 The competing mathematical strategies are manifest in a more recent discussion concerning the mathematical foundations of quantum mechanics. In the preface to von Neumann’s (1955) treatise on that topic, he notes that Dirac provides a very elegant and powerful formal framework for quantum mechanics, but complains about the central role in that framework of an “improper function with self-contradictory properties,” which he also characterizes as a “mathematical fiction.” He is referring to the Dirac \(\delta\) function, which has the following incompatible properties: it is defined over the real line, is zero everywhere except for one point at which it is infinite, and yields unity when integrated over the real line. Von Neumann promotes an alternative framework, which he characterizes as being “just as clear and unified, but without mathematical objections.” He emphasizes that his framework is not merely a refinement of Dirac’s; rather, it is a radically different framework that is based on Hilbert’s theory of operators.