> In mathematics and physics, Penrose graphical notation or tensor diagram notation is a (usually handwritten) visual depiction of multilinear functions or tensors proposed by Roger Penrose in 1971.[1] A diagram in the notation consists of several shapes linked together by lines.
Penrose graphical notation (tensor diagram notation) of a matrix product state of five particles
The notation widely appears in modern quantum theory, particularly in matrix product states and quantum circuits. In particular, Categorical quantum mechanics which includes ZX-calculus is a fully comprehensive reformulation of quantum theory in terms of Penrose diagrams, and is now widely used in quantum industry.
> The notation has been studied extensively by Predrag Cvitanović, who used it, along with Feynman's diagrams and other related notations in developing "birdtracks", a group-theoretical diagram to classify the classical Lie groups.[2] Penrose's notation has also been generalized using representation theory to spin networks in physics, and with the presence of matrix groups to trace diagrams in linear algebra.
1: https://github.com/xh-diagrams/xhorizon
2: https://github.com/einsteinpy/einsteinpy/issues/480
There's a 'spacetime' GH topic: https://github.com/topics/spacetime
/? spacetime diagrams site:github.com : https://www.google.com/search?q=spacetime+diagrams+site%3Agi...