# 讀書筆記: stanford cs 224n
# stanford cs 224n: assignment #4

## Q2
Analyzing NMT Systems (30 points)
(a) (12 points) Here we present a series of errors we found in the outputs of our NMT model (which
is the same as the one you just trained). For each example of a Spanish source sentence, reference
(i.e., ‘gold’) English translation, and NMT (i.e., ‘model’) English translation, please:
CS 224n Assignment 4 Page 5 of 7
**1.Identify the error in the NMT translation.
2.Provide a reason why the model may have made the error (either due to a specific linguistic
construct or specific model limitations).
3.Describe one possible way we might alter the NMT system to fix the observed error.**
Below are the translations that you should analyze as described above. Note that out-of-vocabulary
words are underlined.

1. **(2 points) Source Sentence: Aqu´ı otro de mis favoritos, “La noche estrellada”.**
Reference Translation: So another one of my favorites, “The Starry Night”.
NMT Translation: Here’s another favorite of my favorites, “The Starry Night”.
#### ANS:
error: 重複字（favorite of my favorite）
reason: RNN常出現，可能把one不知道要指向誰
possible solution:在training或是decoding的時候對重複字加入penalty?

1. **(2 points) Source Sentence: Ustedes saben que lo que yo hago es escribir para los ni˜nos, y,de hecho, probablemente soy el autor para ni˜nos, ms ledo en los EEUU.**
Reference Translation: You know, what I do is write for children, and I’m probably America’s
most widely read children’s author, in fact.
NMT Translation: You know what I do is write for children, and in fact, I’m probably the author for children, more reading in the U.S.
#### ANS:
error: 語序不順
reason:對long-term dependencies無法處理？
possible solution:

3. **(2 points) Source Sentence: Un amigo me hizo eso – Richard Bolingbroke.**
Reference Translation: A friend of mine did that – Richard Bolingbroke.
NMT Translation: A friend of mine did that – Richard <unk>

#### ANS:
error:<unk>
reason: 遇到特殊字？人名？
possible solution: 加入training或是學習對特殊字做處理

4. **(2 points) Source Sentence: Solo tienes que dar vuelta a la manzana para verlo como unaepifan´ıa.**
Reference Translation: You’ve just got to go around the block to see it as an epiphany.
NMT Translation: You just have to go back to the apple to see it as a epiphany.
#### ANS:
error: manzana有兩種意思
reason: 選了出現頻率高的？
possible solution:Word Sense Disambiguation (WSD) ??

1. **(2 points) Source Sentence: Ella salv´o mi vida al permitirme entrar al ba˜no de la sala de profesores.**
Reference Translation: She saved my life by letting me go to the bathroom in the teachers’ lounge.
NMT Translation: She saved my life by letting me go to the bathroom in the women’s room.
#### ANS:
error:profesor == women!
reason:profesore大多是女性，故產生bias
possible solution:

1. **(2 points) Source Sentence: Eso es m´as de 100,000 hect´areas.**
Reference Translation: That’s more than 250 thousand acres.
NMT Translation: That’s over 100,000 acres.
#### ANS:
error: 數字一樣單位不同？？
reason:沒看過hectareas
possible solution: 確定hectareas在訓練及，或是將單位的概念放在訓練及中