Cooperative is a type of Organization. Organization is related to Executive. Mayor is a type of Executive. Mayor can be used for Council. 
Grass is related to Tiny. Tiny is a synonym of Slight. Slight is the opposite of Significant. 
Cooperative --IsA--> Organization <--RelatedTo--> Executive <--IsA-- Mayor --UsedFor--> Council 
Grass <--RelatedTo--> Tiny <--Synonym--> Slight <--Antonym--> Significant 