<!DOCTYPE article PUBLIC "-//NLM//DTD JATS (Z39.96) Journal Archiving and Interchange DTD v1.0 20120330//EN" "JATS-archivearticle1.dtd">
<article xmlns:xlink="http://www.w3.org/1999/xlink">
  <front>
    <journal-meta />
    <article-meta>
      <title-group>
        <article-title>Agent Smith: Machine Teaching for Building Question Answering Agents</article-title>
      </title-group>
      <contrib-group>
        <contrib contrib-type="author">
          <string-name>Ashok Goel</string-name>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Harshvardhan Sikka</string-name>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Eric Gregori</string-name>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <aff id="aff0">
          <label>0</label>
          <institution>Design and Intelligence Lab, School of Interactive Computing, Georgia Institute of Technology</institution>
          ,
          <addr-line>North Ave NW, Atlanta, GA 30332</addr-line>
          ,
          <country country="US">USA</country>
        </aff>
      </contrib-group>
      <abstract>
        <p>Building AI agents can be costly. Consider a question answering agent such as Jill Watson that automatically answers students' questions on the discussion forums of online classes based on their syllabi and other course materials. Training a Jill on the syllabus of a new online class can take a hundred hours or more. Machine teaching - interactive teaching of an AI agent using synthetic data sets - can reduce the training time because it combines the advantages of knowledge-based AI, machine learning using large data sets, and interactive human-in-loop training. We describe Agent Smith, an interactive machine teaching agent that reduces the time taken to train a Jill for a new online class by an order of magnitude.</p>
      </abstract>
      <kwd-group>
        <kwd>eol&gt;AI</kwd>
        <kwd>education</kwd>
        <kwd>higher education</kwd>
        <kwd>human-AI interaction</kwd>
        <kwd>machine teaching</kwd>
        <kwd>machine learning</kwd>
        <kwd>online learning</kwd>
        <kwd>virtual assistant</kwd>
      </kwd-group>
    </article-meta>
  </front>
  <body>
    <sec id="sec-1">
      <title>1. Introduction</title>
      <p>
        Intelligent systems, and virtual assistants in particular, have proliferated in their utility and
application across a variety of domains [
        <xref ref-type="bibr" rid="ref1">1</xref>
        ]. This includes online education and learning, a
domain that has rapidly gained in popularity over the past decade. The unprecedented scale
of online education, and other domains including remote work, has resulted in a variety of
new problems ripe for AI to address. For example, a frequent criticism of online learning
environments is their notably low retention rates [
        <xref ref-type="bibr" rid="ref2">2</xref>
        ] and lower student satisfaction [
        <xref ref-type="bibr" rid="ref3">3</xref>
        ]. Another
issue with these learning environments is the lack of community resulting from the absence of
face to face interactions among learners [
        <xref ref-type="bibr" rid="ref4 ref5">4, 5</xref>
        ]. Virtual assistants provide unique approaches
and solutions to many of the issues referenced above. When considering the sheer quantity
of problems that present themselves at the internet scale, there are a staggering number of
opportunities that present themselves for virtual assistants. One such virtual assistant, the Jill
Watson Q&amp;A system, aims to enhance and support instructor and learners in online learning
environments through automatic question answering, thereby enhancing teacher presence[
        <xref ref-type="bibr" rid="ref6 ref7">6, 7</xref>
        ].
      </p>
      <p>
        A key challenge in the development of virtual assistants aiming to solve the issues mentioned
above, and intelligent systems more generally, is designing, training, and configuring them
to be efective in new contexts [
        <xref ref-type="bibr" rid="ref8 ref9">8, 9</xref>
        ]. This requires the involvement of a domain expert to
appropriately serve as an teacher, efectively “teaching” the machine learning system to solve
its target task in a given domain. However, teaching intelligent systems and virtual assistants
can be a costly and dificult process, often resulting in an enormous amount of person hours
required on the part of the domain expert [
        <xref ref-type="bibr" rid="ref10">10</xref>
        ]. Machine Teaching is a collection of approaches
explicitly aimed at solving the dificulties that lie in enabling domain experts to efectively
teach machine learning systems [
        <xref ref-type="bibr" rid="ref10 ref11 ref12 ref13 ref8 ref9">10, 8, 9, 11, 12, 13</xref>
        ]. In developing easy and fast approaches to
teaching machines, the space of potential opportunities across a wide variety of domains opens
up.
