documentclass{article}

usepackage{centernot}
usepackage{amsmath}

begin{document}

begin{equation}
(forall pi_{i},pi_{j} in mathcal{P}) [pi_{i} centernotll pi_{j} wedge pi_{j} centernotll pi_{i}].
end{equation}

end{document}

documentclass{article}

usepackage{graphicx}
usepackage{mathptmx}
usepackage{centernot}
usepackage{amsmath}
usepackage{tikz}
usepackage{amssymb}
usepackage{amsthm}
usepackage{enumitem}
usepackage{mathtools}
usepackage{mathrsfs}
usepackage{mathtools}
usepackage{tabularx}
usepackage{fdsymbol}
usepackage{rotating}
usepackage{nth}
usepackage{array}
usepackage{makecell}
usepackage{soul}
usepackage[normalem]{ulem}
usepackage{algorithm}
usepackage{algorithmicx,algpseudocode}
usepackage[top=2cm, left = 2cm, right = 2cm, bottom = 2cm]{geometry}
usepackage{stackengine}
usepackage{braket}

begin{document}

begin{equation}
(forall pi_{i},pi_{j} in mathcal{P}) [pi_{i} centernotll pi_{j} wedge pi_{j} centernotll pi_{i}].
end{equation}

end{document}