Rice is related to Food. Food is related to Slice. Slice is the opposite of Whole. 
Piece is a type of Item. Item is related to Paper. Paper is related to Plate. Plate is related to Cake. 
Rice <--RelatedTo--> Food <--RelatedTo--> Slice <--Antonym--> Whole 
Piece --IsA--> Item <--RelatedTo--> Paper <--RelatedTo--> Plate <--RelatedTo--> Cake 