 i.e., \(\{g \mid \text{for some }h \in M(\varphi), g \sim_x h \}\), which can be described as: extend the set \(M(\varphi)\) with all \(x\)-variants. (The reference to ‘\(x\)’ may be felt as problematic, but Montague even eliminated this trace of non-compositionality by assigning appropriate meanings to variables; see Zimmermann and Sternefeld 2013, ch. 10, for pertinent details.) In general, in Montague semantics the meaning of an expression is a function which has as domain the triples \(\langle\)moment of time, possible world, assignment to variables\(\rangle\).