Sentence:  <WSD>Hence</WSD> , when the address * * f is computed from * * f , the cell * * f and all Y-cells in its chain must be inspected to determine whether * * f is already in the form list or whether it should be added to the form list and the chain . 
Meaning of the word marked with <WSD> tags:  (used to introduce a logical conclusion) from that fact or reason or as a result