Reverted dummy changes to notebooks

Author: kvrigor

chapter1/poisson.ipynb

@@ -7,6 +7,7 @@
    "source": [
     "# Your first code using SymPDE & PsyDAC\n",
     "\n",
+    "*Author: Ahmed Ratnani*\n",
     "We start by writing our first example using SymPDE.\n",
     "Let $\\Omega := (0,1)^2$. We consider the Poisson problem with homogeneous Dirichlet boundary conditions.  \n",
     "\n",

chapter2/poisson.ipynb

@@ -18,7 +18,7 @@
     "\\end{align}\n",
     "$$\n",
     "\n",
-    "## Variational Form\n",
+    "## Variational Formulation\n",
     "\n",
     "An $H^1$-conforming variational formulation of reads\n",
     "\n",

chapter4/poisson-two-subdomains-nitsche.ipynb

@@ -21,7 +21,7 @@
     "\\end{align}\n",
     "$$\n",
     "\n",
-    "## Variational Form\n",
+    "## Variational Formulation\n",
     "\n",
     "The variational formulation reads\n",
     "\n",