Issue is related to World. World can be Blue. Blue is a different concept from Purple. 
Observe is related to Study. Study is a synonym of Research. Museum can be used for Research. you are likely to find Tour in/at/on Museum. 
Issue <--RelatedTo--> World --HasProperty--> Blue <--DistinctFrom--> Purple 
Observe <--RelatedTo--> Study <--Synonym--> Research <--UsedFor-- Museum <--AtLocation-- Tour 