Let \((\Omega, \Sigma, \mu)\) be a meausurable space and \(\mu(\Omega)<\infty\). Then for \(p,q\in [1,\infty]\) with \(p>q\) there is a constant \(C>0\) which depends on \(\mu(\Omega)\), \(p\) and \(q\) such that
\begin{equation*} \lVert f\rVert_{L^q(\mu)}\le C\lVert f\rVert_{L^p(\mu)} \end{equation*}for all \(f\in L^p(\mu)\).
That means, that \(L^p(\mu)\) is continuously embedded in \(L^q(\mu)\), i.e. \(L^p(\mu)\hookrightarrow L^q(\mu)\).
Proof
This is a consequence of Hölders inequality
.