 \(\Gamma \vdash_{\bL_{\bK}^{\phi} } \phi \txtiff\) for every \(\bA \in \bK(\bL)\) and every valuation v on \(\bA\), if \(\bv(\psi) = \phi^{\bA}\) for all \(\psi \in \Gamma \), then \(\bv(\phi) = \phi^{\bA}\).