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<article xmlns:xlink="http://www.w3.org/1999/xlink">
  <front>
    <journal-meta />
    <article-meta>
      <title-group>
        <article-title>Leveraging Domain Agnostic and Specific Knowledge for Acronym Disambiguation</article-title>
      </title-group>
      <contrib-group>
        <contrib contrib-type="author">
          <string-name>Qiwei Zhong</string-name>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Guanxiong Zeng</string-name>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Danqing Zhu</string-name>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Yang Zhang</string-name>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Wangli Lin</string-name>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Ben Chen</string-name>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Jiayu Tang</string-name>
          <email>jiayu.tangjyg@alibaba-inc.com</email>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <aff id="aff0">
          <label>0</label>
          <institution>Alibaba Group</institution>
          ,
          <addr-line>Hangzhou</addr-line>
          ,
          <country country="CN">China</country>
        </aff>
      </contrib-group>
      <abstract>
        <p>An obstacle to scientific document understanding is the extensive use of acronyms which are shortened forms of long technical phrases. Acronym disambiguation aims to find the correct meaning of an ambiguous acronym in a given text. Recent efforts attempted to incorporate word embeddings and deep learning architectures, and achieved significant effects in this task. In general domains, kinds of fine-grained pretrained language models have sprung up, thanks to the largescale corpora which can usually be obtained through crowdsourcing. However, these models based on domain agnostic knowledge might achieve insufficient performance when directly applied to the scientific domain. Moreover, obtaining large-scale high-quality annotated data and representing high-level semantics in the scientific domain is challenging and expensive. In this paper, we consider both the domain agnostic and specific knowledge, and propose a Hierarchical Dual-path BERT method coined hdBERT to capture the general fine-grained and high-level specific representations for acronym disambiguation. First, the context-based pretrained models, RoBERTa and SciBERT, are elaborately involved in encoding these two kinds of knowledge respectively. Second, multiple layer perceptron is devised to integrate the dualpath representations simultaneously and outputs the prediction. With a widely adopted SciAD dataset contained 62,441 sentences, we investigate the effectiveness of hdBERT. The experimental results exhibit that the proposed approach outperforms state-of-the-art methods among various evaluation metrics. Specifically, its macro F1 achieves 93.73%.</p>
      </abstract>
    </article-meta>
  </front>
  <body>
    <sec id="sec-1">
      <title>Introduction</title>
      <p>
        In recent years, it has witnessed the vigorous development
of deep learning. Among the most successful scenarios,
natural language processing (NLP) is advancing steadily.
However, natural language is frequently ambiguous, so many
words and phrases can be interpreted in many ways
depending on the context in which they appear
        <xref ref-type="bibr" rid="ref20">(Navigli 2009)</xref>
        .
Specifically, an obstacle to scientific document
understanding (SDU) is the widespread use of acronyms, which are
shortened forms of long technical phrases
        <xref ref-type="bibr" rid="ref25 ref28 ref29 ref4">(Veyseh et al.
2020b; Beltagy, Lo, and Cohan 2019)</xref>
        . In order to understand
the document correctly, the SDU system should be able to
Copyright © 2021 for this paper by its authors. Use permitted under
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identify acronyms and their correct meanings. The goal of
acronym disambiguation (AD) is to determine the correct
long form of an ambiguous acronym in a given text
        <xref ref-type="bibr" rid="ref28 ref29">(Veyseh
et al. 2020a)</xref>
        . It is usually formulated as a sequence
classification problem in general
        <xref ref-type="bibr" rid="ref25 ref28 ref29">(Veyseh et al. 2020b)</xref>
        . For
instance, a toy sample of this task is shown in Table 1. In this
example, the “CNN” might be an acronym for
“Convolutional Neural Network”, “Cable News Network” or
“Condensed Nearest Neighbor”. Given a sentence “They use
CNN in the proposed model.” and a dictionary with
possible expansions (i.e., long forms) of the acronym “CNN”,
the expected prediction for its correct meaning is
“Convolutional Neural Network”. Recent efforts attempted to
incorporate hand crafted features
        <xref ref-type="bibr" rid="ref17">(Li et al. 2018)</xref>
        , word
embeddings
        <xref ref-type="bibr" rid="ref7 ref9">(Charbonnier and Wartena 2018; Ciosici,
Sommer, and Assent 2019)</xref>
        , graph structures
        <xref ref-type="bibr" rid="ref24 ref25 ref28 ref29">(Prokofyev et al.
