野村数学研究所

\[ \lim_{k\rightarrow\infty}\left\langle \boldsymbol{x}_{k},\boldsymbol{y}_{k}\right\rangle =\left\langle \boldsymbol{x},\boldsymbol{y}\right\rangle \]

\[ \left\langle f\left(\boldsymbol{x}\right),f\left(\boldsymbol{y}\right)\right\rangle =\left\langle \boldsymbol{x},\boldsymbol{y}\right\rangle \]

\[ \left\langle \boldsymbol{x},\boldsymbol{y}\right\rangle _{V}=\left\langle f\left(\boldsymbol{x}\right),f\left(\boldsymbol{y}\right)\right\rangle _{W} \]

\[ \boldsymbol{b}_{m}=\frac{\boldsymbol{b}'_{m}}{\left\Vert \boldsymbol{b}'_{m}\right\Vert },\boldsymbol{b}'_{m}=\boldsymbol{a}_{m}-\sum_{k=1}^{m-1}\left\langle \boldsymbol{a}_{m},\frac{\boldsymbol{b}'_{k}}{\left\Vert \boldsymbol{b}'_{k}\right\Vert }\right\rangle \frac{\boldsymbol{b}'_{k}}{\left\Vert \boldsymbol{b}'_{k}\right\Vert } \]

\[ \left\langle \boldsymbol{x},\boldsymbol{y}\right\rangle =\sum_{k=1}^{n}x_{k}\overline{y_{k}} \]

\[ W^{\bot}=\left\{ \boldsymbol{x}\in V;\forall\boldsymbol{y}\in W,\left\langle \boldsymbol{x},\boldsymbol{y}\right\rangle =0\right\} \]

\[ \left\langle \boldsymbol{x},\boldsymbol{y}\right\rangle =\sum_{k=1}^{n}x_{k}\overline{y_{k}} \]

\[ \left\langle \boldsymbol{0},\boldsymbol{x}\right\rangle =\left\langle \boldsymbol{x},\boldsymbol{0}\right\rangle =0 \]

\[ \sum_{k=1}^{\infty}\left|\left\langle \boldsymbol{x},\boldsymbol{e}_{k}\right\rangle \right|^{2}=\left\Vert \boldsymbol{x}\right\Vert ^{2} \]

\[ \sum_{k=1}^{\infty}\left|\left\langle \boldsymbol{x},\boldsymbol{a}_{k}\right\rangle \right|^{2}\leq\left\Vert \boldsymbol{x}\right\Vert ^{2} \]

\[ \forall\boldsymbol{x}\in H,\boldsymbol{x}=\sum_{k}\left\langle \boldsymbol{x},\boldsymbol{e}_{k}\right\rangle \boldsymbol{e}_{k} \]

完備なノルム空間をバナッハ空間という。

\[ \forall k,\left\langle \boldsymbol{x},\boldsymbol{e}_{k}\right\rangle =0\rightarrow\boldsymbol{x}=\boldsymbol{0} \]

\[ \text{ノルム空間}+\text{中線定理}\Leftrightarrow\text{内積空間} \]

\[ \left|\left\langle \boldsymbol{x},\boldsymbol{y}\right\rangle \right|\leq\left\Vert \boldsymbol{x}\right\Vert \left\Vert \boldsymbol{y}\right\Vert \]

\[ \left(V,\left\langle \cdot,\cdot\right\rangle \right) \]