Astronomer is a type of Worker. Astronomer is related to Telescope. you are likely to find Lens in/at/on Telescope. Objective is a type of Lens. 
Dog wants (to) Dig. Dog is a synonym of Tag. Tag is a synonym of Mark. Line is a type of Mark. 
Worker <--IsA-- Astronomer <--RelatedTo--> Telescope <--AtLocation-- Lens <--IsA-- Objective 
Dig <--Desires-- Dog <--Synonym--> Tag <--Synonym--> Mark <--IsA-- Line 