2013; Veyseh et al. 2020b)</xref>
        , and deep learning
architectures
        <xref ref-type="bibr" rid="ref14 ref5 ref6">(Jin, Liu, and Lu 2019; Blevins and Zettlemoyer 2020)</xref>
        and achieved significant effects in this task.
      </p>
      <p>
        In this paper, we pay more attention to the scenario of
scientific acronym disambiguation. Some observations are still
worthy of further investigation. Generally, large-scale
training data for natural language processing tasks in general
domains is often possible to obtain through crowd-sourcing,
emerging a variety of domain-independent fine-grained
pretrained models. However, these models based on domain
agnostic knowledge might achieve insufficient performance
when applied to the specific domain
        <xref ref-type="bibr" rid="ref4">(Beltagy, Lo, and Cohan
2019)</xref>
        . Furthermore, obtaining large-scale annotated data in
the scientific domain is challenging and expensive
        <xref ref-type="bibr" rid="ref4">(Beltagy,
Lo, and Cohan 2019)</xref>
        , which leads to the shortage of
highlevel semantic expression to some extent.
      </p>
      <p>
        To remedy these challenges, we fully consider both the
domain agnostic and specific knowledge, and propose a
Hierarchical Dual-path BERT method coined hdBERT to
fusion the general fine-grained and high-level specific
representations for acronym disambiguation. The overall
architecture is illustrated in Figure 1. We pinpoint that
hdBERT is a BERT-based supervised method adopting the now
ubiquitous transformer architecture
        <xref ref-type="bibr" rid="ref27">(Vaswani et al. 2017)</xref>
        .
First, RoBERTa
        <xref ref-type="bibr" rid="ref14">(Liu et al. 2019)</xref>
        and SciBERT
        <xref ref-type="bibr" rid="ref4">(Beltagy, Lo,
and Cohan 2019)</xref>
        modules are elaborately involved to
distill representations from inputs consist of sentence and
candidate long forms. Specifically, we utilize RoBERTa, a
robustly optimized method trained on general domain corpora
via byte-level Byte-Pair-Encoding
        <xref ref-type="bibr" rid="ref26">(Sennrich, Haddow, and
Birch 2016)</xref>
        , to capture domain agnostic and fine-grained
semantic information. Moreover, SciBERT which is also a
pretrained language model based on BERT
        <xref ref-type="bibr" rid="ref10">(Devlin et al. 2019)</xref>
        is exploited to model the high-level scientific domain
representation. Since it leverages unsupervised pretraining on
a large multi-domain corpus of scientific publications using
WordPiece
        <xref ref-type="bibr" rid="ref32">(Wu et al. 2016)</xref>
        tokenization strategy. Second,
we integrate these dual-path representations from RoBERTa
and SciBERT simultaneously via multiple layer perceptron
and output the prediction. The main contributions of this
work are summarized as follows:
• We are the very first attempt to resolve the acronym
disambiguation problem simultaneously leveraging domain
agnostic and specific knowledge.
• We propose a novel hierarchical dual-path BERT method
coined hdBERT to capture both general fine-grained and
high-level specific representations. It is mainly
implemented based on the well-known transformer
architecture, which can train the overall model more effectively.
• Experiments on real-world datasets demonstrate the
effectiveness of the proposed approach. It achieves competitive
performance and outperforms state-of-the-art methods.
      </p>
    </sec>
    <sec id="sec-2">
      <title>Related Work</title>
      <p>In this section, we review the related researches on word
sense disambiguation especially acronym disambiguation as
well as BERT and its two representative variants.</p>
      <sec id="sec-2-1">
        <title>Word Sense Disambiguation</title>
        <p>
          Word sense disambiguation (WSD) is an open problem
concerned with identifying which sense of a word is used in
a text
          <xref ref-type="bibr" rid="ref20">(Navigli 2009)</xref>
          . It is a core and difficulty in
natural language processing tasks, which affects the
performance of almost all downstream tasks. The methods to solve
word sense disambiguation are usually divided into two
categories: knowledge-based and supervised
          <xref ref-type="bibr" rid="ref3 ref30 ref5 ref6">(Wang, Wang, and
Fujita 2020; Barba et al. 2020)</xref>
          .
