(a + b − c)^n = (c − a)(c − b)g_1(n)

  => a + b − c = [(c − a)(c − b)g_1(n)]^(1/n)

  => g_1(n) | a + b - c

My issue at the moment is with a line at the bottom of p.4, which effectively says that if k^n = xy for integers k, n, x, y, then k must be a multiple of y. Unless I'm missing something this is clearly false, for example 2^4 = 4 x 4.