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  <front>
    <journal-meta />
    <article-meta>
      <title-group>
        <article-title>SEVA: A Systems Engineer's Virtual Assistant</article-title>
      </title-group>
      <contrib-group>
        <contrib contrib-type="author">
          <string-name>Jitin Krishnan</string-name>
          <email>jkrishn2@gmu.edu</email>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Patrick Coronado</string-name>
          <email>patrick.l.coronado@nasa.gov</email>
          <xref ref-type="aff" rid="aff2">2</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Trevor Reed</string-name>
          <email>trevor.reed@jpl.nasa.gov</email>
          <xref ref-type="aff" rid="aff3">3</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Copyright held by the author(s). In A. Martin, K. Hinkelmann, A.</string-name>
          <xref ref-type="aff" rid="aff1">1</xref>
        </contrib>
        <aff id="aff0">
          <label>0</label>
          <institution>Department of Computer Science, George Mason University</institution>
        </aff>
        <aff id="aff1">
          <label>1</label>
          <institution>Gerber</institution>
          ,
          <addr-line>D. Lenat, F. van Harmelen, P. Clark (Eds.)</addr-line>
          ,
          <institution>Proceedings of, the AAAI 2019 Spring Symposium on Combining Machine Learning with Knowledge Engineering (AAAI-MAKE 2019). Stanford, University</institution>
          ,
          <addr-line>Palo Alto, California, USA, March 25-27, 2019.</addr-line>
          ,
          <country country="US">USA</country>
        </aff>
        <aff id="aff2">
          <label>2</label>
          <institution>Instrument Development Center, NASA Goddard Space Flight Center</institution>
        </aff>
        <aff id="aff3">
          <label>3</label>
          <institution>Robot Operations, NASA Jet Propulsion Laboratory</institution>
        </aff>
      </contrib-group>
      <abstract>
        <p>A Systems Engineer's Virtual Assistant (SEVA) is a novel attempt to bridge the gap between Natural Language Processing (NLP), Knowledge Base (KB) Construction research, and NASA's Systems Engineering domain. In this work, we propose the design of an explainable, human-in-the-loop, and interactive personal assistant system. The assistant will help a Systems Engineer in their daily work environment through complex information management and high-level questionanswering to augment their problem-solving abilities. We describe the fundamental characteristics of the assistant by understanding operational, functional, and system requirements from Systems Engineers and NASA's Systems Engineering Handbook. The assistant is designed to act as a workbench to manage dynamic information about projects and analyze hypothetical scenarios. It is also designed to make logical inferences and perform temporal reasoning by handling domain information and information related to schedule and resources. In addition, the system learns new information over time by interacting with its user and can perform case-based reasoning from previous experiences. The knowledge base design describes a novel hybrid approach to build a domainindependent common-sense framework with which domainspecific engineers can attune it and build their projects. Using these specific objectives and constraints, the architecture of a personal assistant is proposed. Main contributions of this design paper are Systems Engineering (SE) domain analysis, a survey of existing research, preliminary experiments using the state-of-the-art systems to explore the feasibility, a proposal of a complete architecture with component level detail, and identification of areas that require further research and development.</p>
      </abstract>
      <kwd-group>
        <kwd>Natural Language Processing</kwd>
        <kwd>Knowledge Base Construction</kwd>
        <kwd>Question-Answering</kwd>
        <kwd>Intelligent Agents</kwd>
        <kwd>Explainable AI</kwd>
        <kwd>Systems Engineering</kwd>
        <kwd>Ontology</kwd>
      </kwd-group>
    </article-meta>
  </front>
  <body>
    <sec id="sec-1">
      <title>INTRODUCTION</title>
      <p>Intelligent personal assistants have drawn attention in recent
years due to their ubiquitous nature of making human lives
easier. However, practical use of such personal assistants by
individual scientists or engineers, such as those at NASA,
is still very limited due to the risk-averse nature of
engineering projects, users’ steep learning curves in studying the
unnecessary details of a new system, and the assistant’s
inability to capture the relevant complexity of the domain. In
addition, explainability of answers plays a key role in such
AI systems where trust in the answers is paramount. It is a
dream for most scientists and engineers to have a personal
assistant who takes care of the tedious book-keeping aspects
and assists them in creative problem solving. Systems
Engineers (SE) deal with large amounts of information in their
everyday work. Their role in technical project planning
requires handling this information and keeping track of diverse
requirements, changing variables, resources, and schedules.
This extensive information assimilation is both tedious and
error-prone. The ability of SEs could be greatly enhanced
by a system that could handle such tasks. SEVA is being
developed with this goal in mind: to assist SEs and enhance
their problem-solving abilities by keeping track of the large
amounts of information of a NASA specific project and
using the information to answer queries from the user.</p>
    </sec>
    <sec id="sec-2">
      <title>BACKGROUND AND MOTIVATION</title>
      <p>
        NASA’s state-of-the-art approach to computer-aided
Systems Engineering projects is Model Based Systems
Engineering (MBSE). It is a model-centric approach which
supports all phases of SDLC (System Development Life Cycle)
with which SEs can design their large scale projects. Two
key problems that MBSE tackle are collaboration of
different domains and conversion of documents to digital
models. MBSE also has a similar goal in mind as SEVA: to
facilitate understanding, aid decision-making, examine
hypothetical scenarios, and explain, control, and predict events
        <xref ref-type="bibr" rid="ref26">(Hart 2015)</xref>
        . MBSE is expected to solve the problems of
inadequacy in information-capture and dynamic nature of
SE’s design documentations such as System Block
Diagrams, Electrical Interconnect List, and Mass Equipment
List
        <xref ref-type="bibr" rid="ref21">(Fosse et al. 2014)</xref>
        . MBSE aims to tackle the problems
of lack of a common language between different disciplines
using a formal language called SysML. However, systems
such as MBSE present a steep learning curve for new
learners who will need to learn the system or a new language.
