documentclass[tikz]{standalone}
begin{document}
begin{tikzpicture}[x=1.5cm]
foreach i in {1,2} draw (i,-.2) -- (i,3.2);
foreach i in {0,1,2,3} draw (0,i) -- (3,i);
foreach x/y in {
    .5/0,
    .4/2,
    .6/2,
    .5/2.5
} fill (x,y) circle (2pt);
end{tikzpicture}
end{document}