Invest is a type of Spend. Invest is etymologically related to Investigate. Explore is a type of Investigate. Explore is a synonym of Seek. 
you are likely to find Shelf in/at/on House. House is a type of Audience. 
Spend <--IsA-- Invest --EtymologicallyRelatedTo--> Investigate <--IsA-- Explore <--Synonym--> Seek 
Shelf --AtLocation--> House --IsA--> Audience 