      </p>
      <p>
        On the other end of the learning curve are popular
intelligent assistants such as Siri providing proactive assistance on
a very specific set of contextual tasks such as calling a friend,
sending a message, or making a dinner reservation. These
assistants are not knowledge systems which can assist a user
in complex tasks such as engineering projects or disease
diagnosis. There is little reason for such assistants to
maintain large scale ontologies. For example, the rather small
and active ontology maintained by Siri is sufficient enough
to aid its task-based design
        <xref ref-type="bibr" rid="ref23">(Gruber 2009)</xref>
        . On the other
hand, large scale knowledge systems such as IBM Watson
perform statistical inferencing to answer a question by
ingesting millions of documents. The main goal of Watson is
to essentially answer a question. Watson is trained by QA
sessions and answers are returned with probability or
confidence (Lee et al. 2016). Watson’s knowledge is a
compilation of knowledge from various domain experts. Thousands
of medical books can be ingested by Watson to create a large
scale knowledge system for disease diagnosis. Since Watson
used evidence gathering and scoring algorithms, ontologies
were not essential in the architecture
        <xref ref-type="bibr" rid="ref19">(Ferrucci et al. 2010;
2013)</xref>
        . On the other hand, SEVA’s domain is limited and
needs a knowledge base or an ontology which is complete
and can handle changing contextual facts. In addition, the
ability to say ‘I don’t know’ is an essential characteristic of
an explainable system.
      </p>
      <p>
        The Cyc project tried to perform human-like reasoning
by building a comprehensive system with common-sense
knowledge such as “water makes things wet”, “plants die
eventually”, etc
        <xref ref-type="bibr" rid="ref52">(Panton et al. 2006)</xref>
        . The idea was to create a
system that can serve as a foundation to all future expert
systems. However, millions of assertions are hand-coded to the
system and the amount of knowledge required to be learned
was one of the major criticisms of the project
        <xref ref-type="bibr" rid="ref15">(Domingos
2015)</xref>
        . In our work, we aim to construct a scalable domain
specific common-sense knowledge base with SE facts.
      </p>
      <p>
        The MIT Programmer’s Apprentice Project
        <xref ref-type="bibr" rid="ref60 ref7">(Rich and
Waters 1987; Brooks 1997)</xref>
        , which ran in 1970s and 80s,
shares a similar spirit with SEVA. The goal was to study
knowledge representation formalism and reasoning in the
context of programming. The work realized the importance
of personal assistants performing mundane tasks and
incremental development of knowledge
        <xref ref-type="bibr" rid="ref60">(Rich and Waters 1987)</xref>
        which is also relevant in SEVA. Our work combines a
generalist (SE) with a specialist (SEVA) such that the specialist’s
knowledge base acts as a dynamic workbench for the
generalist.
      </p>
    </sec>
    <sec id="sec-3">
      <title>OPERATIONAL CONCEPT</title>
      <p>SEVA has 3 main categories of questions from which its
external interface requirements are based from: 1) Relational,
2) Recall, and 3) Hypothetical. Relational questions
determine the existence of links between entities. In ontological
terminology, links are verbs/predicates that connect subjects
and objects. The answer can be ‘Yes’, ‘No’, or ‘Unknown’.
For example, questions such as “Is Neon a noble gas?” or
“Can Aerogel capture a Niacin molecule moving at 5km/s?”
fall into this category. Recall, the next type, determines what
entity another entity is linked to. For example, questions
such as “What is the total mass of the spacecraft?” or “When
is the vibration test for the flight Main Electronics Box?” fall
into this category. Hypothetical questions are “what-if”
scenarios. For example, questions such as “What will be the
mass of Instrument X if component C is removed?”.</p>
      <p>Apart from direct recall of information and storage, four
major capabilities of this virtual assistant are defined based
on the various scenarios encountered by an SE: A) perform
reasoning tasks, B) handle temporal (time-related)
information, C) answer hypothetical (what-if) questions, and
D) learn from “experience”.</p>
      <sec id="sec-3-1">
        <title>Reasoning</title>
        <p>
          An ontology describes concepts, properties, and
relationships in formal languages such as first-order logic,
description logic, or horn clauses. Using reasoning skills on its
ontology, SEVA will be able to create new, indirect, or derived
information that are dependent on the existing knowledge.
Primary form of reasoning is related to the idea of
taxonomic or is-a relationship between two concepts
          <xref ref-type="bibr" rid="ref73">(Walton
2007)</xref>
          . For example, assume SEVA has the following
information in its knowledge base: fNeon is a noble gasg and
fNoble gases are odorlessg. From this information, an
inference engine can deduce that fNeon is odorlessg. SEVA’s
ontology consists of specific axioms from Description Logic
and rules defining the complexity and explainability of the
domain that is represented. The terms “reasoning engine”
and “inference engine” are used interchangeably throughout
this paper.
        </p>
      </sec>
      <sec id="sec-3-2">
        <title>Time</title>
        <p>SEVA handles three categories of time: 1) time-tagging
information, 2) processing time-related information, and
3) knowledge of tense. Every information in the assistant’s
knowledge base has to be time-tagged. This helps the
assistant in answering questions such as “What was the mass of
the nephelometer instrument three days ago?” or “When was
the test schedule changed for the second stage cryocooler?”.
The primary objective of time-tagging is to help the engineer
to temporarily track the change log history of all elements
of a project or task. Alternatively, processing time-related
information simply means to understand temporal
information in a sentence such as 06:23:43 for time, 07/11/2018 for
date, and to understand intervals of time such as ‘three hours
ago’ or ‘due in 5 hours’. Understanding tense is an obvious
capability necessary to perform the above two tasks, which
means to know grammatical terms such as is, was, ago, had,
initial, etc.</p>
      </sec>
      <sec id="sec-3-3">
        <title>Hypothetical Mode</title>
        <p>In hypothetical mode, an SE can ask ‘what if’ questions.
By entering the hypothetical mode, the user can
temporarily modify the information in the knowledge base.
