A new approach to generalized metric spaces

To overcome fundamental flaws in B. C. Dhage's theory of generalized metric spaces, flaws that invalidate most of the results claimed for these spaces, we introduce an alternative more robust generalization of metric spaces. Namely, that of a G-metric space, where the G-metric satisfies the axioms: (1) G(x, y, z) = 0 if x = y = z; (2) 0 < G(x, x, y) ; whenever x =/= y, (3) G(x, x, y) <= G(x, y, z) whenever z =/= y, (4) G is a symmetric function of its three variables, and (5) G(x, y, z) <= G(x, a, a) + G(a, y, z).