      </p>
      <p>In this paper, we present Agent Smith, an interactive machine teaching environment that
helps rapidly train custom Jill Watson Q&amp;A agents in new domains, saving domain experts
hundreds of hours in “teaching” time. First, we explore the capabilities of Jill Watson agents in
online learning environments. Then, we outline the role, process, and underlying mechanisms
in the Agent Smith system. Following this, we demonstrate the Agent Smith1 process in an
example classroom scenario, moving from mapping the domain of classroom information to
a machine readable format through template question formation and dataset generation, and
ifnally classification model training. Subsequently, we present empirical evidence for the success
of Agent Smith in its objective of saving users time when training a new Jill Watson system,
and statistics about its deployments. Finally, we discuss the implications of this approach as
well as related work and future directions.</p>
    </sec>
    <sec id="sec-2">
      <title>2. Question Answering in Jill Watson</title>
      <p>The Jill Watson Q&amp;A agent aims to enhance and support instructor and learners in online
learning environments. It accomplishes this through facilitating routine question answering reducing
the associated burden on the part of the course instructor. This in turn allows instructors to
leverage their time and presence more efectively in large scale learning environments with
many students. As a result, instructors can reach more learners efectively and spend more
time engaging with learners. For learners, Jill Watson provides enhanced learning assistance,
increasing learner engagement in online learning environments by answering questions quickly
and efectively.</p>
      <p>The current Jill Watson agent is the result of several iterations of design, development, and
evaluation mostly in the context of the Online Master of Science in Computer Science (OMSCS,
https://omscs.gatech.edu) program at Georgia Tech, which was launched in 2014. In the OMSCS
setting, students would interact with the professor and teaching assistants through online
discussion forums like Piazza, as well as through learning management systems (LMS) like
Canvas. In the early days of the OMSCS, the problem of teacher presence mitigation was clearly
identified. For example, during the first deployment of the online course on Knowledge Based
1The name "Agent Smith" is inspired by the character with the same name in the film "the Matrix", an agent
who could clone himself. Here the machine teaching process using Agent Smith creates, or "clones", Jill Watson for
each new context.
AI (KBAI,
https://omscs.gatech.edu/cs-7637-knowledge-based-artificial-intelligence-cognitivesystems), students posted hundreds of questions on the associated discussion forums,
immediately resulting in dificulties for the instruction team to successfully answer them all. This
prompted the development of the first version of Jill Watson, a virtual teaching assistant named
Jill Watson. The goal behind Jill Watson was similar to the recent version of Jill Watson:
automatically answering questions that popped up frequently related to core syllabus information.
This version of Jill Watson, referred to as Jill Watson 2016, used a collection of question and
answer pairs organized into various question categories in a preliminary grouping. Following
this, the design of Jill Watson was revised and iterated upon, resulting in several important
characteristics. Rather than focus on a databank of question and answer pairs, a novel ontology
of class syllabi was developed, with diferent course syllabus information being organized
around this ontology for use by the Jill Watson system.</p>
      <p>The most recent version of Jill Watson provides increased question answering capabilities
across a variety of domains beyond the original online learning scenario. At a high level,
Jill Watson uses a hybrid classification approach to separate and answer various questions
pertaining to a course syllabus successfully, demonstrated in Figure 2. The first stage in this
process uses statistical machine learning methods to categorize incoming questions and label
their underlying intents. Following this, a knowledge based classifier parses the question and
structures an appropriate response from an underlying knowledge base of relevant course
related information.</p>
    </sec>
    <sec id="sec-3">
      <title>3. Machine Teaching in Agent Smith</title>
      <sec id="sec-3-1">
        <title>3.1. Agent Smith Overview</title>
        <p>Jill Watson Q&amp;A agents are able to support a variety of domains, notably including instructors
and learners in online learning environments. However, the utility of developing a new Jill
Watson agent for a given class instance or a new domain only makes sense if it is afordable
from the perspectives of labor and time associated with each new configuration. Building new
Jill Watson agents from unstructured documents like class syllabi or job descriptions often
requires the time and labor of an expert in the domain area, which is inherently costly in many
scenarios.</p>
        <p>To resolve this constraint, we introduce Agent Smith, an interactive machine teaching
environment for developing Jill Watson agents in new domains. Agent Smith has the explicit goal
of making it easy and eficient for domain experts to generate custom Jill Watson systems.</p>
        <p>Agent Smith uses an knowledge-based process similar to the one used by researchers and
domain experts when configuring a new Jill Watson instance. At a high level, the Agent Smith
environment works by operating on two distinct inputs. The first is the aforementioned ontology
that defines the domain or the application area, referred to generally as the Knowledge Base
