=Paper= {{Paper |id=Vol-1289/kese10-01_submission_1 |storemode=property |title=Pattern-driven Knowledge Systems Engineering |pdfUrl=https://ceur-ws.org/Vol-1289/kese10-01_submission_1.pdf |volume=Vol-1289 }} ==Pattern-driven Knowledge Systems Engineering== https://ceur-ws.org/Vol-1289/kese10-01_submission_1.pdf
Pattern-driven Knowledge Systems Engineering

                        Martina Freiberg and Frank Puppe

Department of Artificial Intelligence and Applied Informatics, Institute of Computer
   Science, University of Würzburg, Am Hubland, D-97074 Würzburg, Germany
                 freiberg/puppe@informatik.uni-wuerzburg.de



      Abstract. Despite increasing relevance in research- and industrial con-
      texts, the implementation of knowledge-based systems (KBS) still is
      a challenging task. We motivate, that patterns—basically a renowned
      means for providing reusable solutions for similar problems—can drasti-
      cally leverage development efforts and time. In this paper, we propose a
      framework for pattern-driven, encompassing KBS development, consist-
      ing of: Tailored usability criteria for a clear delimitation of KBS solutions,
      a basic pattern specification template, and a collection of foundational
      KBS UI patterns. We further describe practical experiences with the ap-
      proach, entailing: The reference implementation of several patterns with
      the tailored development tool ProKEt, their design- and usability-related
      evaluation, and empirical evidence of applying pattern-driven KBS de-
      velopment in actual projects.


1   Introduction

Despite increasing relevance in research- and industrial contexts, knowledge-
based systems (KBS) engineering still denotes a challenging task. In general
software engineering, patterns are renowned for describing proven solutions and
preventing common pitfalls, thus fostering reuse and strongly leveraging overall
development efforts. To date, various pattern collections for general UI- and
interaction design are proposed, including [7, 8, 9]; also, many resources are
available freely on the web.
    In contrast to standard web pages or query forms, KBS do not solely build on
strictly predefined question sequences; rather, they characteristically live from
follow-up items—flexibly included interview items that become relevant only
during the questioning session and based on the concrete user input. Also, KBS
often require the prominent integration of additional information for elaborating
the knowledge base / interview items more clearly and of (in-place) explanations
of the results. This calls for tailored UI and interaction solutions that best sup-
port those requirements.
    We motivate, that also KBS engineering can strongly profit from fitted pat-
terns that subsume such proven (and optimally evaluated) KBS solutions; this
can strongly support and refine requirements engineering, and leverage encom-
passing KBS development. First steps into that direction have been already taken
with regards to the knowledge base, e.g., [6]. As counterpart, we propose tailored
patterns, that capture foundational KBS interaction and UI design solutions re-
garding various contexts and target objectives; to the best of our knowledge, no
similar efforts have been published so far.
    The rest of the paper is organized as follows: In Section 2, we introduce a
basic KBS pattern specification framework: A short definition of relevant terms,
tailored (usability-related) classification criteria, and a KBS UI pattern specifi-
cation template. A collection of four framing patterns, that can be fine-tuned
into a total of ten pattern variants, is proposed in Section 3. Practical experi-
ences related to pattern-driven KBS development are reported in Section 4, and
a summarizing conclusion and promising future work are presented in Section 5.


2     KBS UI Pattern Specification Framework

Before proposing a set of usability-related KBS delimitation criteria in Sec-
tion 2.1 and sketching a basic pattern specification template in Section 2.2,
we clarify some basic terms used in the remaining paper.
    Forward- & backward progression: Forward progression starts with an
empty solution set; from one or more init questions, such a KBS then ques-
tions in all directions, depending on the particularly implemented indication
mechanisms. In contrast, a backward progression KBS is initialized with a target
solution and poses only those questions that contribute to the final state of that
chosen solution.
    Multiplex consultation- & clarification KBS: Multiplex consultation
KBS use forward progression, whereas clarification KBS base on backward pro-
gression. Clarification KBS can further be used with two application focuses:
Consultation focussed—i.e., the clarification KBS is started empty, and all con-
tributing questions are posed. Or justification focussed—then, such a system is
called for justifying a solution that already has been derived in the preceding
session, thus corresponding to an elaborate, interactive solution explanation.


