For example, T i -Dep==T j -Dep means T i -Dep being the same as T j -Dep or equivalent (e.g., subj and obj in R3 2 ).
we employ R1 i to extract targets (t) using opinion words (O), R2 i to extract opinion words (o) using targets (T), R3 i to extract targets (t) using extracted targets (T i ) and R4 i to extract opinion words (o) using known opinion words (O i ).