        </p>
        <p>
          Knowledge-based methods usually rely on amounts of
statistical information and can be easily extended to other
low-resource languages
          <xref ref-type="bibr" rid="ref1 ref25 ref5 ref6">(Agirre, Lo´pez de Lacalle, and
Soroa 2014; Scarlini, Pasini, and Navigli 2020)</xref>
          . For
example, SensEmBERT
          <xref ref-type="bibr" rid="ref25 ref5 ref6">(Scarlini, Pasini, and Navigli 2020)</xref>
          , a
knowledge- and BERT-based method that combines the
expressive power of language modeling with the vast amount
of knowledge contained in the semantic network, produces
high-quality latent semantic representations of the
meanings of the word in different languages. And it can achieve
competitive results attained by most of the supervised
neural approaches on the WSD tasks. On the other hand,
supervised methods require lots of labeled data to learn word
representations
          <xref ref-type="bibr" rid="ref30 ref5 ref5 ref6 ref6">(Bevilacqua and Navigli 2020; Wang, Wang,
and Fujita 2020)</xref>
          . Of course, this defect can be alleviated
through semi-supervised methods
          <xref ref-type="bibr" rid="ref3">(Barba et al. 2020)</xref>
          by
jointly leveraging contextualized word embedding and the
multilingual information to project some sense labels.
        </p>
        <p>
          Furthermore, acronym disambiguation is more
challenging since we need to identify the acronym first and then
to understand the text to determine the correct meaning
of acronyms. Recently, an effective solution is to extract
acronym definitions from unstructured texts by computing
the Levenshtein string edit distance between any pair of
long forms
          <xref ref-type="bibr" rid="ref9">(Ciosici, Sommer, and Assent 2019)</xref>
          , which is
an entirely unsupervised acronym disambiguation method.
And researches also attempt to incorporate hand crafted
features
          <xref ref-type="bibr" rid="ref17">(Li et al. 2018)</xref>
          , word embeddings
          <xref ref-type="bibr" rid="ref7 ref9">(Charbonnier and
Wartena 2018; Ciosici, Sommer, and Assent 2019)</xref>
          , graph
structures
          <xref ref-type="bibr" rid="ref24 ref25 ref28 ref29">(Prokofyev et al. 2013; Veyseh et al. 2020b)</xref>
          , and
deep learning architectures
          <xref ref-type="bibr" rid="ref14 ref5 ref6">(Jin, Liu, and Lu 2019; Blevins
and Zettlemoyer 2020)</xref>
          , and have achieved significant
effects in this task. Specifically, a supervised method named
GAD
          <xref ref-type="bibr" rid="ref25 ref28 ref29">(Veyseh et al. 2020b)</xref>
          , which utilizes the syntactic
structure of sentences to extend ambiguous acronyms in
sentences by combining Bidirectional Long Short-Term
Memory (BiLSTM) with Graph Convolutional Networks (GCN),
provides a strong baseline on acronym disambiguation tasks
in the scientific domain.
        </p>
      </sec>
      <sec id="sec-2-2">
        <title>BERT-based Methods</title>
        <p>
          Bidirectional Encoder Representations from Transformers
(BERT)
          <xref ref-type="bibr" rid="ref10">(Devlin et al. 2019)</xref>
          is a self-supervised learning
method that trains based on a large number of corpora to
express better features for word embedding. And its
network architecture utilizes the multi-layer transformer
structure
          <xref ref-type="bibr" rid="ref27">(Vaswani et al. 2017)</xref>
          . The feature representation of
BERT could be directly adopted as word embedding features
for downstream tasks. Besides, BERT provides a model for
transfer learning of other tasks. It can be fine-tuned or fixed
according to tasks and then treated as a feature extractor.
