Extracting Synchronous Grammar Rules From Word-Level Alignments in Linear Time
Hao Zhang and Daniel Gildea and David Chiang
Coling 2008

Input file format:

Two integers specifying the dimensions of alignment grid,
followed by one line per word, each line containing the sequence
of word positions in other language to which this word aligns.

See example input file test.in, example output file test.out.gold.