Little is related to Form. Form is a synonym of Invent. 
one thing you do when you Writing is Define. one thing you do when you Writing is Expand. Expand is a synonym of Spread. Invasion is a type of Spread. 
Little <--RelatedTo--> Form <--Synonym--> Invent 
Define <--HasSubevent-- Writing --HasSubevent--> Expand <--Synonym--> Spread <--IsA-- Invasion 