Best approximations, distance formulas and orthogonality in C*-algebras

Priyanka Grover, Sushil Singla

For a unital $C^{\ast }$-algebra $\mathcal{A}$ and a subspace $\mathcal{B}$ of $\mathcal{A}$, a characterization for a best approximation to an element of $\mathcal{A}$ in $\mathcal{B}$ is ob…