Parameterized Duplications...
Use A=(prev(Sr))r to find left matches
S=xbxzbzzyby
Sr=ybyzzbzxbx
prev(Sr)=0b201b20b2 A=(prev(Sr))r=2b02b102b0
Only matches with appropriate values in A can be left-extended:
if Si...Si+k matches Sj….Sj+k,
Ai-1=Aj-1 means that we have a match