(KB). Conceptually, the Agent Smith generator uses a form for events (When is an assignment
due?) and semantic memory for facts and concepts (What is the course late work policy?). The
KB contains concepts and relations that form the body of the knowledge that an Jill Watson
Agent will seek to explain. The other important input to the Agent Smith system is a set of
question templates that capture the structural form of questions asked by potential users in
the domain. In the course context, these general templates may capture questions related to
deadlines, key terms, topics covered in diferent areas of the course, etc.</p>
        <p>Agent Smith combines these two knowledge bases as part of a combinatorial generation
process to create large sets of questions and their associated intents. A visual overview of this
process is given in Figure 4. These question-intent pairs can then be used to train the machine
learning classifier used in a Jill Watson agent. The overall result of the Agent Smith system is a
much faster turnaround time in training a new Jill Watson agent and a systematic approach to
achieving a high degree of question coverage for a target domain. Importantly, using Agent
Smith, the course creator can create an agent in less than 20 hours, saving the course creator
over 100 hours in answering questions a typical online virtual classroom. In the next section,
we walk through an example of Agent Smith in action, demonstrating how the agent smith
process results in a trained Jill Watson agent for a specific class.</p>
      </sec>
      <sec id="sec-3-2">
        <title>3.2. Agent Smith in Action</title>
        <p>Agent Smith has been applied to building Jill Watson Agents in several courses as part of the
OMSCS program at the Georgia Institute of Technology. Here, we walk through the Agent
Smith process to build a Jill Watson agent for the Knowledge Based Artificial Intelligence course
taught in the OMSCS program during the summer of 2020, demonstrating the knowledge bases
and the process behind their construction, the template questions and the process behind their
creation, the generative process and final dataset, and the trained classifier.</p>
        <p>The first step in enabling the Agent Smith system to rapidly train Jill Watson Q&amp;A agents is
to map the course domain to the unstructured and structured databases mentioned earlier. This
is done through reviewing examples of the domain that is to be defined and creating a taxonomy
based on similarities in the domain examples. Categories in the taxonomy are assigned a label
for the purpose of associating potential training questions with a response, where the focus is
that each label is unique. An example excerpt of a high level taxonomy for courses is given in
Figure 5.</p>
        <p>Following the creation of a taxonomy and its associated categories, structured entities and
unstructured categories can be identified, defined by the granularity and structure of the
associated information. These categories and their associated information are mapped to the
structured and unstructured databases. We include the schemas in Figure 7. The structured table
captures entities explicitly specified in its schema, while the unstructured table aims to capture
information that does not hold explicit identified entities, and presents more general information.
In practice, this means the structured table has a set of specific pieces of information associated
with each category captured in its schema, while the unstructured table contains unstructured
text responses associated with the category. These tables are the same tables used by the Jill
Watson agent during runtime when answering questions.</p>
        <p>Following the mapping of the domain to the unstructured and structured knowledge bases
described above, the next important step is to collect a set of questions that will likely be asked
about a given domain, the Knowledge Based AI class in our example. These questions are
then mapped to a general list of template questions and their associated intents. Template
questions seek to capture general forms of questions that occur within categories in the domain,
representing a large set of potential questions. These templates were manually designed by
extracting common patterns in corpuses of student question data gathered from previous
deployments of Jill Watson in educational courses in the OMSCS. Question analysis approaches,
including the frequency of diferent n-gram occurrences in the dataset is used to highlight
patterns in questions and the objects they pertain to. A high level overview of this process can
be seen in Figure 6. This is a preliminary approach, and we are exploring using large natural
language processing models trained on general text data to augment template design in future
work. An example schema for the database of template questions is given in Figure 7.</p>
        <p>In Table 1, we demonstrate example template questions for a subset of categories in the
domain, along with the number of total templates per category. We can see that diferent
categories hold a diferent number of question templates as there are varied structural forms
present in those categories as compared to others. For example, the “coursematerials” category
contains 85 template variations, while “teachingstaf” only contains 9.</p>
        <p>With the creation of the domain knowledge base, in both its structured and unstructured
forms, as well as the template questions database, Agent Smith can be used to create a large
dataset of example question answer pairs to train a Jill Watson Q&amp;A agent. When used, the
Agent Smith system combinatorially combines template questions with various structured and
unstructured keywords that represent the categories in both sections of the domain database.
