$\textbf{Open mapping theorem}$
Every bounded linear operator from a Banach space onto a Banach space is an open mapping, i.e. maps open sets to open sets.
$\textbf{Open mapping theorem}$
Every bounded linear operator from a Banach space onto a Banach space is an open mapping, i.e. maps open sets to open sets.
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Every bounded linear operator from a Banach space onto a Banach space is an open mapping, i.e. maps open sets to open sets.