olemus
juurega puus tipuga c kaarteahela kaudu seotud kõrgema hierarhiaastme tipp, kusjuures eellased moodustavad ise ahela
= in a rooted tree, a vertex on the path from the root to the vertex
Vertex v is an ancestor of vertex w if and only if w is a descendant of v
http://tolweb.org/tree/home.pages/pictures/node3.jpg

vt ka
https://en.wikipedia.org/wiki/Ancestral_relation
https://en.wikipedia.org/wiki/Lowest_common_ancestor

vt ka
- eellane (2)
- järglane
- olemi x eellasvõti
- tipu v eellastipud