// global context
digraph {
	context -> "context; global context" [label="" arrowhead=normal]
	sally -> trude [label=mother arrowhead=normal]
	sally -> tom [label=father arrowhead=normal]
	erica -> trude [label=mother arrowhead=normal]
	erica -> tom [label=father arrowhead=normal]
	trude -> sara [label=mother arrowhead=normal]
	trude -> sam [label=father arrowhead=normal]
	tom -> ruth [label=mother arrowhead=normal]
	tom -> mike [label=father arrowhead=normal]
	ruth -> gina [label=mother arrowhead=normal]
	mike -> mary [label=mother arrowhead=normal]
	mike -> mark [label=father arrowhead=normal]
}