n-バイン場：場の方程式
\displaystyle \frac {\partial ^2 k_{\beta\alpha}}{(\partial x^{\mu})^2}- \frac {\partial ^2 k_{\mu\alpha}}{\partial x^{\mu} \partial x^{\beta}} + \frac {\partial ^2 k_{\alpha\mu}}{\partial x^{\mu} \partial x^{\beta}} - \frac {\partial ^2 k_{\beta\mu}}{\partial x^{\mu} \partial x^{\alpha}} = 0
おまけ
\Gamma^k_{ij}
