A degree of homology between sequences is {HEAD ~ a function} of {TAIL ~ the number} of matching or homologous positions shared by the sequences 
of
A degree of homology between sequences is { HEAD ~ a function } of { TAIL ~ the number } of matching or homologous positions shared by the sequences
OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH