 where \(\delta(p/\phi)\) and \(\delta(p/\psi)\) are the formulas obtained by substituting respectively \(\phi\) and \(\psi\) for \(p\) in \(\delta\). This replacement property is taken by some authors as the formal counterpart of Frege’s principle of compositionality for truth. Logics satisfying this strong replacement property are called Fregean in Font &amp; Jansana 1996 and are thoroughly studied in Czelakowski &amp; Pigozzi 2004a, 2004b.