\begin {array}{lcl} \mathbf {E} & \triangleq & \Sigma \rightarrow \mathbb {Z}\textcolor {blue}{\ \uplus \ \mathbf {C}}\\ \mathbf {B} & \triangleq & \Sigma \rightarrow \mathbb {B} \\ \mathbf {C} & \triangleq & \Sigma \rightarrow \Sigma \\[0.2em] \Sigma & \triangleq & \mathcal {V} \rightarrow \mathbb {Z}\textcolor {blue}{\ \uplus \ \mathbf {C}} \end {array}

x [n] e^{i 2 π n s / N} ⟷ X [k - s] .

$x[n]e^{i2\pi ns/N}\longleftrightarrow X[k-s].$

⃗ \nabla \times ⃗ 𝐹 = (𝜕 𝐹 𝑧 𝜕 𝑦 - 𝜕 𝐹 𝑦 𝜕 𝑧) 𝐢 + (𝜕 𝐹 𝑥 𝜕 𝑧 - 𝜕 𝐹 𝑧 𝜕 𝑥) 𝐣 + (𝜕 𝐹 𝑦 𝜕 𝑥 - 𝜕 𝐹 𝑥 𝜕 𝑦) 𝐤