BERT was significantly undertrained, and there have been
many fine-grained improvements or specific domain variants
of it
          <xref ref-type="bibr" rid="ref14 ref15 ref25 ref4 ref5 ref6">(Beltagy, Lo, and Cohan 2019; Liu et al. 2019; Scarlini,
Pasini, and Navigli 2020; Lee et al. 2020)</xref>
          .
        </p>
        <p>
          RoBERTa. RoBERTa
          <xref ref-type="bibr" rid="ref14">(Liu et al. 2019)</xref>
          is mainly trained
on general domain corpora via byte-level
Byte-PairEncoding
          <xref ref-type="bibr" rid="ref26">(Sennrich, Haddow, and Birch 2016)</xref>
          based on the
structure of BERT and can supply more fine-grained
representation. This encoding scheme can process amounts of
words that are common in natural language corpora and is
        </p>
        <p>
          SciBERT. SciBERT
          <xref ref-type="bibr" rid="ref4">(Beltagy, Lo, and Cohan 2019)</xref>
          is a
specific pretrained language model for scientific domain
texts. This model follows the same architecture as BERT
to solve the lack of high-quality, large-scale labeled
scientific data. It significantly outperforms previous BERT-based
methods and achieves new state-of-the-art results on some
scientific NLP tasks.
        </p>
      </sec>
    </sec>
    <sec id="sec-3">
      <title>Methodology</title>
      <p>In this section, we first introduce the problem statement of
acronym disambiguation and then describe the overall
architecture and details of our proposed hdBERT model.</p>
      <sec id="sec-3-1">
        <title>Problem Statement</title>
        <p>
          Acronym disambiguation is formulated as a sequence
classification problem in general
          <xref ref-type="bibr" rid="ref25 ref28 ref29">(Veyseh et al. 2020b)</xref>
          . Formally,
given an input sentence s = w1; w2; :::; wn and the
position of the acronym, i.e., p, the goal is to disambiguate the
acronym wp, that is, predicting the true long form l from all
candidate long forms of wp. Specifically, in this paper, we
simplify it into a binary classification problem. That is, given
an input sample consists of the sentence s with acronym wp
and the candidate long form l, i.e., x = (s; l), our purpose
is to predict the probability of l being the right long form of
wp. We assign a label y 2 f0; 1g on each sample in
training dataset to indicate whether l is a true long form of wp in
sentence s or not. In the testing phase, the long form with
the highest prediction probability among the candidate long
form set of a sentence would be chosen as its final result.
        </p>
      </sec>
      <sec id="sec-3-2">
        <title>Overview</title>
        <p>
          Figure 1 exhibits the schematic illustration of the proposed
hdBERT model. As mentioned previously, we design a
hierarchical integration model comprising three major
components, each plays a different role in final prediction. The first
two context-based components, i.e., RoBERTa
          <xref ref-type="bibr" rid="ref14">(Liu et al.
2019)</xref>
          and SciBERT
          <xref ref-type="bibr" rid="ref4">(Beltagy, Lo, and Cohan 2019)</xref>
          modules, distill representations of the sentence and the candidate
long forms. Specifically, as a robustly optimized method
trained on vast amounts of general domain corpora, we use
RoBERTa to capture the general and fine-grained semantic
information via byte-level Byte-Pair-Encoding
          <xref ref-type="bibr" rid="ref26">(Sennrich,
Haddow, and Birch 2016)</xref>
          . Moreover, SciBERT, which
leverages unsupervised pretraining on a large scientific corpus
by WordPiece
          <xref ref-type="bibr" rid="ref32">(Wu et al. 2016)</xref>
          tokenization strategy, is
exploited to represent the high-level scientific domain
information. Finally, a multiple layer perceptron network is devised
to fusion these two kinds of representations. In the
following, we present detail of each major component.
        </p>
      </sec>
      <sec id="sec-3-3">
        <title>Information Distillation</title>
      </sec>
      <sec id="sec-3-4">
        <title>General and Fine-grained Information. We involve</title>
        <p>
          RoBERTa to capture domain agnostic and fine-grained
information of the sentence and its candidate long form.