The result is a dataset of questions orders of magnitude larger than previously hand collected
and labeled datasets for the KBAI course, in a fraction of the time. In Table 2, we demonstrate a
few examples of example questions generated from some of the templates demonstrated in the
previous table, along with their associated intents.</p>
        <p>Following the running of Agent Smith on the KBAI knowledge bases and template question
dataset created from the Fall 2020 version of the class, 24,587 questions and intent pairs were
created and subsequently used to train the machine learning classifier underlying the 2D
classification portion of the Jill Watson Q&amp;A agent.</p>
        <p>The core focus of Agent Smith is to reduce the time cost of developing a new Jill Watson
Agent in a domain. We estimate the time cost for creating, training, and configuring Jill Watson
was around 500 person hours in 2016. Through the use of the Agent Smith machine teaching
system, the estimated time cost of the development of a new Jill Watson agent in a given domain
is around 25 person hours, and can be less. Notably, Agent Smith has been deployed and used
in more than 20 course deployments over the past few years in the OMSCS program, and has
also enabled the creation of Jill Watson style agents in other domains.</p>
      </sec>
    </sec>
    <sec id="sec-4">
      <title>4. Discussion</title>
      <sec id="sec-4-1">
        <title>4.1. Related Work</title>
        <p>
          Agent Smith draws from ideas in both the field of data augmentation and the field of machine
teaching. Data augmentation is an area focusing on methods of increasing training data with
the need to go and collect more data [
          <xref ref-type="bibr" rid="ref14">14</xref>
          ]. Data Augmentation, and even Data Augmentation
approaches to Natural Language Processing [
          <xref ref-type="bibr" rid="ref15">15</xref>
          ], covers a large variety of approaches. In this
section we focus on related work in Data Augmentation in the area of rule based approaches
and data augmentation techniques used for Q and A applications. Easy Data Augmentation, or
EDA, proposes using random perturbation operations to include random insertion, swaps, and
deletions [
          <xref ref-type="bibr" rid="ref16">16</xref>
          ]. Linguistic knowledge based approaches have also been proposed, incorporating
prior knowledge to form the augmentation, and templates have been used successfully in
        </p>
        <p>Categories
coursedescription
teachingstaff</p>
        <p>officehours
lateworkpolicy
importantdates</p>
        <p>learning
courseprerequisites
coursematerials</p>
        <p>definition
Will we learn about user in this class?</p>
        <p>Who teaches this class?
When are ofice hours this week?</p>
        <p>When is the object?</p>
        <p>What are the learning goals of this class?
Do we need to know object to take this course?</p>
        <p>What are the object for the course?
Can you give an explanation for object?
Total Templates
27
9
13
11
8
20
47
18
85
14
intellectualpropertypolicy</p>
        <p>Can I post my work on a public platform?
disabilityaccomodations</p>
        <p>Where can I find information about Disability Services?</p>
        <p>
          What is the penalty for submitting work past the deadline? 31
Q&amp;A applications prior to this as well [
          <xref ref-type="bibr" rid="ref17 ref18">17, 18</xref>
          ]. Our approach makes use of manually designed
templates by educational technology researchers. This is appropriate for the generation of Jill
Watson agents due to the niche nature of the educational context as opposed to the general
language domain that other approaches may operate in.
        </p>
        <p>The field of Machine Teaching is more focused, and includes a few notable works. Simard et
coursedescription</p>
        <p>Will we learn about artificial intelligence in this class?</p>
        <p>Generated Question
When is the withdraw date?</p>
        <p>When is the start date?
