Explicit is similar to Express. Express is related to Paint. Paint is related to Roll. 
Session is a type of Conference. Session is related to Lesson. Lesson is related to Course. Course is related to River. 
Explicit <--SimilarTo--> Express <--RelatedTo--> Paint <--RelatedTo--> Roll 
Conference <--IsA-- Session <--RelatedTo--> Lesson <--RelatedTo--> Course <--RelatedTo--> River 