RoBERTa uses the now ubiquitous transformer
architecture
          <xref ref-type="bibr" rid="ref27">(Vaswani et al. 2017)</xref>
          via byte-level Byte-Pair-Encoding
(BPE), which is a hybrid between character- and word-level
representations that allow handling large vocabularies
common in natural language corpora. Instead of full words, BPE
relies on subwords units, which are extracted by
performing statistical analysis of the training corpus. The size of the
original vocabulary released with RoBERTa is about 50K,
which is 20K more than BERT’s.
        </p>
        <p>We define the encoding of a sample x = (s; l) after the
BPE strategy as eBPE and the output representation
throughout the RoBERTa model as hRoBERTa.</p>
        <p>eBPE = BPE(x)
hRoBERTa = RoBERTa(eBPE)
(1)
(2)</p>
      </sec>
      <sec id="sec-3-5">
        <title>High-level Scientific Domain Information. To handle</title>
        <p>
          the high-level scientific domain information, SciBERT is
chosen elaborately. SciBERT follows the same architecture
Statistical Information
number of acronyms
average number of long form per acronym
overlap between sentence and long forms
average sentence length
number of training
number of development
number of test
as BERT but is instead pretrained on the scientific texts. It
constructed a new WordPiece vocabulary on scientific
corpus using the SentencePiece library and trained on a
random sample of 1.14M papers from Semantic Scholar
          <xref ref-type="bibr" rid="ref2">(Ammar et al. 2018)</xref>
          . Its corpus consists of 18% papers from the
computer science domain and 82% from the broad
biomedical domain. The size of the original vocabulary released with
SciBERT is about 30K, which is 20K less than RoBERTa.
The resulting token overlap between SciBERT and BERT is
42%, which illustrates the significant difference in common
terms between scientific and general domain texts.
        </p>
        <p>We define the encoding of a sample x = (s; l) after
SciBERT’s encoding strategy (noted as WPE) as eWPE and
the output representation throughout the SciBERT model as
hSciBERT.</p>
        <p>Integration</p>
        <p>eWPE = WPE(x)
hSciBERT = SciBERT(eWPE)
(3)
(4)
(5)
(6)
After modeling the two complex representations above, the
obtained concatenation h is fed into multiple layer
perceptron network and followed by a regression layer with
sigmoid unit, as follows:</p>
        <p>h = [hRoBERTa; hSciBERT]
p = sigmoid(W TMLP(h) + b)</p>
        <p>D
where W is the weight vector, b is the bias, and MLP( )
represents the operation of multiple layer perceptron shown
in Figure 1. Here p is the predicted probability.</p>
        <p>Finally, our model is trained with cross entropy loss with
regularization. The loss function is defined as</p>
        <p>L( ) =</p>
        <p>X (y log(p) + (1
y) log(1
p)) +</p>
        <p>2
k k2
(7)
where y is the ground truth, is the parameter set of the
proposed model, is the regularizer parameter, and D is the
training dataset.</p>
      </sec>
    </sec>
    <sec id="sec-4">
      <title>Experiments</title>
      <p>
        In this section, we first illustrate the datasets, evaluation
metrics, and implementation details, then demonstrate the
experimental results and further studies.
The SciAD 1 dataset created from 6,786 English scientific
papers aims to find the correct meaning of an ambiguous
acronym in a given sentence
        <xref ref-type="bibr" rid="ref25 ref28 ref29">(Veyseh et al. 2020b)</xref>
        . It
contains 62,441 sentences and a dictionary of 732 ambiguous
acronyms. More statistical information is shown in Table 2.
Besides, a toy sample of the SciAD dataset is shown in
Table 1. The input is a sentence with an ambiguous acronym
and a dictionary with possible expansions (i.e., long forms)
of the acronym. In this example, the ambiguous acronym
“CNN” in the input sentence is shown in boldface and the
expected prediction for its correct meaning is “Convolutional
Neural Network”. In addition, Figures 2 and 3 demonstrate
more statistics of SciAD dataset
        <xref ref-type="bibr" rid="ref25 ref28 ref29">(Veyseh et al. 2020b)</xref>
        . More
specifically, Figure 2 shows the distribution of the number of
acronyms based on the number of long forms per acronym,
and the distribution of the number of samples based on the
number of long form per acronym is shown in Figure 3.
