digraph G {
    margin=0;

    p [style=bold, label="paper"];
    f [label="file-01"];
    r [label="read-01"];
    b [label="before"];

    f->b [label=time];
    b->r [label="op1"];

    f->i [label="ARG0"];
    f->p [label="ARG1"];
    r->i [label="ARG0"];
    r->p [label="ARG1"];

}