2.1   Tailored, Usability-related KBS Classification Criteria

Today, diverse UI design- and usability guidelines and standards are available,
such as Nielsen’s heuristics [5] or the universal design guidelines of Lidwell [4].
However, those typically are defined rather generally as to be applicable for
diverse interactive software system types. Due to their specifics as mentioned
in the introduction, KBS require more tailored criteria; those then can be used
for clearly delimitating their specific characteristics—as, e.g., for the pattern
specification in this work—or for rating KBS solutions regarding their quality
and usability. We propose eight tailored, usability-related classification criteria
as follows:
    1. Compactness: How many interview items are presented simultaneously?
    2. Comprehensibility: Is support provided for understanding specialist,
complex, or ambiguous knowledge base contents (additional explanations, sur-
rounding, contextual questions), and in learning something about the domain?
    3. Descriptiveness: Does the KBS suggest how respective questions/answers
influence the final result of the session, e.g., by indicating the score (change)?
    4. Efficiency: How long does a characteristic session take and how many
interview items need to be processed?
    5. Explorability (Participation): Are users enabled to deviate from the
suggested questioning sequence, are potential expert shortcuts provided?
    6. Intuition (usage): Are the applied presentation/interaction forms famil-
iar or otherwise self-descriptive? If not, are particularly novice users supported
(instructions, tutorials, examples)?
    7. Transparency: Is the current state (i.e., state of questions, results, over-
all progress) clearly and comprehensibly mediated at any time?
    8. Clear Arrangement/Aesthetics: Does the overall design exhibit certain
aesthetics, e.g., by using a small number of virtual lines & basic symmetry?

2.2   KBS UI Pattern Specification Template
Table 1 summarizes a basic template for specifying KBS UI patterns in a unified
and clear manner. All variations of a base pattern exhibit some similar charac-
teristics, e.g., the core KBS objective. They vary regarding the specific realiza-
tion of the UI/interaction, the extent of adhering to KBS classification criteria
(see Section 2.1), the target users, knowledge specifics, and the imposed conse-
quences. In the following pattern descriptions, we only provide a summarizing
template item variations that subsumes specifics regarding the UI/interaction
and required knowledge; we further delimitate the differences regarding the clas-
sification criteria and the target users in Table 2; consequences, as well as details
on the example implementations, are omitted here due to space restrictions.


Pattern Section Description
Problem          Specifies the problem, that is solved by this pattern, based on the
Statement        the tailored KBS usability criteria as described in Section 2.1.
Solution         Describes the general (UI and interaction) solution that all variants
                 of this pattern apply, e.g., the characteristic base interaction.
Variations       Variations of the fundamental pattern, differing regarding: The tar-
                 geted user types, the specific UI realization, knowledge specifics, (con-
                 sequences, and example implementation details—not elaborated in
                 this paper).
        Table 1: Basic template for specifying fundamental KBS UI patterns.




3     KBS UI Pattern Collection
We propose four basic KBS UI patterns: Questionnaire, Interview, Clarifier, and
Clarifier Hybrid, along with variants. In earlier research, we already introduced
three basic interaction categories for KBS, see [1]; there, Adaptive Entry maps
to Questionnaire, Guided Entry to Interview, and Autonomous Entry to Clari-
fier. The patterns basically are intended independent from a specific knowledge
representation—in the sense that for the pattern/UI it is irrelevant whether a
rule-base or a covering model derives the solution ratings; however, some pat-
terns are favorable regarding specific knowledge characteristics—e.g., CheckList
Questionnaire requires all questions to be mappable on a fixed answer set; we
included short remarks on such specifics in the variations’ descriptions.

3.1   Questionnaire Pattern
Problem Statement: The KBS should compactly display a greater part of the
KB, offer a highly transparent UI, intuitive usage, and a certain extent of ex-
plorability; comprehensibility, is no key requirement for the core UI itself.

