documentclass[a4paper,twoside,10pt]{book}
usepackage {tikz}
usetikzlibrary {positioning,graphs,calc,decorations.pathmorphing,shapes,arrows.meta,arrows,shapes.misc}
usepackage{tikz-cd}
usepackage{greektex}
usepackage[american,greek,greek.polytoniko]{babel}


begin{document}

begin{center}
tikzset{every loop/.style={min distance=15mm,looseness=10}}
begin{tikzpicture}[-latex ,auto ,node distance =0.7cm and 5cm, on grid,semithick ,
state/.style ={circle, draw, color=blue , fill=blue, text=white , minimum width =0.2 cm}]
node[state] (a1) [label=left:$alpha_1$]{};
node[state] (a2) [below =of a1][label=left:$alpha_2$]{};
node[state] (a3) [below =of a2][label=left:$alpha_3$]{};
node[state] (adots) [below =of a3][label=left:$vdots$]{};
node[state] (an) [below =of adots][label=left:$alpha_n$]{};
node[state] (b1) [right =of a1][label=right:$beta_1$]{};
node[state] (b2) [below =of b1][label=right:$beta_2$]{};
node[state] (b3) [below =of b2][label=right:$beta_3$]{};
node[state] (bdots) [below =of b3][label=right:$vdots$]{};
node[state] (bn) [below =of bdots][label=right:$beta_n$]{};
node[state] (x1) [below =of an,yshift=-0.5cm][label=left:$x_1$]{};
node[state] (x2) [below =of x1][label=left:$x_2$]{};
node[state] (x3) [below =of x2][label=left:$x_3$]{};
node[state] (xdots) [below =of x3][label=left:$vdots$]{};
node[state] (xn) [below =of xdots][label=left:$x_n$]{};
node[state] (y1) [below =of bn,yshift=-0.5cm][label=right:$y_1$]{};
node[state] (y2) [below =of y1][label=right:$y_2$]{};
node[state] (y3) [below =of y2][label=right:$y_3$]{};
node[state] (ydots) [below =of y3][label=right:$vdots$]{};
node[state] (yn) [below =of ydots][label=right:$y_n$]{};
path [dashed] (a1) edge (b1); path [dashed] (b2) edge (a2);
path [dashed] (b3) edge (a3); path [dashed] (an) edge (bn);
path (x1) edge (y1); path (y2) edge (x2);
path (y3) edge (x3); path (xn) edge (yn);
end{tikzpicture}
end{center}
end{document}