ϕ I = min f ∈ f ⊥ i ( ϕ f ) {\displaystyle \phi _{I}=\min \limits _{{\textit {f}}\in {\textit {f}}\perp i}(\phi _{f})}
∏ 0 < i < m k = 1 {\displaystyle \prod _{\begin{array}{c}0<i<m\\k=1\end{array}}}
