Graph constructing process. (A) Step 1-Structural skeleton construction: Adding a new base-pair (x
, xi′) and aligning that with its best match: (y
, yj′). (B-D) Step 2-Inserting highly probable local alignments: (B) Adding a new column (node) c*. (C) Extending an existing column (node) c. (D) Merging two columns (nodes) c1 and c2 into a single column (node) c*.