The Parisi–Sourlas construction originally aimed at "dimensional reduction" proposed in 1976 by Amnon Aharony, Yoseph Imry, and Shang-keng Ma who proved that to all orders in perturbation expansion, the critical exponents in a d -dimensional (4 < d < 6) system with short-range exchange and a random quenched field are the same as those of a (d –2)-dimensional pure system. Their arguments indicated that the "Feynman diagrams which give the leading singular behavior for the random case are identically equal, apart from combinatorial factors, to the corresponding Feynman diagrams for the pure case in two fewer dimensions."