      </p>
      <p>As mentioned previously, we convert the original SciAD
dataset into a binary classification dataset named SciADBI
during modeling. For a sentence s with acronym wp, y = 1
1We won second place in the acronym disambiguation
competition. https://sites.google.com/view/sdu-aaai21/shared-task
Parameter
pretrained model
architecture
attention probs dropout prob
hidden act
hidden dropout prob
hidden size
initializer range
intermediate size
layer norm eps
max position embeddings
model type
num attention heads
num hidden layers
position embedding type
vocab size
learning rate
epoch
a https://huggingface.co/bert-large-uncased
b https://huggingface.co/roberta-large
c https://github.com/allenai/scibert
if a long form l is true for wp, while y = 0 for other false
candidate long forms of wp. Specifically, to alleviate the
imbalance problem during training, we upsample each positive
sample to equal the number of candidate long forms of its
acronym. More statistics of SciADBI is shown in Table 4.
We finally evaluate performances on SciAD’s test dataset.</p>
      <sec id="sec-4-1">
        <title>Compared Methods</title>
        <p>We compare with several state-of-the-art and representative
methods including Non-deep learning methods and Deep
learning methods to verify the effectiveness of our proposed
method.</p>
        <p>
          Non-deep learning methods.
• MF: most frequent which takes the long form with the
highest frequency among all possible meanings of an
acronym as the expanded form of the acronym.
• ADE
          <xref ref-type="bibr" rid="ref17">(Li et al. 2018)</xref>
          : a feature-based model that employs
hand crafted features from the context of the acronyms to
train a disambiguation classifier.
        </p>
      </sec>
      <sec id="sec-4-2">
        <title>Deep learning methods.</title>
        <p>
          • NOA
          <xref ref-type="bibr" rid="ref7">(Charbonnier and Wartena 2018)</xref>
          and UAD
          <xref ref-type="bibr" rid="ref9">(Ciosici,
Sommer, and Assent 2019)</xref>
          : language-model-based
baselines that train the word embeddings using the training
corpus.
• DECBAE
          <xref ref-type="bibr" rid="ref14">(Jin, Liu, and Lu 2019)</xref>
          and BEM
          <xref ref-type="bibr" rid="ref5 ref6">(Blevins and
Zettlemoyer 2020)</xref>
          : models employing deep architectures
(e.g., LSTM).
• GAD
          <xref ref-type="bibr" rid="ref25 ref28 ref29">(Veyseh et al. 2020b)</xref>
          : supervised method which
utilizes syntactic structure of sentences to extend ambiguous
acronyms in sentences by combining BiLSTM with GCN.
• BERT
          <xref ref-type="bibr" rid="ref10">(Devlin et al. 2019)</xref>
          , RoBERTa
          <xref ref-type="bibr" rid="ref14">(Liu et al. 2019)</xref>
          and SciBERT
          <xref ref-type="bibr" rid="ref4">(Beltagy, Lo, and Cohan 2019)</xref>
          : pretrained
models use the now ubiquitous transformer architecture.
