Full Idea
With a basic parthood relation, we can formally define various mereological predicates, such as overlap, underlap, proper part, over-crossing, under-crossing, proper overlap, and proper underlap.
Clarification
See Idea 10649 for the parthood relation
Gist of Idea
The parthood relation will help to define at least seven basic predicates
Source
Achille Varzi (Mereology [2003], 2.2)
Book Reference
'Stanford Online Encyclopaedia of Philosophy', ed/tr. Stanford University [plato.stanford.edu], p.6
A Reaction
[Varzi offers some diagrams, but they need interpretation]
Related Idea
Idea 10649 'Part' stands for a reflexive, antisymmetric and transitive relation [Varzi]