Do we need to know python to take this course?</p>
        <p>Do we need to know C to take this course?
What are the course materials for the course?</p>
        <p>
          What are the websites for the course?
al propose a perspective on machine teaching that focuses on improving the eficacy of teachers,
putting a strong emphasis on the interaction of a teacher with the data [
          <xref ref-type="bibr" rid="ref8">8</xref>
          ]. Most notably, they
advocate for interfaces that decouple the knowledge related to a particular machine learning
system from the interaction of a teacher, allowing domain experts not familiar with machine
learning systems to participate in teaching these systems. Zhu et al present machine teaching
in a more formal setting, characterizing a problem space that describes machine teaching
and all associated problems [
          <xref ref-type="bibr" rid="ref11 ref9">11, 9</xref>
          ]. Our approach focuses on combining knowledge-based AI
and machine learning techniques for designing a machine teaching approach and associated
processes for rapid teaching of hybrid machine learning systems.
        </p>
      </sec>
      <sec id="sec-4-2">
        <title>4.2. Future Work</title>
        <p>Going forward, there are several exciting areas of research in applying the Agent Smith system,
as well as Machine Teaching approaches in general. Enabling Machine Teaching systems to
teach explanatory agents to understand not just static, structured information, but also dynamic
information will allow for the rapid design and training of agents that can lend understanding
about the state of Software Systems. In particular, we seek to design Agent Smith such that it
can make use of knowledge of design of an AI agent including its internal states to build Jill
Watson Q&amp;A agents for explaining the functioning of the AI agent. Another notable area is to
include better teaching interfaces and data augmentation approaches that allow domain experts
to more easily configure an Agent Smith system to build Q&amp;A agents.</p>
      </sec>
    </sec>
    <sec id="sec-5">
      <title>5. Conclusion</title>
      <p>In this paper, we introduce a machine teaching system for the rapid training of Jill Watson Q &amp;
A agents in new online course settings. In particular, we demonstrate the process of mapping
a new course domain to a structured knowledge base, and explain how a newly developed
machine teaching approach, dubbed Agent Smith, can use this information to generate large
data sets of example questions that cover much of what a student may ask in these course
settings. We also demonstrate an example of Agent Smith in action, moving from the mapping
of a domain through to a trained agent in an example graduate course at the Georgia Institute
of Technology. Applying machine teaching to virtual assistants opens up an exciting set of
directions, including new interfaces rapidly building virtual assistants that understand and
model software systems, two areas which we intend on investigating in the future.</p>
      <sec id="sec-5-1">
        <title>5.1. Acknowledgements</title>
        <p>We are grateful to IBM for providing us with access to its Watson platform. Jill Watson and
Agent Smith have been developed at Georgia Tech independently. We thank the Jill Watson team
at Georgia Tech Design Intelligence Laboratory including Vrinda Nandan, Spencer Rugaber,
and Karan Taneja for many discussions about Agent Smith. We are grateful to Georgia Tech for
supporting this research through internal seed grants.
question answering, arXiv preprint arXiv:2004.10157 (2020).</p>
      </sec>
    </sec>
  </body>
  <back>
    <ref-list>
      <ref id="ref1">
        <mixed-citation>
          [1]
          <string-name>
            <given-names>M.</given-names>
            <surname>Dubiel</surname>
          </string-name>
          ,
          <string-name>
            <given-names>M.</given-names>
            <surname>Halvey</surname>
          </string-name>
          ,
          <string-name>
            <given-names>L.</given-names>
            <surname>Azzopardi</surname>
          </string-name>
          ,
          <article-title>A survey investigating usage of virtual personal assistants</article-title>
          , arXiv preprint arXiv:
          <year>1807</year>
          .
          <volume>04606</volume>
          (
          <year>2018</year>
          ).
        </mixed-citation>
      </ref>
      <ref id="ref2">
        <mixed-citation>
          [2]
          <string-name>
            <given-names>L.</given-names>
            <surname>Yuan</surname>
          </string-name>
          ,
          <string-name>
            <given-names>S.</given-names>
            <surname>Powell</surname>
          </string-name>
          ,
          <article-title>Moocs and open education: Implications for higher education (</article-title>
          <year>2013</year>
          ).
