Soviet is a type of Person. Person is related to Date. Decade is a type of Date. Year is part of Decade. 
Butter is related to Bread. Bread is related to Dough. Dough is related to Flour. 
Soviet --IsA--> Person <--RelatedTo--> Date <--IsA-- Decade <--PartOf-- Year 
Butter <--RelatedTo--> Bread <--RelatedTo--> Dough <--RelatedTo--> Flour 