Brans-Dicke Theory on M₄times Z₂ Geometry

The gauge theory on $M_4\times Z_2$ geometry is applied to the Brans-Dicke(BD) theory, where $M_4$ is the four dimensional space-time and $Z_2$ is a discrete space with two points. This approach had been previously proposed by Konisi and Saito without recourse to noncommutative geometry(NCG). Since our approach is geometrically simpler and clearer than NCG, one can see more directly the effect of the $Z_2$ space in obtaining the BD theory.