        </mixed-citation>
      </ref>
      <ref id="ref3">
        <mixed-citation>
          [3]
          <string-name>
            <given-names>J.</given-names>
            <surname>Daniel</surname>
          </string-name>
          ,
          <article-title>Making sense of moocs: Musings in a maze of myth, paradox and possibility</article-title>
          ,
          <source>Journal of interactive Media in education 2012</source>
          (
          <year>2012</year>
          ).
        </mixed-citation>
      </ref>
      <ref id="ref4">
        <mixed-citation>
          [4]
          <string-name>
            <given-names>F.</given-names>
            <surname>Hollands</surname>
          </string-name>
          ,
          <string-name>
            <given-names>D.</given-names>
            <surname>Tirthali</surname>
          </string-name>
          ,
          <article-title>Moocs: Expectations and reality: Full report, center for benefit-cost studies of education. teachers college</article-title>
          , columbia university (usa),
          <year>2014</year>
          .
        </mixed-citation>
      </ref>
      <ref id="ref5">
        <mixed-citation>
          [5]
          <string-name>
            <given-names>Q.</given-names>
            <surname>Wang</surname>
          </string-name>
          ,
          <string-name>
            <given-names>S.</given-names>
            <surname>Jing</surname>
          </string-name>
          ,
          <string-name>
            <given-names>I.</given-names>
            <surname>Camacho</surname>
          </string-name>
          ,
          <string-name>
            <given-names>D.</given-names>
            <surname>Joyner</surname>
          </string-name>
          ,
          <string-name>
            <given-names>A.</given-names>
            <surname>Goel</surname>
          </string-name>
          ,
          <article-title>Jill watson sa: Design and evaluation of a virtual agent to build communities among online learners</article-title>
          ,
          <source>in: Extended Abstracts of the 2020 CHI Conference on Human Factors in Computing Systems</source>
          ,
          <year>2020</year>
          , pp.
          <fpage>1</fpage>
          -
          <lpage>8</lpage>
          .
        </mixed-citation>
      </ref>
      <ref id="ref6">
        <mixed-citation>
          [6]
          <string-name>
            <given-names>A.</given-names>
            <surname>Goel</surname>
          </string-name>
          , L. Polepeddi,
          <article-title>Jill watson: A virtual teaching assistant for online education</article-title>
          , In Education at Scale:
          <article-title>Engineering Online Learning</article-title>
          and Teaching,
          <string-name>
            <given-names>C.</given-names>
            <surname>Dede</surname>
          </string-name>
          ,
          <string-name>
            <given-names>J.</given-names>
            <surname>Richards</surname>
          </string-name>
          , &amp; B.Saxberg (editors),
          <article-title>Chapter 7</article-title>
          , NY: Routledge. (
          <year>2018</year>
          ).
        </mixed-citation>
      </ref>
      <ref id="ref7">
        <mixed-citation>
          [7]
          <string-name>
            <given-names>B.</given-names>
            <surname>Eicher</surname>
          </string-name>
          ,
          <string-name>
            <given-names>L.</given-names>
            <surname>Polepeddi</surname>
          </string-name>
          ,
          <string-name>
            <given-names>A.</given-names>
            <surname>Goel</surname>
          </string-name>
          ,
          <article-title>Jill watson doesn't care if you're pregnant: Grounding ai ethics in empirical studies</article-title>
          ,
          <source>in: Proceedings of the 2018 AAAI/ACM Conference on AI, Ethics, and Society</source>
          ,
          <year>2018</year>
          , pp.
          <fpage>88</fpage>
          -
          <lpage>94</lpage>
          .
