Structure of the Kobayashi-Maskawa matrix

The measure of $\mathrm{CP}$ violation $J$ in the Kobayashi-Maskawa (KM) model is estimated by expansion around $\left|V_{\mathrm{ub}}\right|=0\mathrm{}$. We obtain that $\mathrm{}\left|J\right|\mathrm{}\simeq \left|V_{\mathrm{us}}\mathrm{}\right|\left|\mathrm{}{V}_{\mathrm{cb}}\mathrm{}\right|\left|\mathrm{}{V}_{\mathrm{ub}}\right|$ and the KM asymmetry parameter $\omega \simeq -{\left|V_{\mathrm{us}}\right|}^2{\left|V_{\mathrm{cb}}\right|}^2$. We discuss the implication of imposing this condition on the KM matrix elements, on the top-quark mass using the measurements of ${\varepsilon }_K$, $B_d^0-{\overline{B}}_d^0$ mixing, $\left|V_{\mathrm{cb}}\right|$, and $|\frac{V_{\mathrm{ub}}|}{\left|V_{\mathrm{cb}}\right|}$. A comparison with the symmetric KM matrix is made.