Some examples of lifting problems from quotient algebras

Abstract

We consider three lifting questions: Given a $C\sp{*}$-algebra $I$, if there is a unital $C\sp{*}$-algebra $A$ contains $I$ as an ideal, is every unitary from $A/I$ lifted to a unitary in $A$? is every unitary from $A/I$ lifted to an extremal partial isometry? is every extremal partial isometry from $A/I$ lifted to an extremal partial isometry? We show several constructions of $I$ which serve as working examples or counter-examples for above questions.

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