--- a/ChengsongTanPhdThesis/main.tex	Mon Aug 15 17:26:08 2022 +0200
+++ b/ChengsongTanPhdThesis/main.tex	Wed Aug 17 01:09:13 2022 +0100
@@ -81,6 +81,7 @@
    #3$%
 }
 \makeatother
+\def\checkmark{\tikz\fill[scale=0.4](0,.35) -- (.25,0) -- (1,.7) -- (.25,.15) -- cycle;} 
 
 \usepackage{amsthm}
 \usepackage{amssymb}
@@ -92,6 +93,7 @@
 \usepackage{tikz-cd}
 \usepackage{tikz}
 \usetikzlibrary{automata, positioning, calc}
+\usetikzlibrary{arrows}
 \usetikzlibrary{fit,
                 shapes.geometric,
 		patterns,