The USPTO treats prior art references with predicted properties or prophetic examples as potentially valid prior art. According to MPEP 2121.04: "A reference that contains a detailed description of a specific embodiment, even if the embodiment has not been prepared or tested, may be sufficient to anticipate or render obvious a claimed invention." This means that: Predicted properties and prophetic examples can be used as prior art. The reference doesn't need to show actual reduction to practice. The described embodiment should be enabling to a person of ordinary skill in the art. However, if an applicant provides evidence that the prophetic example is not enabling, the examiner should reconsider the rejection based on that reference. To learn more: prior art prophetic examples predicted properties patent examination