LaTeX fix

Author: eduardosalaz

authors/eduardosalaz/bilevel/bilevel_markets.ipynb

@@ -270,7 +270,9 @@
         "#### Objective Function\n",
         "\n",
         "$$\n",
+        "\\begin{align}\n",
         "\\max_{\\substack{\\text{bid}_i, p_i, \\lambda \\\\ \\mu_i^-, \\mu_i^+, \\nu}} \\quad \\sum_{i \\in \\mathcal{S}} \\left( \\lambda \\cdot p_i - c_i \\cdot p_i - q_i \\cdot p_i^2 \\right) \\tag{MPEC-Obj}\n",
+        "\\end{align}\n",
         "$$\n",
         "\n",
         "#### Constraints\n",