‘Whatif’ questions such as “What is the Technology Readiness
Level(TRL) of instrument X, if it has been to space?” are a
combination of two tasks: 1) perform temporary updates
on the knowledge base and 2) ask questions as usual. In the
example, the knowledge base will be temporarily updated
with a new information: fInstrument X has been to spaceg.
The SE then asks the question fWhat is the TRL of
instrument X?g After exiting this mode, the knowledge base will
be restored to its original form without the temporary
updates. Hypothetical mode helps the SE in decision-making,
design support, and in analyzing various scenarios or
hypothetical models.</p>
      </sec>
      <sec id="sec-3-4">
        <title>Experience</title>
        <p>Two reasons for unsuccessful querying are 1) the entities
or concepts in the question are unknown to SEVA and 2)
entities are known but there is not enough information to
answer the question. In the first case, SEVA asks the SE a
series of questions to better understand the original question
and to fill the knowledge base with necessary information to
answer the question. For example, when the SE asks “What
is the mass of Neon?” and SEVA’s knowledge base has no
information about ‘Neon’, it will respond by inquiring “What
is Neon?”. The second case is a logical problem that applies
to relational questions where the ontology is missing the
predicate link. Assume that the entities ‘mass’ and ‘neon’
are in SEVA’s knowledge base. Suppose the SE asks “What
is the mass of instrument X?” SEVA understands every
entity in the question but has no link connecting them. There
are two ways to provide the unknown information: 1) help
the system to derive the answer by creating a logical case
through interaction (eg: “mass of an instrument is the sum
of its components”) or 2) provide the answer directly (eg:
“mass of instrument X is 5kg”). This type of user-assistant
interaction constitutes an ‘Experience’ and can be used if
similar cases appear in future question-answering sessions.
A key aspect of SEVA’s architecture is that an ‘Experience’
is context-driven; it is a function of questions, statements,
and rules or logic from the user. The type of learning we aim
to provide SEVA with is case-based contextual awareness.</p>
      </sec>
      <sec id="sec-3-5">
        <title>Nature of Input &amp; Querying</title>
        <p>SEVA takes input from various sources including operations
manuals and projects. In this work, we restrict to Natural
Language text as input. Other types of inputs are left as
future work. There are 4 types of interaction types in SEVA: 1)
information given to the assistant that undergoes natural
language processing and subsequently added to its knowledge
base, 2) basic user commands to enter and exit hypothetical
mode, undo an operation, etc., 3) a successful query where
the assistant responds with an answer, and 4) an
unsuccessful query (due to unknown concepts) which is tackled by
using interactive dialogues and case-based reasoning from
experience.</p>
      </sec>
      <sec id="sec-3-6">
        <title>Common-Sense Knowledge</title>
        <p>
          Creating a Common-Sense AI is an important and
challenging task in AI research today. Several research have
explored this topic, inspiring ones being projects such as
Mosaic Common Sense Knowledge Graphs and Reasoning
          <xref ref-type="bibr" rid="ref74">(Zellers et al. 2018)</xref>
          and Aristo System (AI2 Allen
Institute for Artificial Intelligence ). SEVA aims to construct a
targeted common-sense knowledge base which is
explainable, can be trusted, and is carefully populated from trusted
sources. This limits the usage of big data on semantic web
including the usage of DBpedia
          <xref ref-type="bibr" rid="ref39">(Lehmann et al. 2015)</xref>
          . In
addition to domain specific entities, common-sense
knowledge also includes verb usages, reasoning tasks, and rules
that are collected from Systems Engineers, Handbooks, and
the Web (limited).
        </p>
      </sec>
    </sec>
    <sec id="sec-4">
      <title>SYSTEM CONCEPT</title>
      <p>Based on the defined operations concept, primary functional
requirements are derived - ability to 1) Ingest information as
text, 2) Store information in an ontology, 3) Perform
reasoning on the ontology, 4) Respond to interactive queries, 5)
Enter hypothetical mode, 6) Understand time and schedule, 7)
Manage a Dynamic Ontology, 8) Save specific interactions
as ‘Experience’, 9) Connect knowledge base with endowed
models outside the system.</p>
      <p>Requirements 1-8 will be described along with
experiments in the upcoming sections. 9 is outside the scope of
this paper, and for this purpose, we define three generic
components: 1) Monitor, 2) Logicker, and 3) Inter-Module
Communication Protocol. ‘Monitor’ encompasses
methodologies that can oversee, monitor, and assist in debugging
the rest of the architecture. It acts as the central link between
the system and the endowed models located outside.
Architectural components for SEVA are depicted in Figure 2.</p>
      <p>Inter-module Communication Protocol (ICP) in Figure 2
depicts the underlying API (Application Program Interface),
the methodology by which each module will communicate
with one another. For example, it addresses the type and the
format in which the NLP module should produce output in
order to pass it to the ontology module.</p>
      <p>The endowed models represent knowledge that are not
innate to SEVA. The design does not aim to include all
possible knowledge but rather to have the ability to access any
outside knowledge when needed. Monitor encompasses a
special component called ‘Logicker’ that makes this
knowledge transfer possible. This means that SEVA may not know
how to solve ‘orbital mechanics’ or ‘flight dynamics’
problems until 1) an experience occurs, 2) the user teaches it or
3) it endows the knowledge base with an orbital mechanics
or flight dynamics module through Logicker. It is key to
separate such functionalities from essential capabilities such as
elementary math functions (arithmetic, logic, or relational
operations) which will be included in SEVA’s fundamental
capability.</p>
      <p>The architecture based on the aforementioned functional
requirements is shown in Figure 1. Individual components
and experiments will be described in the following sections.</p>
      <p>NATURAL LANGUAGE PROCESSING
(NLP Module)
The NLP module converts raw text into information that can
be represented in the form of an ontology. The NLP
functions are divided into 4 tasks: 1) analyze the linguistic
structure of the domain, 2) extract entities and relations, 3) extract
contextual rules, and 4) interact with the ontology to perform
entity linking and verb normalization.</p>
      <p>
        Triple extraction or relation extraction is a well known
AI technique to populate knowledge bases. In recent years,
Open Information Extraction (Open IE) has received
significant attention as compared to traditional IE systems due
to the ability to extract domain independent triples on a
large scale. In addition, extractions are learned by using
hand-crafted rules or automatically created training data
without using any annotated treebanks. Extractors such as
AI2 Open IE or Open IE 4.x
        <xref ref-type="bibr" rid="ref16">(Etzioni et al. 2011)</xref>
        ,
Stanford Open IE
        <xref ref-type="bibr" rid="ref3">(Angeli, Premkumar, and Manning 2015)</xref>
        , and
ClausIE
        <xref ref-type="bibr" rid="ref11 ref14">(Del Corro and Gemulla 2013)</xref>
        have shown
significant progress in Open IE research and quality in their
extractions. Open IE is particularly important in extracting
relations for common-sense knowledge bases as shown in
works such as
        <xref ref-type="bibr" rid="ref32 ref34 ref47">(Mishra, Tandon, and Clark 2017)</xref>
        to
perform question-answering on elementary science knowledge
which is a part of Aristo (AI2 Allen Institute for Artificial
Intelligence ), an intelligent system, to perform QA about
science. Our goal is to target it to Systems Engineering domain
and address the challenges. An existing challenge for Open
IE is unavailability of labeled corpus for evaluation which
is addressed in works like
        <xref ref-type="bibr" rid="ref68">(Stanovsky and Dagan 2016)</xref>
        and
(Stanovsky et al. 2018). We create a baseline rule-based
extractor and evaluate our system based on a manually
constructed corpus.
