Source: J. Math. Soc. Japan Volume 60, Number 2
(2008), 511-549.
The completion of a (normed) $C^*$-algebra $\A_0[\| \cdot \|_0]$ with respect to a locally convex topology $\tau$ on $\A_0$ that makes the multiplication of $\A_0$ separately continuous is, in general, a quasi $*$-algebra, and not a locally convex $*$-algebra [10], [15]. In this way, one is led to consideration of locally convex quasi $C^*$-algebras, which generalize $C^*$-algebras in the context of quasi $*$-algebras. Examples are given and the structure of these relatives of $C^*$-algebras is investigated.
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