As was discussed in the context of the foundations of quantum mechanics, the mathematical boundaries of a theoretician's models are shaped to help understand or rationalize experimental reality. Once understood, theoretical models are routinely extended¾usually to make the model closer in its ability to describe reality (a refinement in the ability of the model to resolve the phenomena to a higher experimental precision). Sometimes though models are extended in abstract ways, these abstractions might represent mathematical tractability¾such extensions afford no additional experimental insight but offer interesting mathematical excursions.