      </p>
      <sec id="sec-4-1">
        <title>Systems Engineering Domain Analysis</title>
        <p>Question-Answer Types: QA pairs are collected from
domain experts to understand the type of questions and
answers that matter for individual systems engineers
throughout a mission’s life cycle. For an elementary knowledge
represented as a [subject-predicate-object] triple, we categorize
questions as follows:
1. [S-P-?]: [subject-predicate-?] questions that are looking
for objects in sentences. Example: ‘What is the mass of
STI?’
2. [S-?-O]: [subject-?-object] questions that have Yes/No
answers showing whether there exists the given predicate
link between the subject and the object. Example: ‘Is STI
an instrument?’
Refer to Table 2 to see sample SE questions about SEVA
Testing Instrument (STI).</p>
        <p>Assumptions on Grammatical Constructs: We assume
that the SE text is free of grammatical errors and that
engineers converse with the system in grammatically correct
STI, an instrument,
has a 2500 pixel
CCD detector
STI is an
instrument with a TRL
value of 5
STI is scheduled for
acoustic testing on
July 3, 2015 from
2:00PM to 6:00PM.</p>
        <p>Stanford Open IE
(“STI” “has” “2500 pixel
CCD detector”)
incomplete/ missing
information: “STI is an
instrument”
(“STI” “is” “instrument”)
(“STI” “is instrument
with” “TRL value of 5”)
(“instrument” “is with”
“TRL value of 5”)
(“STI” “is instrument
with” “TRL value”)
produced 13 triples
(“STI” “is” “scheduled”)
(“STI” “is scheduled for”
X)
X = various combinations
of remaining sentence</p>
        <p>
          ClausIE
(“STI” “is” “an
instrument”)
(“STI” “has” “a 2500
pixel CCD detector”)
(“STI” “is” “an
instrument with a TRL value of
5”)
(“STI” “is” “an
instrument”)
(“STI” “is scheduled”
“for acoustic testing on
July 3 2015 from 2:00
PM”)
          <xref ref-type="bibr" rid="ref26">(“STI” “is scheduled”
“for acoustic testing on
July 3 2015 to 6:00 PM”)</xref>
          (“STI” “is scheduled”
“for acoustic testing on
July 3 2015”)
        </p>
        <p>AI2 Open IE
(STI; has; a 2500 pixel
CCD detector)
(STI; [is]; an instrument)
(STI; has; CCD detector)
(STI; is-a; instrument)
(CCD detector;
property; 2500 pixel)
has(STI; is; an instrument
with a TRL value of 5)
(STI; is an instrument
with; a TRL value)
(STI; is; instrument)
(instrument; has-property;
TRL value)
(TRL value; has-value; 5)
(STI; is scheduled; for
acoustic testing)
incomplete/ missing
information: “on July 3, 2015
from 2:00PM to 6:00PM”
(STI; is; scheduled)
(scheduled; for; testing)
(testing; has-property;
acoustic)
(testing; has-value; 3 2015
July)
(scheduled; from; 2:00
PM)
(scheduled; to; 6:00 PM)]
English. We analyze the grammatical constructs of SE text
from the handbook (2017) and domain expert. We expect
that engineering manuals, in general, are less likely to use
pronouns such as I, YOU, HE, SHE, WE, YOU, WHO, and
their object pronouns. However, pronouns such as IT, ITS,
THERE, THAT, THEY, THESE, THOSE, ONE, ONES,
ITSELF, WHAT, and WHICH are prevalent. Coreference
resolution, associating these pronouns to its subject/object, is an
essential task of the NLP module. However, we do not
address this task in the evaluation and is left as future work. In
a sentence, we focus on nouns, verbs, adjectives, and
adverbials to study the phrase structure of the SE text. Our
evaluation consists of only simple independent sentences in SE
domain.</p>
      </sec>
      <sec id="sec-4-2">
        <title>SEVA-TOIE</title>
        <p>SEVA Targeted Open Information Extractor (TOIE) extracts
simple essential relations from SE Text. A Systems
Engineer was tasked with constructing a set of project specific
sentences. The context in which these sentences are
produced are instrument descriptions and instrument
development meetings. Compound sentences are broken down and
complex sentences are excluded. Our data set includes only
independent sentences that do not require co-reference
resolution. A snippet is shown in Table 3.</p>
      </sec>
      <sec id="sec-4-3">
        <title>Sample Sentences in the Data Set</title>
        <p>STI is SEVA Test Instrument. STI, an instrument, has a
2500 pixel CCD detector. STI has a length of 200 cm. STI
is an instrument with a TRL value of 5. The spacecraft
shall provide a direct Earth entry capability for 11500
m/s. The system shall have a 1.4 factor of safety. STI
is scheduled for acoustic testing on July 3, 2015 from
2:00PM to 6:00PM.</p>
        <p>
          The relations extracted are of type: fis a, transitive
verb, has property, has valueg. This is implemented
by pattern matching on the dependency tree produced by
the Stanford dependency parser, phrase chunking, and
occasionally splitting at prepositions. Apart from subjects
(nsubj) and objects (dobj), the algorithm primarily focuses
on a subset of universal dependencies: case, nmod,
compound, amod
          <xref ref-type="bibr" rid="ref13">(De Marneffe and Manning 2008)</xref>
          . The
implementation uses NLTK
          <xref ref-type="bibr" rid="ref56 ref6">(Bird, Klein, and Loper 2009)</xref>
          ,
Stanford Core NLP
          <xref ref-type="bibr" rid="ref40 ref9">(Manning et al. 2014)</xref>
          , and Stanford
POS Tagger(Toutanova et al. 2003). The results from the
base line model are used to evaluate powerful
state-ofthe-art OpenIE systems such as Open IE Standalone by
AI2
          <xref ref-type="bibr" rid="ref43">(Michael Schmitz 2017)</xref>
          , Stanford Open IE
          <xref ref-type="bibr" rid="ref3">(Angeli,
Premkumar, and Manning 2015)</xref>
          , and ClausIE
          <xref ref-type="bibr" rid="ref11 ref14">(Corro and
Gemulla 2013)</xref>
          . A Systems Engineer performed the
evaluation based on three criteria: meaningfulness, completeness,
and minimality of the extracted triples.