        </mixed-citation>
      </ref>
      <ref id="ref8">
        <mixed-citation>
          [8]
          <string-name>
            <given-names>P. Y.</given-names>
            <surname>Simard</surname>
          </string-name>
          ,
          <string-name>
            <given-names>S.</given-names>
            <surname>Amershi</surname>
          </string-name>
          ,
          <string-name>
            <given-names>D. M.</given-names>
            <surname>Chickering</surname>
          </string-name>
          ,
          <string-name>
            <given-names>A. E.</given-names>
            <surname>Pelton</surname>
          </string-name>
          ,
          <string-name>
            <given-names>S.</given-names>
            <surname>Ghorashi</surname>
          </string-name>
          ,
          <string-name>
            <given-names>C.</given-names>
            <surname>Meek</surname>
          </string-name>
          , G. Ramos,
          <string-name>
            <given-names>J.</given-names>
            <surname>Suh</surname>
          </string-name>
          ,
          <string-name>
            <given-names>J.</given-names>
            <surname>Verwey</surname>
          </string-name>
          ,
          <string-name>
            <given-names>M.</given-names>
            <surname>Wang</surname>
          </string-name>
          , et al.,
          <article-title>Machine teaching: A new paradigm for building machine learning systems</article-title>
          ,
          <source>arXiv preprint arXiv:1707.06742</source>
          (
          <year>2017</year>
          ).
        </mixed-citation>
      </ref>
      <ref id="ref9">
        <mixed-citation>
          [9]
          <string-name>
            <given-names>X.</given-names>
            <surname>Zhu</surname>
          </string-name>
          ,
          <article-title>Machine teaching: An inverse problem to machine learning and an approach toward optimal education</article-title>
          ,
          <source>in: Proceedings of the AAAI Conference on Artificial Intelligence</source>
          , volume
          <volume>29</volume>
          ,
          <year>2015</year>
          .
        </mixed-citation>
      </ref>
      <ref id="ref10">
        <mixed-citation>
          [10]
          <string-name>
            <given-names>A.</given-names>
            <surname>Goel</surname>
          </string-name>
          ,
          <article-title>Ai-powered learning: making education accessible, afordable, and achievable</article-title>
          , arXiv preprint arXiv:
          <year>2006</year>
          .
          <year>01908</year>
          (
          <year>2020</year>
          ).
        </mixed-citation>
      </ref>
      <ref id="ref11">
        <mixed-citation>
          [11]
          <string-name>
            <given-names>X.</given-names>
            <surname>Zhu</surname>
          </string-name>
          ,
          <string-name>
            <given-names>A.</given-names>
            <surname>Singla</surname>
          </string-name>
          ,
          <string-name>
            <given-names>S.</given-names>
            <surname>Zilles</surname>
          </string-name>
          ,
          <string-name>
            <given-names>A. N.</given-names>
            <surname>Raferty</surname>
          </string-name>
          ,
          <article-title>An overview of machine teaching</article-title>
          , arXiv preprint arXiv:
          <year>1801</year>
          .
          <volume>05927</volume>
          (
          <year>2018</year>
          ).
        </mixed-citation>
      </ref>
      <ref id="ref12">
        <mixed-citation>
          [12]
          <string-name>
            <given-names>W.</given-names>
            <surname>Liu</surname>
          </string-name>
          ,
          <string-name>
            <given-names>B.</given-names>
            <surname>Dai</surname>
          </string-name>
          ,
          <string-name>
            <given-names>A.</given-names>
            <surname>Humayun</surname>
          </string-name>
          ,
          <string-name>
            <given-names>C.</given-names>
            <surname>Tay</surname>
          </string-name>
          ,
          <string-name>
            <given-names>C.</given-names>
            <surname>Yu</surname>
          </string-name>
          ,
          <string-name>
            <given-names>L. B.</given-names>
            <surname>Smith</surname>
          </string-name>
          ,
          <string-name>
            <given-names>J. M.</given-names>
            <surname>Rehg</surname>
          </string-name>
          ,
          <string-name>
            <surname>L. Song,</surname>
          </string-name>
          <article-title>Iterative machine teaching</article-title>
          ,
          <source>in: International Conference on Machine Learning, PMLR</source>
          ,
          <year>2017</year>
          , pp.
          <fpage>2149</fpage>
          -
          <lpage>2158</lpage>
          .