Solution: Questionnaire KBS resemble paper- or web-based questionnaire forms.
Depending on the particular UI style, many to all indicated interview objects
are displayed simultaneously and typically ordered in some form of grid-based
layout. Questionnaire may suggest (visually), but does not necessarily prescribe,
an optimal interrogation sequence and thus fosters explorative usage. A certain
comprehensibility can be achieved by adding auxiliaries—such as informative
popups with additional explanations for interview items. Per default, Question-
naire uses forward progression, c.f., Section 2

Variations: Box-, Daily-, and CheckList Questionnaire.
     a. Box Questionnaire closely adheres to the design of standard question-
naires by using established, familiar question presentation forms—e.g., check-
boxes and radio buttons for choice questions, see Figure 1, I; thereby, each ques-
tion is rendered within a distinct box, resulting in a very regular layout, but
some waste of UI space.
     b. Daily Questionnaire, originally inspired by daily newspapers, realizes
a more flat, juxtaposed presentation style for questions and answers, c.f., Fig-
ure 1, II; therefore, each question along with its answer options is placed in a
line, implying a less regular yet more compact layout than the Box variant.
     c. CheckList Questionnaire mirrors paper-based check lists by repre-
senting answer options by columns that simply are ticked off, see Figure 1, III.
Therefore, all choice questions need to be mappable to a fixed answer set; includ-
ing further types, e.g., numerical questions, is possible, yet best results regarding
efficient interaction and compactness are achieved with choice questions only.

3.2   Interview Base Pattern
Problem Statement: The KBS UI should be highly intuitive and easily com-
prehensible, thus specifically supporting novice users/domain laymen; in turn,
compactness, descriptiveness, efficiency, explorability, as well as UI transparency
can be neglected.
                                                                                 Light diagnosis                       (III)                 Yes      No   -?-
                                                                                 Is the anterior light working?                              X

                                                                                 Is the rear light working?                                           X

                                                                                 Contact between the anterior light and wire?                              X

                                                                                 Contact between the anterior light and dynamo?              X

                                                                                 Is the anterior light optically in good order?              X

                                                                                 Contact between the rear light and wire?
                                               (II)
                                                                                 Contact between the rear light and dynamo?
                                                                                 Is the rear light optically in good order?
                                                                                 Did the light disorder occur regularly?
                                                                                    How often?                                                | ...



                                                                                                                  Flu is derived as established (Score: +120.0) :            X
                                                                                                                                                                     X
                                                                                                                    Shivers == Yes (+50),        Nausea (-5)
                                                                          (I)                                       Fever == Yes (+40),          Fatigue (+10)
                                                                                                                    Started Slowly == Yes (+10),
                                                                                                                                                             (a)
                                                                                                                                                 Sneezing (+20)
                                                                                                                    Lasted long == unknown,
                                                                                                                    Further Symptoms == Sneezing (-20)

                                                                                                              (a)

                                                                                                                                                           Yes (+20) | No (-5) X
                                                                                                                                              Shivers = yes

                                                                                                                                               Fever = yes           Sneezing = yes
                                                                                                              (IV)
                                                                                                                                        P6   Cold (+40)        P5
                                                                                                                                                                     Fatigue = yes
                                                                                                                               Flu (+120)
                                                                                                                                              Started slowly = yes          X
                                                                                                                                        P5                           Yes
                                                                                                                                                                     No
                                                                                                                                             Lasted long = yes
                                                                                                                           (b)




Fig. 1: KBS Patterns—examples 1: Box Questionnaire (I) and Daily Questionnaire (II) as implemented in ProKEt, CheckList Question-
naire (III), and Form Add-on Clarifier (IV) as preliminary sketch.
Solution: Interview imitates human conversations by presenting always a single
question—or a group of related questions—at a time; additional information are
available anytime quickly and easily, e.g., by directly integrating it near to the
corresponding interview object. Interview typically prescribes the interrogation
sequence in a rather fixed manner. The basic lack of transparency can be alle-
viated by integrating auxiliaries such as an interview object history—listing the
already processed interview items—and a progress information display.

Variations: Strict-, Grouped-, and Hierarchical Interview.
    d. Strict Interview displays only a single question at a time together with
its additional information, see Figure 2, I. Thus, optimally, the KB should pro-
vide suitable auxiliary information for each interview item. Further, a sophisti-
cated indication mechanism is advisable for keeping the possible interrogation
paths at solid lengths, especially regarding large KBs.
    e. Grouped Interview sequentially displays groups of (optimally topically
related) questions or single questions; thus, it is a bit more efficient than Strict In-
terview, and offers more explorability, as the particular sequence within question
groups is not prescribed. The UI uses a similar basic frame as Strict Interview,
where Questionnaire variants are used for rendering the groups, c.f., Figure 2, II.
    f. Hierarchical Interview offers an interactively navigable tree UI specifi-
cally for decision tree knowledge, c.f., [6]. Answer options are presented as width-
spanning tree nodes, c.f., Figure 2, III. Clicking on answer nodes induces their
expansion by the answer options of the follow up question. Solutions are rep-
resented by distinct nodes at the final nesting levels; thus, the tree path from
outer nodes to the solution particularly enables users to ’read’ the justification
of a solution from the visual tree structure. Auxiliary information is presented
in a dedicated side panel—either on click or by hovering the nodes.

