 Much of what was said above about the need to constrain what counts as meaning applies to structure as well. Janssen (1983) has a proof that we can turn any meaning assignment on a recursively enumerable set of expressions into a compositional one, as long as we can replace the syntactic operations with different ones. If we insist—as we should—that any acceptable semantic theory must respect what syntax tells us about the structure of complex expressions, this result says nothing about the possibility of providing an adequate compositional semantics; cf. Westerståhl  1998.[8]  The moral of the result is that although commitment to compositionality requires allegiance to no particular sect of syntacticians, one cannot be oblivious to syntactic evidence in semantic theorizing.