- occurs_as_def
- occurs_as_use
- occurs = occurs_a_def | occurs_as_use
- is_contained_in
- contains = is_contained_in^T
- is_child_of = has_parent
- has_children
- is_child_of ⊆ has_parent ; has_children
- classifies
- has_tags = is_classified = classifies^T
- classifies ; has_tags ⊆ id ？
- has_id
- refers_as 三項関係
- represents 代理
ツリー構造の関数的関係
- parent
- childList
- firstChild
- nextSibling
- prevSibling
- eldestSibling
