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CSCI544: Homework Assignment №4
Due on Nov 09, 2021 (before class)
Introduction
This assignment gives you hands-on experience on building deep learning
models on named entity recognition (NER). We will use the CoNLL-2003
corpus to build a neural network for NER. The same as HW3, in the folder
named data, there are three files: train, dev and test. In the files of train and
dev, we provide you with the sentences with human-annotated NER tags.
In the file of test, we provide only the raw sentences. The data format is
that, each line contains three items separated by a white space symbol. The
first item is the index of the word in the sentence. The second item is the
word type and the third item is the corresponding NER tag. There will be a
blank line at the end of one sentence. We also provide you with a file named
glove.6B.100d.gz, which is the GloVe word embeddings [1].
We also provide the official evaluation script conll03eval to evaluate the
results of the model. To use the script, you need to install perl and prepare
your prediction file in the following format:
idx word gold pred (1)
where there is a white space between two columns. gold is the gold-standard
NER tag and pred is the model-predicted tag. Then execute the command
line:
perl conll03eval < {predicted file}
where {predicted file} is the prediction file in the prepared format.
1
Task 1: Simple Bidirectional LSTM model (40
points)
The first task is to build a simple bidirectional LSTM model (see slides page
43 in lecture 12 for the network architecture) for NER.
Task. Implementing the bidirectional LSTM network with PyTorch. The
architecture of the network is:
Embedding→ BLSTM→ Linear→ ELU→ classifier
The hyper-parameters of the network are listed in the following table:
embedding dim 100
number of LSTM layers 1
LSTM hidden dim 256
LSTM Dropout 0.33
Linear output dim 128
Train this simple BLSTMmodel with the training data on NER with SGD
as the optimizer. Please tune other parameters that are not specified in the
above table, such as batch size, learning rate and learning rate scheduling.
What are the precision, recall and F1 score on the dev data? (hint: the
reasonable F1 score on dev is 77%.
Task 2: Using GloVe word embeddings (60
points)
The second task is to use the GloVe word embeddings to improve the BLSTM
in Task 1. The way we use the GloVe word embeddings is straight forward:
we initialize the embeddings in our neural network with the corresponding
vectors in GloVe. Note that GloVe is case-insensitive, but our NER model
should be case-sensitive because capitalization is an important information
for NER. You are asked to find a way to deal with this conflict. What are
the precision, recall and F1 score on the dev data? (hint: the reasonable F1
score on dev is 88%.
2
Bonus: LSTM-CNN model (10 points)
The bonus task is to equip the BLSTM model in Task 2 with a CNN module
to capture character-level information (see slides page 45 in lecture 12 for the
network architecture). The character embedding dimension is set to 30. You
need to tune other hyper-parameters of CNN module, such as the number of
CNN layers, the kernel size and output dimension of each CNN layer. What
are the precision, recall and F1 score on the dev data? Predicting the NER
tags of the sentences in the test data and output the predictions in a file
named pred, in the same format of training data. (hint: the bonus points are
assigned based on the ranking of your model F1 score on the test data).
Submission
Please follow the instructions and submit a zipped folder containing:
- A model file named blstm1.pt for the trained model in Task 1.
- A model file named blstm2.pt for the trained model in Task 2.
- Predictions of both dev and test data from Task 1 and Task 2. Name
the file with dev1.out, dev2.out, test1.out and test2.out, respectively.
All these files should be in the same format of training data.