        </mixed-citation>
      </ref>
      <ref id="ref13">
        <mixed-citation>
          [13]
          <string-name>
            <given-names>D.</given-names>
            <surname>Weitekamp</surname>
          </string-name>
          ,
          <string-name>
            <given-names>E.</given-names>
            <surname>Harpstead</surname>
          </string-name>
          ,
          <string-name>
            <given-names>K. R.</given-names>
            <surname>Koedinger</surname>
          </string-name>
          ,
          <article-title>An interaction design for machine teaching to develop ai tutors</article-title>
          ,
          <source>in: Proceedings of the 2020 CHI Conference on Human Factors in Computing Systems</source>
          ,
          <year>2020</year>
          , pp.
          <fpage>1</fpage>
          -
          <lpage>11</lpage>
          .
        </mixed-citation>
      </ref>
      <ref id="ref14">
        <mixed-citation>
          [14]
          <string-name>
            <given-names>C.</given-names>
            <surname>Shorten</surname>
          </string-name>
          ,
          <string-name>
            <given-names>T. M.</given-names>
            <surname>Khoshgoftaar</surname>
          </string-name>
          ,
          <article-title>A survey on image data augmentation for deep learning</article-title>
          ,
          <source>Journal of Big Data</source>
          <volume>6</volume>
          (
          <year>2019</year>
          )
          <fpage>1</fpage>
          -
          <lpage>48</lpage>
          .
        </mixed-citation>
      </ref>
      <ref id="ref15">
        <mixed-citation>
          [15]
          <string-name>
            <given-names>S. Y.</given-names>
            <surname>Feng</surname>
          </string-name>
          ,
          <string-name>
            <given-names>V.</given-names>
            <surname>Gangal</surname>
          </string-name>
          ,
          <string-name>
            <given-names>J.</given-names>
            <surname>Wei</surname>
          </string-name>
          ,
          <string-name>
            <given-names>S.</given-names>
            <surname>Chandar</surname>
          </string-name>
          ,
          <string-name>
            <given-names>S.</given-names>
            <surname>Vosoughi</surname>
          </string-name>
          ,
          <string-name>
            <given-names>T.</given-names>
            <surname>Mitamura</surname>
          </string-name>
          ,
          <string-name>
            <given-names>E.</given-names>
            <surname>Hovy</surname>
          </string-name>
          ,
          <article-title>A survey of data augmentation approaches for nlp</article-title>
          ,
          <source>arXiv preprint arXiv:2105.03075</source>
          (
          <year>2021</year>
          ).
        </mixed-citation>
      </ref>
      <ref id="ref16">
        <mixed-citation>
          [16]
          <string-name>
            <given-names>J.</given-names>
            <surname>Wei</surname>
          </string-name>
          ,
          <string-name>
            <given-names>K.</given-names>
            <surname>Zou</surname>
          </string-name>
          , Eda:
          <article-title>Easy data augmentation techniques for boosting performance on text classification tasks</article-title>
          , arXiv preprint arXiv:
          <year>1901</year>
          .
          <volume>11196</volume>
          (
          <year>2019</year>
          ).
        </mixed-citation>
      </ref>
      <ref id="ref17">
        <mixed-citation>
          [17]
          <string-name>
            <given-names>J.</given-names>
            <surname>Singh</surname>
          </string-name>
          ,
          <string-name>
            <given-names>B.</given-names>
            <surname>McCann</surname>
          </string-name>
          ,
          <string-name>
            <given-names>N. S.</given-names>
            <surname>Keskar</surname>
          </string-name>
          ,
          <string-name>
            <given-names>C.</given-names>
            <surname>Xiong</surname>
          </string-name>
          ,
          <string-name>
            <given-names>R.</given-names>
            <surname>Socher</surname>
          </string-name>
          , Xlda:
          <article-title>Cross-lingual data augmentation for natural language inference and question answering</article-title>
          , arXiv preprint arXiv:
          <year>1905</year>
          .
          <volume>11471</volume>
          (
          <year>2019</year>
          ).
        </mixed-citation>
      </ref>
      <ref id="ref18">
        <mixed-citation>
          [18]
          <string-name>
            <given-names>A.</given-names>
            <surname>Asai</surname>
          </string-name>
          ,
          <string-name>
            <given-names>H.</given-names>
            <surname>Hajishirzi</surname>
          </string-name>
          ,
          <article-title>Logic-guided data augmentation and regularization for consistent</article-title>
        </mixed-citation>
      </ref>
    </ref-list>
  </back>
</article>