3.3   Clarifier Base Pattern
Problem Statement: Selected single solutions in highly expertise domains
should be investigated exclusively and in-depth. The KBS UI should be com-
pact, transparent, descriptive, and offer skill-building ability induced by a high
comprehensibility of the contents; users should be enabled to increase efficiency
in contributing their personal knowledge, e.g., for using shortcuts regarding the
interrogation sequence (explorability/participation). Intuitive usage, in contrast,
is no key requirement.

Solution: Clarifier characteristically uses backward knowledge, see Section 2,
for investigating only a single issue at a time. Therefore, Clarifier renders the
target solution and all contributing questions—i.e., that potentially alter the
solution rating in any way—simultaneously and offers means to adapt answers
and thus investigate the consequences on the solution.

Variations: Hierarchical Clarifier and Form Add-on Clarifier.
        (III)
           (III)


                                                                                      Interview History:
                                                           (I)   (I)
                                                                                      Common Route
                                                                                           Year of birth == 1970
                                                                                           Gender == female
                                                                                                                          (II)
                                                                                      Basic Operative Data

                                                                                       Basic Operative Data

                                                                                         Operation Date                               Anaesthesia

                                                                                                    Month          Year                  General
                                                                                                                                         Regional

                                                                                         Operator
                                                                                              Surgeon
                                                  (II)                                        Surgeon-in-training, supervised
                                                                                              Surgeon-in-training, not supervised

                                                                                                                                 8%             Back   Next




          Day




                   (IV)




Fig. 2: KBS Patterns—Examples 2: Strict Interview (I), Hierarchical Interview (III), and Hierarchical Clarifier (IV) as implemented in
ProKEt, Grouped Interview (II) as preliminary sketch.
    g. Hierarchical Clarifier exhibits its strengths optimally with backward
knowledge that is refined over several abstraction levels. It displays question
and answers options within one node of its tree-style UI, see Figure 2, IV. The
topmost node corresponds to the target solution, and is followed by nodes that
correspond to the directly solution-relevant questions. Each question node again
can be followed recursively by further question levels where the children denote a
more fine-granular partition—one or several questions—of its parent. Thus, users
decide whether to answer the more abstract top-level questions; or whether to
implicitly answer them by expanding them and processing the children—child
answers then are propagated recursively back to the parents.
    h. Form Add-on Clarifier adds minimalistic consultation widgets to static
base justification presentation forms, such as finding lists or rule graphs, c.f.,
Figure 1, IV a&b. Clicking the interview objects in the justification automatically
triggers compact (popup) consultation widgets; those contain all answer options
for the respective question, potentially also indicating the value that is added to
the solution. This allows for interactively adapting answers and thus exploring
and clarifying a selected solution based on its general justification view.


3.4   Clarifier Hybrid Pattern

Problem Description: A more intuitively usable and easily comprehensible
UI representation for using clarification knowledge is desired.

Solution: Clarifier Hybrids merge intuitive, comprehensible KBS UIs with back-
ward knowledge for supporting especially also novice or laymen users in using
clarification KBS. Both Questionnaire and Interview patterns are suitable for
using backward knowledge. The base implementation of Clarifier Hybrid then
corresponds to the variants described in Sections 3.1 and 3.2; in contrast to that,
the targeted backward knowledge is processed, which might—depending on the
actually selected UI variant—require some additions to the base UI; for example,
widgets for explicitly navigating the hierarchical refinement levels.

Variations: Clarification Interview and Clarification Questionnaire.


