LaTeX Forum

\documentclass[11pt]{article}
\usepackage[T1]{fontenc}
\usepackage{mathtools}
\usepackage{amsfonts}

\DeclareMathOperator*{\Min}{\mathbf{Min}}

\begin{document}
  \begin{align*}
    & \Min_{x_t\in\mathcal{X}(x_t-1),\xi_t} \\
    & \begin{Bmatrix}
      \displaystyle\inf_{x_{t+1},\ldots,x_T} & \mathbb{F}_t\big(f_t(x_t,\xi_t),f_{t+1}(x_{t+1},\xi_{t+1}),\ldots,f_T(x_T,\xi_T) | \xi_{[1,t]}\big)\\
      \text{s. t.} & x_\tau\in\mathcal{X}(x_\tau-1),\xi_\tau,\ \tau = t+1,\ldots,T
    \end{Bmatrix}
  \end{align*}

  \begin{align*}
    & \Min_{x_t\in\mathcal{X}(x_t-1),\xi_t} \\
    & \left\{\begin{array}{@{}cl@{}}
      \displaystyle\inf_{x_{t+1},\ldots,x_T} & \mathbb{F}_t\big(f_t(x_t,\xi_t),f_{t+1}(x_{t+1},\xi_{t+1}),\ldots,f_T(x_T,\xi_T) | \xi_{[1,t]}\big)\\
      \text{s. t.} & x_\tau\in\mathcal{X}(x_\tau-1),\xi_\tau,\ \tau = t+1,\ldots,T
    \end{array}\right\}
  \end{align*}
\end{document}