 However, the presence of 1 negative power among the 3 powers "pl", "pm", "pn" results in appearance of terms from "P"αβ with an order greater than "t"−2.If the negative power is "pl" ("pl" = "p"1 < 0), then "P"αβ contains the coordinate function λ and become

Here, the second terms are of order "t"−2("pm" + "pn" − "pl") whereby "pm" + "pn" − "pl" = 1 + 2 |"pl"| > 1.To remove these terms and restore the metric , it is necessary to impose on the coordinate functions the condition λ = 0.