Challenges of Machine Translation CSC 4598 Machine Translation Dr. Tom Way
Translation is hard Novels Word play, jokes, puns, hidden messages Concept gaps: go Greek, bei fen Other constraints: lyrics, dubbing, poem, …
Major challenges Getting the right words: Choosing the correct root form Getting the correct inflected form Inserting “spontaneous” words Putting the words in the correct order: Word order: SVO vs. SOV, … Unique constructions: Divergence
Lexical choice Homonymy/Polysemy: bank, run Concept gap: no corresponding concepts in another language: go Greek, go Dutch, fen sui, lame duck, … Coding (Concept lexeme mapping) differences: More distinction in one language: e.g., kinship vocabulary. Different division of conceptual space:
Choosing the appropriate inflection Inflection: gender, number, case, tense, … Ex: Number: Ch-Eng: all the concrete nouns: ch_book book, books Gender: Eng-Fr: all the adjectives Case: Eng-Korean: all the arguments Tense: Ch-Eng: all the verbs: ch_buy buy, bought, will buy
Inserting spontaneous words Function words: Determiners: Ch-Eng: ch_book a book, the book, the books, books Prepositions: Ch-Eng: … ch_November … in November Relative pronouns: Ch-Eng: … ch_buy ch_book de ch_person the person who bought /book/ Possessive pronouns: Ch-Eng: ch_he ch_raise ch_hand He raised his hand(s) Conjunction: Eng-Ch: Although S1, S2 ch_although S1, ch_but S2 …
Inserting spontaneous words (cont) Content words: Dropped argument: Ch-Eng: ch_buy le ma Has Subj bought Obj? Chinese First name: Eng-Ch: Jiang … ch_Jiang ch_Zemin … Abbreviation, Acronyms: Ch-Eng: ch_12 ch_big the 12th National Congress of the CPC (Communist Party of China) …
Major challenges Putting the words in the correct order: Getting the right words: Choosing the correct root form Getting the correct inflected form Inserting “spontaneous” words Putting the words in the correct order: Word order: SVO vs. SOV, … Unique construction: Structural divergence
Word order SVO, SOV, VSO, … VP + PP PP VP VP + AdvP AdvP + VP Adj + N N + Adj NP + PP PP NP NP + S S NP P + NP NP + P
“Unique” Constructions Overt wh-movement: Eng-Ch: Eng: Why do you think that he came yesterday? Ch: you why think he yesterday come ASP? Ch: you think he yesterday why come? Ba-construction: Ch-Eng She ba homework finish ASP She finished her homework. He ba wall dig ASP CL hole He digged a hole in the wall. She ba orange peel ASP skin She peeled the orange’s skin.
Translation divergences Source and target parse trees (dependency trees) are not identical. Example: I like Mary S: Marta me gusta a mi (‘Mary pleases me’)