach space , then is called the predual of (Formally: ) The predual induces a weak topology on , under which algebra operations are separately weak continuous.