  In this paper, a functional model of interactions in quantum theory (QT) is
proposed. A functional model describes the dynamic evolution of a physical
system in terms of process steps and intermediate states. That is, it describes
how things function. The proposed functional model of QT interactions was
developed in the context of the author's work toward a computer model of QT
with the goal of supporting the largest possible scope of QT concepts. In QT,
the results of interactions are computed using quantum field theory (QFT).
Therefore, the proposed functional model of interactions is based on QFT. There
are a number of important QT concepts, such as measurement, entanglement, and
decoherence, that are related to interactions. The functional model of
interactions also addresses these phenomena.