        </p>
        <p>
          Basic dependencies produced by Stanford CoreNLP
          <xref ref-type="bibr" rid="ref40 ref9">(Manning et al. 2014)</xref>
          for the sentence “STI, a
satellite, has a 2500 pixel CCD detector” is shown in
Figure 3. Pattern matching based on the dependency tree
triples with the help of noun/verb phrase chunking
produces SEVA-TOIE triples [(STI; has; CCD detector), (STI;
is-a; satellite), (CCD detector; has-property; 2500 pixel)]
that are granular enough to populate SEVA’s knowledge
base. The ‘appos’ dependency defines the subject ‘STI’
producing the “is-a” relationship. The object “detector”
accompanied with compound modifier nouns and the
cardinal number are broken down accordingly to produce the
“has-property” triple. “is-a” relationship is produced from
cop and appos. [S-P-O] triple is produced from
nsubjVerbPhrase-dobj pattern. Both has-property and has-value
relations are produced from amod and nmod-case. S-P
triple is produced from nsubj/NN - CD pattern. Compound
words can be both split and joined accordingly to make
the triple granular using compound/nmod/CD. Noun and
verb phrases can be extracted using simple chunkers such
as N P : &lt; DT &gt;? &lt; J J: &gt; (&lt; N N: &gt; + &lt; IN &gt;)?
&lt; N N: &gt; + and V P : &lt; V B: &gt; +(&lt; : &gt;?(&lt; IN &gt; j
&lt; V BG &gt;))? &lt; T O &gt;? &lt; V B: &gt;
        </p>
        <p>Results &amp; Research Challenge: Although powerful for
large scale extractions, Table 1 shows that the extractions
produced by the state-of-the-art systems can be noisy,
incomplete, and need to be granularized in order to be put
to practical knowledge base construction. Stanford Open IE
uses distant supervision to train a classifier that generate
clauses and uses hand-crafted patterns to produce triples.
The extractor performed well at breaking down triples but
sometimes produced triples in large quantities including
noisy and incomplete ones. ClausIE uses hand-crafted rules
for both clause generation and clause-type detection. The
extractor often produced correct results. However, minimality
of triples was the biggest concern. Open IE 4.x uses
bootstrapping approach and training data to learn patterns. This
system maintained a good balance between the number of
extractions, minimality, correctness, and completeness. The
task identified for future research is to extract high accuracy
targeted triples on a large scale that are granular enough to
be used to populate a knowledge base using the SE in the
loop. This will make use the existing systems in addition to
SEVA’s internal extraction methodology.</p>
        <p>
          Open IE can be customized to the SE domain by
identifying the linguistic structure of the domain language which
can be accompanied by tasks such as parts-of-speech
tagging and semantic role labeling. A sentence represented
using a constituency parser, such as
          <xref ref-type="bibr" rid="ref75">(Zhu et al. 2013)</xref>
          , can
be used to extract sub-phrases from sentences or a
dependency parser, such as Stanford Neural-network parser
          <xref ref-type="bibr" rid="ref40 ref57 ref9">(Chen
and Manning 2014)</xref>
          , can be used to see the relation between
words. A semi-supervised grammar induction can be used to
address domain specific idioms, common-sense knowledge,
and abbreviations.
          <xref ref-type="bibr" rid="ref33">(Klein 2005)</xref>
          and
          <xref ref-type="bibr" rid="ref67">(Spitkovsky 2013)</xref>
          are
some relevant research that address unsupervised parsing
and grammar induction.
        </p>
      </sec>
      <sec id="sec-4-4">
        <title>Types of Input</title>
        <p>We define three types of input informantion that is
represented by SEVA’s knowledge base: 1. Project Specific
Knowledge, 2. Common-Sense knowledge, and 3.
Relational knowledge. Project specific knowledge comes from
the engineer, meetings, and project documents.
CommonSense knowledge comes from the SE Handbook and other
trusted sources. Relational knowledge consists of relational
phrases, verbs, and their axiomatic relationships. This is
closely connected to the ABox, TBox, and RBox knowledge
population which will be described in the ontology section.
