Ill is a synonym of Trouble. Devil is a type of Trouble. Devil is related to Vacuum. Vacuum is a different concept from Air. 
Technique is related to Experiment. Experiment is related to Trial. 
Ill <--Synonym--> Trouble <--IsA-- Devil <--RelatedTo--> Vacuum <--DistinctFrom--> Air 
Technique <--RelatedTo--> Experiment <--RelatedTo--> Trial 