dot -Tsvg  09-graph1.gv > 09-graph1.svg
dot -Tsvg  09-graph2.gv > 09-graph2.svg
dot -Tsvg  09-graph3.gv > 09-graph3.svg
dot -Tsvg  09-graph4.gv > 09-graph4.svg
dot -Tsvg  09-graph5.gv > 09-graph5.svg
dot -Tsvg  09-graph6.gv > 09-graph6.svg