Various sources of knowledge in SEVA are shown Figure 4.</p>
      </sec>
      <sec id="sec-4-5">
        <title>Verbs, Vocabulary, and Relations</title>
        <p>
          For successful ontological reasoning, the relations and the
axioms in the ontology need to be well defined. For
example, automatically constructing axiomatic relationships
such as inverse-of (eg: partOf hasComponent )
requires semantic understanding of words and phrases.
Currently, these axiomatic relationships are constructed
manually in the ontology. In this context, our future work will
focus on using WordNet
          <xref ref-type="bibr" rid="ref45">(Miller 1995)</xref>
          for synonyms and
vector models for word and phrase representation such as
Word2Vec
          <xref ref-type="bibr" rid="ref44">(Mikolov et al. 2013)</xref>
          to extract deeper
understanding of relational phrases, their synonyms, antonyms,
and other common-sense domain specific semantic
relationships.
        </p>
      </sec>
      <sec id="sec-4-6">
        <title>Rule Extraction</title>
        <p>
          Extracting rules in desirable forms such as horn clauses
or description logic from text or triples is another
essential NLP task for Ontological reasoning. Currently, rules
are added manually using Semantic Web Rule Language
(SWRL)
          <xref ref-type="bibr" rid="ref28">(Horrocks et al. 2004)</xref>
          to SEVA’s OWL ontology.
Our goal is to assemble the grammatical structure from
parsing, concepts, and relationships into clauses or rule-like
structure. Some relations in the knowledge base need to be
more restricted and better formulated as rules. Rules also
fit better for Closed-World Assumption scenarios. Logic
extraction from text requires unsupervised deep semantic
parsing mentioned in works such as
          <xref ref-type="bibr" rid="ref31 ref35 ref56">(Poon and
Domingos 2009; Schoenmackers et al. 2010; Jha and
FineganDollak 2011)</xref>
          . Example Text: Aerogel can capture a niacin
molecule that has speed less than 5m/s. A rule that is
ideally extracted from the given text: hasSpeed(X; Y ) ^
(Y &lt; 5m=s) ^ N iacinM olecule(X) ^ Aerogel(Z) )
canCapture(Z; X)
        </p>
        <p>Assertion Box (ABox) Terminology Box (TBox)
Spacecraft(DiscoveryShuttle) Conduit Pipe
implies that “Discovery Shuttle is an implies “same-as” relationship
instance of Spacecraft” MassSpectrometer v Spectrometer
partOf(StarTracker, DiscoveryShut- implies “sub-class” relationship
tle))
implies that “StarTracker is a part of
Discovery Shuttle”</p>
        <p>Relational Box (RBox)
partOf partOf v partOf
represents transitive property of the
role
partOf hasComponent
represents inverse property of two
roles</p>
      </sec>
      <sec id="sec-4-7">
        <title>Time Information</title>
        <p>
          SEVA gives special consideration for time entities as they
are significant in scheduling and maintaining a dynamic
knowledge base with temporal reasoning. The result of
passing the sentences “STI is scheduled for acoustic testing on
July 3, 2015 from 2:00PM to 6:00PM. The instrument is
scheduled for vibration testing on July 3, 2015 at 4:30PM
for 3 hours.” to the off-the-shelf 7-class Stanford Named
Entity Tagger
          <xref ref-type="bibr" rid="ref70">(Surdeanu et al. 2011)</xref>
          produces time and date
tags shown in Figure 5. However, it failed to tag “2:00PM”
and “6:00PM”. In addition, ”3 hours” also need to be
semantically understood in context. Both supervised or
unsupervised approaches to construct a model that is trained on
the SE text to detect various time entities are proposed. This
includes making use of the Stanford NER to improve its
results in tagging time entities in the SE domain.
        </p>
        <p>KNOWLEDGE BASE (ONTOLOGY Module)
With the help of the NLP module, the ontology module links
the subjects and objects identified to the concepts and
instances already present in the ontology. Relations are
created by normalizing the verbs to its root form. For our
baseline, we choose a Semantic Web based approach to building
SEVA’s ontology. This provides extensibility and access to
vast knowledge of information. Usage of resources such as
DBpedia will be replaced with a SE specific common-sense
ontology in the future.</p>
        <p>
          Semantic Web and Web Ontology Language
(OWL)
The idea of semantic web framework is to establish a
common representation of data on the web that can be used
universally. SEVA uses OWL 2’s built-in set of specifications
called Resource Description Framework (RDF)
          <xref ref-type="bibr" rid="ref34 ref61">(Klyne and
Carroll 2003)</xref>
          ; essentially a set of RDF triples. The
knowledge representation language is Description Logic (DL), a
decidable fragment of First-Order Logic, and rules which
corresponds to OWL 2 DL and OWL 2 RL
          <xref ref-type="bibr" rid="ref48">(Motik et al.
2009)</xref>
          respectively. Description Logic
          <xref ref-type="bibr" rid="ref37">(Kro¨tzsch, Simancik,
and Horrocks 2012)</xref>
          provides the formal semantics for
designing ontologies in OWL. DLs consist of concepts, roles,
and individuals. Ontological axioms define the
expressiveness and the types of knowledge it can represent. SEVA’s
design uses a popular expressive fragment of DL called SROIQ
          <xref ref-type="bibr" rid="ref12 ref29 ref72">(Horrocks, Kutz, and Sattler 2006)</xref>
          ontology as it fits the
types of knowledge SEVA likes to store and reason from in
its knowledge base. An snippet of SEVA’s knowledge base
is shown in Table 4.
        </p>
        <p>Knowledge created in the ABox is instantiations of
concepts in the TBox or relations between already constructed
instances. This is typically received from project specific
documents. On the other hand, TBox consists of concepts
and their relationships. This knowledge is received from
both project specific documents as well as guidelines, SE
Handbook, and common-sense knowledge. RBox focuses
on axiomatic relationships between relations and is
responsible for ontological reasoning along with is-a relationships.
