[bioontology-support] How a tree is determined from a DAG?

[Michael Liu]

Hi,

I see some class has more than one superclasses, which means that the
class hierarchy should be a directed acyclic graph (DAG) instead of a
tree. But the panel on the left shows a tree structure. Is there tree
draw by using only the first subClassOf property of each class?
Thanks.

https://bioportal.bioontology.org/ontologies/EFO/?p=classes&conceptid=http%3A%2F%2Fwww.orpha.net%2FORDO%2FOrphanet_64746

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Best wishes,
Michael