
solutions, multi-task learning looks more promising due to
their potential relationship of text semantics.
More important and difficult is TagRec (Tag Recommenda-
tion) task. Recently, session-based recommendation methods
[85], [87] obtain satisfactory results to recommend products
and movies. Moreover, sequence-based approaches [39], [73]
are good at modeling sequences in the recommender system.
However, it is still challenging to extract fruitful information
from our various data and address a sequential recommenda-
tion problem. Besides, conventional sequential recommenda-
tion suffers from cold start issues.
From the model perspective, we collect multifarious data
types and relations, where a heterogeneous graph ought to
be constructed for reducing the impact of data sparsity in
cold start. On the one hand, a heterogeneous graph can also
alleviate the long tail problem to a certain extent, since it
explores the topological information of unpopular tags in a
network. On the other hand, the valuable sequential clicks’
information also deserves careful consideration. We propose
a novel hierarchical end-to-end model based on multiple at-
tention mechanisms, which leverages node attention, metapath
attention and contextual attention to respectively measure the
relationship between different node neighbors, the importance
of information transmission paths and the influence of sequen-
tial behaviors.
Further, system implementation and deployment are also
crucial to real-world industrial customer service. Our online
service, including response to answers, recommended tags
and predicted questions, should be finished within tens of
milliseconds. Nowadays, our deployed system in an indus-
trial production environment has already supported hundreds
thousands of SMEs and millions of users, where more than
ten thousand customer questions are solved every day.
Our contributions can be summarized as follows:
• To the best of our knowledge, it is the first work to reveal
model and system details of intelligent cloud customer
service with tag recommendation deployed in the real
world;
• An automatic way is introduced to collect Q&A pairs, and
a new BERT-based multi-task learning model is proposed
to mine valuable tags;
• We propose a novel model for tag recommendation,
which significantly outperforms several state-of-the-art
baseline algorithms both on offline and online evalua-
tions;
• System implementation and deployment details are un-
covered, which guarantees online service timely response
with about 100 ms.
II. RELATED WORK
In this section, we review related studies in Q&A chatbot,
tag recommendation, graph neural network based recommen-
dation and sequential recommendation.
A. Question and Answering Chatbot
Intelligent personal assistant, such as Microsoft’s Cortana
1
,
Amazon’s Alexa
2
, Apple’s Siri
3
, Baidu’s Xiaodu
4
and Al-
ibaba’s TmallGenie
5
, provides new human-computer interac-
tion experience to help people complete their daily affairs.
As a comparison, intelligent customer service system, such as
Microsoft’s SuperAgent [11], Alibaba’s AliMe [66], jd.com’s
JIMI [99] and Ant Financial’s AntProphet [5], aims to solve
the user’s questions about products and services. Our IntelliTag
helps SMEs solve their customer service issue through its
cloud service. From a technical perspective, rule-based and
template-based methods were first explored [82], [84]. Data-
driven approaches have recently achieved promising perfor-
mance, and two mainstreams are gradually formed, including
information retrieve [38], [40], [90], [91] and sequence-to-
sequence generation based techniques [48], [49], [71]. How-
ever, most previous studies focus on the dialogue system and
seldom explore tag recommendations in this field.
B. Tag Recommendation
Tag recommendation, as a problem of recommendation area,
are often divided into two main categories: user-centered and
tag-centered cases. The former builds the foundation on the
user’s personal data to predict tags. Multilayer perceptron
models were first applied to address the problems in recom-
mender systems, such as Wide and Deep [9], auto-encoder
[79], deep semantic neural networks [88], [89]. Factorization-
based methods [28], [70] were later introduced and achieved
better effectiveness. In contrast, the task of tag-centered rec-
ommendation mines the associated relationship between tags
and documents. Besides efficient linear FastText [43], CNN
(Convolutional Neural Network) was introduced to measure
the semantic information [83]. Also, LSTM (Long Short-Term
Memory) based models [51], [98] were adopted to characterize
the sequential nature of the text, and more methods with
attention were introduced to describe the importance of local
information [26], [52], [58]. Our task locates in a tag-centered
scenario, different from previous studies due to the integration
of various information.
C. Graph Neural Network based Recommendation
A graph is a kind of data structure to build a bridge between
different types of entities. In recent years, GNN (Graph
Neural Network) based approaches attract much attention.
Several unsupervised learning based models [3], [15], [27],
[64] were first proposed to generate node embeddings using
the topological information of graph structure. With the full
use of label information, graph convolutional network based
approaches [30], [45], [61] achieved better performance. To
characterize the fine-grained interaction in graphs, various
attention based GNNs are proposed to locate important or
1
https://www.microsoft.com/en-us/cortana
2
https://developer.amazon.com/en-US/alexa
3
https://www.apple.com/siri
4
https://dumall.baidu.com
5
https://en.wikipedia.org/wiki/Tmall Genie
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