This information cannot be found in documents and need
to be constructed automatically or manually. This
verboriented knowledge is considered common-sense
knowledge which is constructed specifically for the SE domain.</p>
      </sec>
      <sec id="sec-4-8">
        <title>Knowledge Representation Example</title>
        <p>Next, we describe a representation example that shows the
complexity of our knowledge base construction and
population process. Consider a seemingly simple example “STI has
high angular resolution”. SEVA-TOIE produces two triples
[(‘STI’, ‘has’, ‘angular resolution’), (‘angular resolution’,
‘has-property’, ‘high’)].</p>
        <p>
          Knowledge Base Construction: This phase gives context
by constructing the TBox concepts and relations, and
necessary instantiations in the ABox. This needs to be performed
prior to passing the aforementioned example sentence. The
knowledge “STI is an instrument” or Instrument(STI) must
pre-exist along with the concept of “angular resolution”
such that the entities can be linked.
Knowledge Base Population: This phase populates the
ABox. When there are only predefined named entities and
relations in the TBox, this step can be generally replaced
by the methodologies of Named Entity Recognition
customizing to the domain and Relation Extraction from
templates and by training a model
          <xref ref-type="bibr" rid="ref70">(Surdeanu et al. 2011)</xref>
          .
However, Open IE extracts triples with no pre-specified
templates or vocabulary from arbitrary text. Refer to Figure 6
which shows the snippet of ontology structure for the
example sentence. A sample OWL Ontology constructed is
shown in Figure 7 using Protege OntoGraf visualizer.
          <xref ref-type="bibr" rid="ref17 ref50">(Noy
et al. 2003; Falconer 2010)</xref>
          . Current implementation
considers only a few hand picked structures. Our goal is to
automatically, and through human-in-the-loop process, construct
such domain specific and common-sense ontology structures
which will later help in the creation of a dynamic and
explainable knowledge base.
        </p>
      </sec>
      <sec id="sec-4-9">
        <title>Ontology Compartments</title>
        <p>SEVA’s ontology is divided into Base ontology and
Custom ontology. Custom ontology consists of
domain specific concepts and instantiations, mostly
the TBox and ABox axioms. Instrument(STI) and
partOf(MassSpectrometerMS81Z,STI) fall in to
custom ontology. Population of a custom ontology is easily
performed as long as a solid base ontology is available.
This means that if a framework of concepts and relations
is available, their instances and relations can be added
without any ambiguity. Base ontology contains the essential
ingredients or building blocks for a common-sense ontology
upon which a SE can build their customized ontology. It
consists of basic axioms and rules that govern the ontology.
It predominantly describes relationships and properties
of predicates or RBox axioms such as partOf partOf
v partOf representing transitive property or partOf
hasComponent describing inverse relationship. It
also contains the TBox and ABox information that are
common-sense knowledge such as SE guidelines,
synonyms, and abbreviations. Example: Conduit Tube and
isAbbreviationFor(SLS, SpaceLaunchSystem).</p>
        <p>Research Challenge identified for this step is to
automatically construct the base ontology. A challenging aspect of
this step, in order to have an explainable system, is to
define what constitutes the input for the base ontology. Using
the massive information available on the web is neither a
scalable nor a trustable solution. Using the NASA SE
Handbooks is a good first step. However, common-sense science
and math knowledge is assumed which needs to be learned
as a prerequisite. Essentially, we need to scale and define
what common-sense knowledge is for the SE domain and
identify the sources such that the knowledge is complete and
scoped for a personal assistant’s knowledge base.</p>
      </sec>
      <sec id="sec-4-10">
        <title>Dynamic Knowledge</title>
        <p>
          SEs deals with constantly changing information including
project specifications, time, events, and schedule. New
information will need to be added and old information will need
to be updated. Ontology consistency needs to be checked
on each update. Multiple versions of the ontology need to be
maintained in order to perform temporal reasoning,
scheduling, and undo operation. SEVA is designed as a dynamic
work bench for the SE. Guidelines for a dynamic ontology
is presented in works such as
          <xref ref-type="bibr" rid="ref53 ref54 ref73">(Pittet, Nicolle, and Cruz 2012;
Plessers, De Troyer, and Casteleyn 2007)</xref>
          . To aid user
friendliness, SEVA’s design follows that newer information
overrides older conflicting information. SE will be called in the
loop only if the conflicting information contains a Base
ontology entity or if the user has made some pre-existing
specifications. For example, the user is notified only if there
is a conflict in logic or reasoning process but not a mass
update. The dynamic nature is closely associate with the
ability to handle time. Representing time in ontology and
intelligent systems have been studied by works such as
          <xref ref-type="bibr" rid="ref2 ref31 ref35 ref4">(Allen 1991; Batsakis, Stravoskoufos, and Petrakis 2011)</xref>
          .
Research Challenege identified for this step is to construct
a knowledge base that handles dynamic information and can
perform temporal reasoning.
        </p>
        <p>
          Recent developments in Knowledge Graph
Identification research by jointly performing Entity Resolution, Node
Labelling, and Link Prediction while enforcing
ontological constraints in works such as
          <xref ref-type="bibr" rid="ref10 ref57 ref58 ref9">(Pujara and Getoor 2014;
Pujara et al. 2013; Choudhury et al. 2017)</xref>
          using
Probabilistic Soft Logic is another direction for SEVA’s Dynamic
Knowledge Base Construction. These works show the
importance of identifying the facts that may require revision
due to the varying degrees of confidence in the extractions
produced by the Open IE systems.
        </p>
      </sec>
    </sec>
    <sec id="sec-5">
      <title>REASONING ENGINE</title>
      <p>
        The primary function of this module is to perform
inference on the ontology. TBox inferences include subsumption,
consistency, satisfiability, equivalence, and disjoint
checking. Whereas ABox inferences include instance checking
and retrieval
        <xref ref-type="bibr" rid="ref73">(Walton 2007)</xref>
        . SEVA’s design considers
multiple options for reasoners depending on the design choices
for Knowledge Base construction:
      </p>
      <p>The choices can be evaluated only after the dynamic
nature of the knowledge base is addressed. For the baseline
implementation in OWL and Protege, we use off-the-shelf
Pellet reasoner.</p>
      <p>
        Open/Close World Assumption &amp; Explainability
If something is not known to be true, an open-world
assumption (OWA) assumes incomplete information, and thus the
assistant responds with “I don’t know” as the answer, while
a closed-world assumption (CWA) assumes complete
information, thus the assistant responding with “false” as the
answer. Formal definitions of these two assumptions can be
found in
        <xref ref-type="bibr" rid="ref34 ref61">(Russell and Norvig 2003)</xref>
        . OWA is best seen in
large systems such as semantic web where it is not feasible
to incorporate all possible information in the ontology.
