11-731 Machine Translation: Homework 3 - Questions and Clarifications

Question

In Part (iv), when calculating the percentage of words not-aligned, do we count the NULL word?

Answer No, you should not consider NULL word as an unaligned word.

Question

Would you please explain in more detail what is expected for part (v)?

Answer You are asked to count how many words (i.e. word tokens) are aligned to 0,1,2,.... words. And then plot a graph of fertility against the frequency. Unaligned words have the fertility value 0. Although NULL word has its own fertility distribution, for this exercise, you can consider it as a regular word.