Fundamental is related to Theory. Theory is related to Opinion. Opinion is related to Agree. 
Topic is related to Subject. Subject is related to Camera. Camera is related to Equipment. Equipment is related to Machine. 
Fundamental <--RelatedTo--> Theory <--RelatedTo--> Opinion <--RelatedTo--> Agree 
Topic <--RelatedTo--> Subject <--RelatedTo--> Camera <--RelatedTo--> Equipment <--RelatedTo--> Machine 