Defining $A^+$ as the pseudoinverse of matrix $A$, what can be said about $AA^+$ if $A$ is a real matrix? What if $A$ is also symmetric?
The reason I am asking this is that I want to see why the following dual problem definition is true.$^\color{magenta}{\star}$
$\color{magenta}{\star}$ Mahdi Jafari Siavoshani, Duality in General Programs, Convex Optimization, Sharif University of Technology, Spring 2023.
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