        </p>
      </sec>
      <sec id="sec-4-3">
        <title>Evaluation Metrics</title>
        <p>To evaluate the performance of different methods, three
popular metrics are adopted, namely Macro Precision, Macro
Recall and Macro F1. The definitions are as follows:
PrecisionMACRO =</p>
        <p>RecallMACRO =</p>
        <p>Pn
i=1 Precisioni</p>
        <p>n
Pn
i=1 Recalli
n
(8)
(9)
F1MACRO =
2</p>
        <sec id="sec-4-3-1">
          <title>PrecisionMACRO</title>
        </sec>
        <sec id="sec-4-3-2">
          <title>RecallMACRO</title>
        </sec>
        <sec id="sec-4-3-3">
          <title>PrecisionMACRO + RecallMACRO</title>
          <p>(10)
where n is the number of total classes, Precisioni and
Recalli represent the precision and recall of class i
respectively. The higher PrecisionMACRO, RecallMACRO and
F1MACRO indicate the higher performance of approaches.</p>
        </sec>
      </sec>
      <sec id="sec-4-4">
        <title>Methodology MF</title>
        <p>
          ADE
          <xref ref-type="bibr" rid="ref17">(Li et al. 2018)</xref>
          NOA
          <xref ref-type="bibr" rid="ref7">(Charbonnier and Wartena 2018)</xref>
          UAD
          <xref ref-type="bibr" rid="ref9">(Ciosici, Sommer, and Assent 2019)</xref>
          BEM
          <xref ref-type="bibr" rid="ref5 ref6">(Blevins and Zettlemoyer 2020)</xref>
          DECBAE
          <xref ref-type="bibr" rid="ref14">(Jin, Liu, and Lu 2019)</xref>
          GAD
          <xref ref-type="bibr" rid="ref25 ref28 ref29">(Veyseh et al. 2020b)</xref>
          Human Performance
          <xref ref-type="bibr" rid="ref25 ref28 ref29">(Veyseh et al. 2020b)</xref>
          MF
BERT
          <xref ref-type="bibr" rid="ref10">(Devlin et al. 2019)</xref>
          RoBERTa
          <xref ref-type="bibr" rid="ref14">(Liu et al. 2019)</xref>
          SciBERT
          <xref ref-type="bibr" rid="ref4">(Beltagy, Lo, and Cohan 2019)</xref>
          hdBERT (ours)
        </p>
      </sec>
      <sec id="sec-4-5">
        <title>Implementation Details</title>
        <p>
          For models ADE, NOA, UAD, DECBAE, BEM, and GAD,
please refer to Veyseh et al. for more implementation
information. We implement the proposed model based on
Pytorch
          <xref ref-type="bibr" rid="ref22">(Paszke et al. 2019)</xref>
          and Transformers
          <xref ref-type="bibr" rid="ref31">(Wolf et al.
2020)</xref>
          . For models BERT, RoBERTa, and SciBERT, we
finetune them on dataset based on their popular pretrained
models. The implementation details of these models are shown
in Table 3. Moreover, the information distillation
components of our model are the same as model RoBERTa and
SciBERT respectively. And we simply adopt three MLP
layers for integration simultaneously. As mentioned previously,
in the testing phase, the long form with the highest
prediction probability in the candidate long form set of a sentence
would be chosen as its final result. In addition, we use two
V100 GPUs with 12 cores to complete all these experiments.
        </p>
      </sec>
      <sec id="sec-4-6">
        <title>Performance Comparison</title>
        <p>Table 5 demonstrates the main results of all compared
methods 2 on the dataset. The major findings from the
experimental results can be summarized as follows:</p>
        <p>First, GAD achieves a better result than methods such as
ADE, NOA, UAD, BEM, and DECBAE, showing the
importance of syntactic structure for the acronym
disambiguation task. But it still far worse than pretraining-based models
like BERT and RoBERTa. Second, between the two
generaldomain models, RoBERTa gets better performance than
BERT, indicating the advantage of more fine-grained
encoding. Moreover, SciBERT is more advanced than the domain
agnostic methods, i.e., BERT and RoBERTa, with about
2.26% and 1.03% increased macro F1 respectively, showing
the importance of the scientific domain pretraining for this
task. Furthermore, we can clearly observe that our hdBERT
model outperforms all the baselines by a large margin. Its
macro F1, with the reported value of 93.73%, is about 1.88%
and 0.84% higher than state-of-the-art RoBERTa and
SciBERT respectively. And its loss curve falls faster and
con2We assume that both Veyseh et al. and this task have the same
distribution of dataset due to the randomly dividing by the same
ratio, making all these methods comparable.
verges lower than the two pretrained methods on the
development dataset, as shown in Figure 4. These observations
demonstrate that it is effective to model both fine-grained
domain agnostic and high-level domain specific knowledge
simultaneously.</p>
        <p>However, despite the significant improvements among
these approaches, performances of all models are still not
as effective as humans on the dataset, especially on macro
recall and macro F1, thus providing many further research
opportunities for this scenario.</p>
      </sec>
      <sec id="sec-4-7">
        <title>Case Study</title>
        <p>We further focus on studying both success and failure cases
of pretraining-based models to provide more insight into
acronym disambiguation. Specifically, for success case of
our model in which RoBERTa and SciBERT fail, e.g., “Each
SP within an SM shares an instruction unit, dedicated to
the management of the instruction flow of the threads.”
