UAF13 — Definition of Tuple is that for a Relationship (Not a Tuple)

Fig 7:3
Definition - 'A Tuple denotes a relationship that exists between elements.'

This is incorrect - it defines a relationship (as it says). A tuple has to also include the start and finish nodes as well to form the smallest tuple - a triple.

Looking at the diagrams it is the legend definition that is incorrect because the green coloured elements are relationships not triples. A clue is in Fig 8:28 on p49 ActualResourceRelationship is identified in green and is clearly just a relationship.