1. A method for performing bilingual word alignment, as characterized, comprising: preprocessing source and target texts of bilingual documents to be aligned; computing probability gains of adding a link between any pair of source and target words; setting the initial word alignment as an empty alignment; applying a greedy algorithm to iteratively search for word alignments that satisfy an inversion transduction grammar constraint; and outputting a best word alignment among the alignments that satisfy the inversion transduction grammar constraint as a final alignment result.