(DEV-6156), the true long form of “SM” is “Streaming
Multiprocessors”. While both RoBERTa and SciBERT output
“Shared Memory”, which may often appear in deep learning
publications. It might benefit from the additional integration
modeling of two different information from RoBERTa and
SciBERT. However, all the three models fail in this
examSentence
Just like RF, QRF is a set of binary regression trees.</p>
        <p>Extensions of the SBM regarding the type of graph are reviewed in Section.
The obfuscated term is the term for which the MACS score is the lowest.
Conflicted Annotation
TR-43200: Regression Forest
TR-49535: Regression Function
TR-17276: Sequential Monte Carlo
TR-47761: Stochastic Block Model
TR-15480: Mean Average Conceptual Similarity
TR-27970: Minimum Average Conceptual Similarity
ple: “In the first stage, we train the SPM, and extract the FL
and FR.” (DEV-4604) with the wrong prediction “Federated
Learning” for “FL”. The true long form of “FL” is “Fixated
Locations”. We guess that all models pay too much attention
to “Federated Learning”, a hot phrase nowadays, and ignore
the subtle information among the sentence and its different
candidate long forms. It also indicates the necessity of more
advanced models for this task.</p>
      </sec>
      <sec id="sec-4-8">
        <title>Further Discussion</title>
        <p>
          As mentioned previously and shown in Table 5, all the
current models are still less effective than humans in this
scenario. There are still many samples that all models fail in.
Some further research opportunities on this dataset are
discussed in this section. First, as shown in Table 6, there are
some noise data, i.e., conflicted annotation, in the SciAD
dataset. For example, the acronym “RF” in boldface in
sentence “Just like RF, QRF is a set of binary regression
trees.” gets two different long form “Regression Forest”
(TR-43200) and “Regression Function” (TR-49535)
respectively. It will be some negative impacts on modeling to some
extent. Furthermore, to a certain extent, samples constructed
from the same sentence with different long forms are
independent during our training stage. It might lose more subtle
information among them. Therefore, recent methods such as
self-training
          <xref ref-type="bibr" rid="ref23 ref8">(Peng et al. 2019; Chi et al. 2020)</xref>
          ,
adversarial learning
          <xref ref-type="bibr" rid="ref12 ref19 ref34">(Goodfellow, Shlens, and Szegedy 2015;
Miyato, Dai, and Goodfellow 2017; Zhu et al. 2021)</xref>
          , and
contrastive learning
          <xref ref-type="bibr" rid="ref13">(Hadsell, Chopra, and LeCun 2006)</xref>
          are
worth studying to further improve the performance.
        </p>
      </sec>
    </sec>
    <sec id="sec-5">
      <title>Conclusions</title>
      <p>An obstacle to scientific document understanding is the
widespread use of acronyms which are shortened forms of
long technical phrases. Acronym disambiguation aims to
find the correct meaning of an ambiguous acronym in a
given text. However, it is challenging and expensive to
obtain large-scale high-quality annotated data in the scientific
domain. In this paper, we present a hierarchical dual-path
BERT method coined hdBERT for acronym
disambiguation to resolve the special challenges in this scenario. The
method is equipped with pretrained models RoBERTa and
SciBERT and integrates their dual-path representations
simultaneously to leveraging domain agnostic and specific
knowledge. Experiments on real-world datasets demonstrate
the effectiveness of the proposed approach. It achieves
competitive performance and outperforms state-of-the-art
methods among various evaluation metrics. Moreover, there are
still many research opportunities in this task, approaches
such as self-training, adversarial learning, and contrastive
learning are worth studying to further improve the
performance.</p>
    </sec>
    <sec id="sec-6">
      <title>Acknowledgments</title>
      <p>We thank the organizers of acronym identification and
disambiguation competitions and the reviewers for their
valuable comments and suggestions.</p>
    </sec>
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