Therefore, when {HEAD ~ a given symbol} of {TAIL ~ interest} is considered, the other symbols of interest may be considered as interfering symbols 
of
Therefore , when { HEAD ~ a given symbol } of { TAIL ~ interest } is considered , the other symbols of interest may be considered as interfering symbols
OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH