{HEAD ~ Optimal alignments} in {TAIL ~ linear space}, CABIOS 4:1, 11 17; Chao, K M, W. R. Pearson and W. Miller 
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{ HEAD ~ Optimal alignments } in { TAIL ~ linear space } , CABIOS 4:1 , 11 17 ; Chao , K M , W. R. Pearson and W. Miller
HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH