SourceGraph	: graph number of source
	      	  graph; Identical to graph 
		  number for intra-graph edges
SourceNode	: node number of source node
TargetGraph	: graph number of target
	      	  graph; Identical to graph 
		  number for intra-graph edges
TargetNode	: node number of target node
EdgeLabel	: label of created/deleted edge
SourceExists	: states whether the source node
		  still exists on action
		  execution 
TargetExists	: states whether the target node
		  still exists on action
		  execution 
