{"type":"ScholarlyArticle","title":"Theory of Alignment Generators and Applications to Statistical Machine Translation","authors":[{"name":"Raghavendra Udupa","slug":"raghavendra-udupa","given":"Raghavendra","family":"Udupa","affiliation":"IBM India Research Laboratory , New Delhi"},{"name":"Hemanta Kumar Maji","slug":"hemanta-kumar-maji","given":"Hemanta Kumar","family":"Maji","affiliation":"IBM India Research Laboratory , New Delhi"}],"abstract":"Viterbi Alignment and Decoding are two fundamental search problems in Statistical Machine Translation. Both the problems are known to be NPhard and therefore, it is unlikely that there exists an optimal polynomial time algorithm for either of these search problems. In this paper we characterize exponentially large subspaces in the solution space of Viterbi Alignment and Decoding. Each of these subspaces admits polynomial time optimal search algorithms. We propose a local search heuristic using a neighbourhood relation on these subspaces. Experimental results show that our algorithms produce better solutions taking substantially less time than the previously known algorithms for these problems.","doi":null,"url":"https://ijcai.org/proceedings/2005/156","pdf":"https://ijcai.org/proceedings/2005/0156.pdf","markdown":"https://ijcai.org/proceedings/2005/156.md","bibtex":"https://ijcai.org/proceedings/2005/bibtex/156","volume":{"slug":"2005","title":"Proceedings of the Nineteenth International Joint Conference on Artificial Intelligence","short_title":"IJCAI 2005","url":"https://ijcai.org/proceedings/2005/","year":2005,"location":"Edinburgh, Scotland, UK","dates":"","editors":"","isbn":"","publisher":"International Joint Conferences on Artificial Intelligence","doi_prefix":""},"section":null,"track":"","number":156,"pages":{"first":1142,"last":1146},"keywords":[],"videos":[],"references":[{"position":1,"raw":"[Al-Onaizan et al., 1999] Y. Al-Onaizan, J. Curin, M. Jahr, K. Knight, J. Lafferty, D. Melamed, F. Och, D. Purdy, N. 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