digraph G {
N1 -> N2
N1 -> N6
N2 -> N3
N2 -> N4
N1 [ label="/",  shape="parallelogram"]
N3 [ label="a[i]",  shape="box"]
N2 [ label="-",  shape="parallelogram"]
N6 [ label="(cached)",  shape="box"]
N4 [ label="(cached)",  shape="box"]
}