CPT Invariance As Three Branchial Reflections

CPT invariance has a clean formulation in these models: charge conjugation is an inversion (reflection) in branchial space, parity is a reflection of physical space, and time reversal is a reflection in time, so CPT invariance corresponds to the multiway causal graph being invariant under reflection in all three directions, though it has not yet been shown that the models necessarily exhibit CPT invariance.