However, some predicates are better represented by the CWA.
For example, “is X partOf Y ”? If the user has never
mentioned that “thrusters are part of the spacecraft”, is it
reasonable to assume they are not? This means that SEVA’s
knowledge base should support an open world assumption
in general but certain predicates should also be allowed to
have closed world property. Works such as (Dama´sio et al.
2006) and
        <xref ref-type="bibr" rid="ref35">(Knorr 2011)</xref>
        study this type of integration. Base
ontology in Figure 8 will integrate OWA and CWA to the
predicates. This will in turn impact the choice of reasoning
engines for SEVA as most rule-like knowledge formalisms
supports CWA while Description Logic support OWA.
      </p>
      <p>For every NASA Engineer who deals with mission
critical information, their personal assistant needs to be highly
trustable in its information assimilation task. Completeness
of the knowledge base and the type of assumptions
mentioned above play an important role in explaining how the
assistant came to an answer. Probability of any answer should
be ideally one and the system should be able to show the
reasoning steps by which the answer is obtained.</p>
    </sec>
    <sec id="sec-6">
      <title>QUESTION-ANSWERING</title>
      <p>
        SEVA adopts the knowledge-based paradigm
        <xref ref-type="bibr" rid="ref32 ref34">(Jurafsky and
Martin 2017)</xref>
        for question answering by building a
semantic representation of the question. NLP module is needed
for parsing, extracting relations from the query, or
extracting rules in some form of query language such as SPARQL
        <xref ref-type="bibr" rid="ref73">(Walton 2007)</xref>
        using the same OIE paradigm. An example of
the DL query in the ontology shown in Figure 7 is
[hasAngularResolutionScale value HIGH] producing STI as the
result.
      </p>
      <p>Querying on an ontology link which consists of
SubjectPredicate-Object can be of two forms: a) asking for the
object and b) asking for the predicate. Possible responses with
an Open World assumption can be a) an answer which is
contextually correct according to SEVA, b) a logical
conversation with the user to understand the missing link or
predicate, or c) an interaction or instructions to the user to teach
SEVA about a missing concept.</p>
      <sec id="sec-6-1">
        <title>Capturing Experience</title>
        <p>Capturing Experience is a process by which the assistant
is taught logically how to arrive at the conclusion or can
be viewed as an algorithm being taught to the assistant for
case-based reasoning. It can use an existing algorithm to
solve a similarly appearing problem with the guidance of the
SE. The following scenario represents the “Unknown due to
OWA” answer type where SEVA linguistically understands
the question being asked, however does not poses enough
information to answer it. It then interacts with the user to learn
logic. The conversation between the user and SEVA shows
an example of how an experience is captured into a case.
User: Can Aerogel capture a Niacin molecule moving at
3km=s?
SEVA: “I don’t know”
User: Start a rule.</p>
        <p>SEVA: Enter the necessary conditions.</p>
        <p>User: Depth of Aerogel times density of Aerogel divided
by density of niacin molecule should be greater than 8mm.
Speed of niacin molecule should be less than 5km=s.
SEVA: Rule Saved! No, Aerogel cannot capture a niacin
molecule moving at 3km=s.</p>
        <p>
          Through such an interactive session, SEVA lets user
create custom rules. Creating contextual awareness is done
through identifying structure of queries and applying
casebased reasoning such as in
          <xref ref-type="bibr" rid="ref36">(Kolodner 1992)</xref>
          with the SE’s
assistance at each learning step. For example, from the query
- Can Aerogel capture a Niacin molecule traveling at speed
100m/s?, a model can be extracted and can be applied to a
different but structural similar question Can Titanium
capture an Inositol molecule moving at 2 km/s?. The user is
required in the process to confirm whether SEVA can use the
same logic (or reasoning) to answer the question and also to
teach SEVA about Titanium if needed.
        </p>
        <p>CONCLUSION AND FUTURE WORK
This work introduced SEVA - a vision of a Systems
Engineer’s personal assistant. It described SEVA’s architectural
design - the big picture, motivation, and its technical
plausibility. SEVA is a single-user system designed to assist SEs
in their day-to-day activities. The work designed the
architecture for a framework with specific goals and constraints
within the context of a NASA SE who deals with risk-averse
complex engineering projects. SEVA makes it easier for the
SE to focus on the creative problem solving by taking care of
all the tedious book-keeping and potentially error-prone
information assimilation. SEVA is a trustable and explainable
system with a domain independent SE framework that grows
by human-in-the-loop learning and becomes user-specific or
domain-specific over time. The work discussed how SEVA
performs natural language processing, information
management, reasoning, learning, and question-answering. We
described what SEVA is and what it is not, as well as the tools
with which such an implementation is feasible and the areas
that require further research and development.</p>
        <p>We designed the overall architecture and implemented
a baseline Open Information Extractor and a Knowledge
Base Module for SEVA. Several sub-components are
provided with high-level descriptions including the research
challenges and implementation directions. Detailed
implementation and technical evaluation of these modules are
currently in progress and are left as future work.</p>
        <p>Although SEVA is designed for a SE, the idea is
extensible to all domains where personal assistants (ones
which can grow alongside the user) are needed. Thus,
extending the idea to other domains is a future direction.
Interconnectedness of different domains and different
engineers add complexity to any project. We envision multiple
SEVAs each belonging to a specific engineer filling the gap
of information assimilation and distributed coordination.
Application of assistants in such collaborative settings is
another area of future work.</p>
      </sec>
    </sec>
  </body>
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