% Use standalone to generate PDF images
	% Recommended in slower machines and big files!
\documentclass{standalone}

	% Standard LaTeX libs
	%\usepackage{amssymb}

	% Custom TikZ
\usepackage{tikz}

	% Enable if using Overleaf to speed up compialtion times
	%\usepgfplotslibrary{external}
	%\tikzexternalize

\begin{document}
\begin{tikzpicture}
\draw[fill=blue, fill opacity=0.5] (-1,-1) circle (1cm);
\draw (-2,0) node {$\Omega_1$};

\draw[fill=green, fill opacity=0.5] (1,1) circle (1cm);
\draw (0,2) node {$\Omega_2$};

	% Dashed segment
\draw[thick, dashed] (-1,-1) .. controls (-1,0) and (0,1) .. (1,1);

	% Solid segments
\begin{scope}
	\clip (-1,-1) circle (1cm);
	\draw[thick] (-1,-1) .. controls (-1,0) and (0,1) .. (1,1);
\end{scope}

\begin{scope}
	\clip (1,1) circle (1cm);
	\draw[thick] (-1,-1) .. controls (-1,0) and (0,1) .. (1,1);
\end{scope}
\end{tikzpicture}
\end{document}