For Wednesday• No reading• Homework

– Chapter 23, exercise 15– Process:

1. Create 5 sentences

2. Select a language

3. Translate each sentence into that language and back to English – look at the result

4. Translate the results into the other language and back to English again

5. Pick a different language and repeat steps 3 and 4

6. Discuss

– I want to see all of the English sentences and the discussion. You do not have to do the last part even if you do know another language.

Program 5

• Any questions?

Machine Translation

• Best systems must use all levels of NLP• Semantics must deal with the overlapping

senses of different languages• Both understanding and generation• Advantage in learning: bilingual corpora

exist--but we often want some tagging of intermediate relationships

• Additional issue: alignment of corpora

Approaches to MT

• Lots of hand-built systems• Some learning used• Probably most use a fair bit of syntactic and

semantic analysis• Some operate fairly directly between texts

Generation

• Producing a syntactically “good” sentence• Interesting issues are largely in choices

– What vocabulary to use– What level of detail is appropriate– Determining how much information to include

Ethical issues in AI

• What are the benefits and risks in attempting to develop AI programs?