Mondrian Diagrams are a refinement of Feynman Diagrams for visualizing nested quantum electrodynamic (QED) interactions. The Diagram on the left shows the annihilation of a positron & an electron into a photon & the spontaneous decay of the photon into a new electron/positron pair. The diagram in the center is a Mondrian Diagram from a recently published paper, which suggests that nested interactions in low-energy instances of this annihilation/creation loop may create gravity.

From what I can tell, the term “Mondrian Diagram” was imported to QED from Algebraic Topology.