Lower is a type of Change. Change is related to Slope. Slope is related to Decent. 
Battle is related to Fight. Fight is related to Activity. Fun is a type of Activity. Survival can be Fun. 
Lower --IsA--> Change <--RelatedTo--> Slope <--RelatedTo--> Decent 
Battle <--RelatedTo--> Fight <--RelatedTo--> Activity <--IsA-- Fun <--HasProperty-- Survival 