- where:
- x: node of graph database as invisible task
- [:SPLIT]: a split relation of activities (XORSplit, ORSplit or ANDSplit)
- [:JOIN]: a join relation of activities (XORJoin, ORJoin or ANDJoin)
- [:INVISIBLE]: a temporary relation to determine the need for invisible tasks
- size(): the number of occurrences of the specified relation in the graph database