17 research outputs found
Towards Interpretable Deep Learning Models for Knowledge Tracing
As an important technique for modeling the knowledge states of learners, the
traditional knowledge tracing (KT) models have been widely used to support
intelligent tutoring systems and MOOC platforms. Driven by the fast
advancements of deep learning techniques, deep neural network has been recently
adopted to design new KT models for achieving better prediction performance.
However, the lack of interpretability of these models has painfully impeded
their practical applications, as their outputs and working mechanisms suffer
from the intransparent decision process and complex inner structures. We thus
propose to adopt the post-hoc method to tackle the interpretability issue for
deep learning based knowledge tracing (DLKT) models. Specifically, we focus on
applying the layer-wise relevance propagation (LRP) method to interpret
RNN-based DLKT model by backpropagating the relevance from the model's output
layer to its input layer. The experiment results show the feasibility using the
LRP method for interpreting the DLKT model's predictions, and partially
validate the computed relevance scores from both question level and concept
level. We believe it can be a solid step towards fully interpreting the DLKT
models and promote their practical applications in the education domain
Transcribing Content from Structural Images with Spotlight Mechanism
Transcribing content from structural images, e.g., writing notes from music
scores, is a challenging task as not only the content objects should be
recognized, but the internal structure should also be preserved. Existing image
recognition methods mainly work on images with simple content (e.g., text lines
with characters), but are not capable to identify ones with more complex
content (e.g., structured symbols), which often follow a fine-grained grammar.
To this end, in this paper, we propose a hierarchical Spotlight Transcribing
Network (STN) framework followed by a two-stage "where-to-what" solution.
Specifically, we first decide "where-to-look" through a novel spotlight
mechanism to focus on different areas of the original image following its
structure. Then, we decide "what-to-write" by developing a GRU based network
with the spotlight areas for transcribing the content accordingly. Moreover, we
propose two implementations on the basis of STN, i.e., STNM and STNR, where the
spotlight movement follows the Markov property and Recurrent modeling,
respectively. We also design a reinforcement method to refine the framework by
self-improving the spotlight mechanism. We conduct extensive experiments on
many structural image datasets, where the results clearly demonstrate the
effectiveness of STN framework.Comment: Accepted by KDD2018 Research Track. In proceedings of the 24th ACM
SIGKDD International Conference on Knowledge Discovery and Data Mining
(KDD'18
Exploiting Cognitive Structure for Adaptive Learning
Adaptive learning, also known as adaptive teaching, relies on learning path
recommendation, which sequentially recommends personalized learning items
(e.g., lectures, exercises) to satisfy the unique needs of each learner.
Although it is well known that modeling the cognitive structure including
knowledge level of learners and knowledge structure (e.g., the prerequisite
relations) of learning items is important for learning path recommendation,
existing methods for adaptive learning often separately focus on either
knowledge levels of learners or knowledge structure of learning items. To fully
exploit the multifaceted cognitive structure for learning path recommendation,
we propose a Cognitive Structure Enhanced framework for Adaptive Learning,
named CSEAL. By viewing path recommendation as a Markov Decision Process and
applying an actor-critic algorithm, CSEAL can sequentially identify the right
learning items to different learners. Specifically, we first utilize a
recurrent neural network to trace the evolving knowledge levels of learners at
each learning step. Then, we design a navigation algorithm on the knowledge
structure to ensure the logicality of learning paths, which reduces the search
space in the decision process. Finally, the actor-critic algorithm is used to
determine what to learn next and whose parameters are dynamically updated along
the learning path. Extensive experiments on real-world data demonstrate the
effectiveness and robustness of CSEAL.Comment: Accepted by KDD 2019 Research Track. In Proceedings of the 25th ACM
SIGKDD International Conference on Knowledge Discovery & Data Mining (KDD'19
QuesNet: A Unified Representation for Heterogeneous Test Questions
Understanding learning materials (e.g. test questions) is a crucial issue in
online learning systems, which can promote many applications in education
domain. Unfortunately, many supervised approaches suffer from the problem of
scarce human labeled data, whereas abundant unlabeled resources are highly
underutilized. To alleviate this problem, an effective solution is to use
pre-trained representations for question understanding. However, existing
pre-training methods in NLP area are infeasible to learn test question
representations due to several domain-specific characteristics in education.
First, questions usually comprise of heterogeneous data including content text,
images and side information. Second, there exists both basic linguistic
information as well as domain logic and knowledge. To this end, in this paper,
we propose a novel pre-training method, namely QuesNet, for comprehensively
learning question representations. Specifically, we first design a unified
framework to aggregate question information with its heterogeneous inputs into
a comprehensive vector. Then we propose a two-level hierarchical pre-training
algorithm to learn better understanding of test questions in an unsupervised
way. Here, a novel holed language model objective is developed to extract
low-level linguistic features, and a domain-oriented objective is proposed to
learn high-level logic and knowledge. Moreover, we show that QuesNet has good
capability of being fine-tuned in many question-based tasks. We conduct
extensive experiments on large-scale real-world question data, where the
experimental results clearly demonstrate the effectiveness of QuesNet for
question understanding as well as its superior applicability
R2DE: a NLP approach to estimating IRT parameters of newly generated questions
The main objective of exams consists in performing an assessment of students'
expertise on a specific subject. Such expertise, also referred to as skill or
knowledge level, can then be leveraged in different ways (e.g., to assign a
grade to the students, to understand whether a student might need some support,
etc.). Similarly, the questions appearing in the exams have to be assessed in
some way before being used to evaluate students. Standard approaches to
questions' assessment are either subjective (e.g., assessment by human experts)
or introduce a long delay in the process of question generation (e.g.,
pretesting with real students). In this work we introduce R2DE (which is a
Regressor for Difficulty and Discrimination Estimation), a model capable of
assessing newly generated multiple-choice questions by looking at the text of
the question and the text of the possible choices. In particular, it can
estimate the difficulty and the discrimination of each question, as they are
defined in Item Response Theory. We also present the results of extensive
experiments we carried out on a real world large scale dataset coming from an
e-learning platform, showing that our model can be used to perform an initial
assessment of newly created questions and ease some of the problems that arise
in question generation