3.5   Pattern Variants—Detailed Delimitation

Table 2 summarizes the fine-grained delimitation of the proposed patterns ac-
cording to the tailored classification criteria, introduced in Section 2.1; the ex-
tent of their realization is rated from low (L) to high (H). Further, correspond-
ing target user characteristics for each pattern are specified by classifying the
domain-expertise and the frequency of usage. Thus, the delimitation table serves
as quick reference which pattern to apply in what context. If, e.g., a KBS solu-
tion is requested that is both highly intuitive usable, and—given the appropriate
knowledge—highly comprehensible, also and especially for first-time users, then
the Strict Interview pattern suits best, c.f., Table 2.
                                                    Questionnaire               Interview                Clarifier         Hybrid




                                            3.1.a


                                                        3.1.b


                                                                3.1.c


                                                                        3.2.d


                                                                                 3.2.e


                                                                                         3.2.f


                                                                                                 3.3.g


                                                                                                             3.3.h


                                                                                                                     3.4


                                                                                                                              3.4
                     compact                M           H       H       L        M       H       H           H       L        M
Usability Criteria



                     comprehensible         M           M       M       H        H       L-M     M-H         M       M-H      M-H
                     descriptive            L           L       L       L        L       L       H           H       L        L
                     efficient              M           H       H       L        M       M       M           L-M     M        L-M
                     explorable             H           H       H       L        L       M-H     H           H       L        H
                     intuitive              H           M       H       H        M       L-M     L           M       M-H      H
                     transparent            H           H       H       M        M       M       H           H       L-M      H
                     clear arranged         H           M       H       L        M       L-M     M           L-M     L        M
Users




                     expertise: laymen       X          X       X       X        X       (X)     /           (X)     X        X
                                 experienced X          X       X       X        X       X       X           X       X        X
                                 expert      (X)        X       X       /        (X)     X       X           X       (X)      X
                     usage:      one-time    X          X       X       X        X       (X)                 (X)     X        X
                                 frequent    X          X       X       (X)      X       X       X           X       (X)      X

Table 2: KBS UI pattern delimitation according to tailored usability-related KBS clas-
sification criteria with extent of their realization—High (H), medium (M), and low
(L)—and further, regarding two user characteristics—expertise, and usage frequency.




4                      Practical, Pattern-Driven KBS Development

Our practical experiences related to KBS UI patterns encompass: Support of
pattern-driven KBS development by the tailored tool ProKEt [3]; a usability as-
sessment of selected pattern reference implementations with ProKEt; and several
current projects where KBS patterns/pattern-driven development was beneficial.


4.1                      ProKEt: Tool Support for Pattern-driven KBS development

We already introduced ProKEt as a tailored KBS engineering tool that specif-
ically supports template-based development in [3]: By realizing the KBS UI
framework through defining highly modular (HTML) templates with varying
complexity, that can recursively be assembled into more comprehensive ones.
That main mechanism still persists, yet the collection of supported templates
and readily available KBS patterns has been extended. Currently supported
are Box- and Daily Questionnaire, along with encompassing options for sim-
ple property-based fine-tuning—e.g., regarding whether to hide non-indicated
items; Strict- and Hierarchical Interview, with an optional interview history and
progress bar; a configurable solution panel display for all those variants; and
Hierarchical Clarifier, with a tailored add-on information display and a specific
solution panel variant.


4.2                      Evaluation of Selected KBS UI Patterns

In early 2014, an encompassing evaluation was conducted regarding ProKEt ref-
erence implementations of the following KBS UI patterns: Box-/Daily Question-
naire, Strict-/Hierarchical Interview, and Hierarchical Clarifier. Therefore, first
an expert evaluation was conducted by 30 HCI students, using heuristic evalu-
ation according to Nielsen [5] and the cognitive walkthrough technique [10]; the
basic goal was to assess the demo implementations regarding their basic quality
and usability. Afterwards, in total 248 computer science students participated in
a more comparative user study, where certain given problem descriptions were
to be solved with each of the tested KBS; there, students were further instructed
to fill in a short questionnaire for collecting some basic unified values—e.g., re-
garding the overall utility of the KBS—and to provide informal feedback.

 Evaluation Item                          Daily    Box     HInterv   SInterv   HClari
 Success Rate = Correctly solved/all cases 88.71   91.53   27.02     20.16     88.31
 Questionnaire Items
 Q1. Overall utility of the system        2.04     1.93    3.63      3.06      2.72
 Q3. Belief in the result’s correctness   1.68     1.76    4.13      3.86      3.03
 Q4. KB quality=content,structure         2.24     2.16    3.73      3.08      2.82
 Q5. Knowledge mediation                  3.79     3.77    3.64      3.18      2.78
 Q6. Perceived ease of use                1.95     1.57    3.30      2.28      3.03
 Q7. Efficiency of the KBS                2.01     1.84    3.45      2.86      2.83
 Q9. Rating of the KBS UI design          3.58     2.60    3.84      2.57      3.12

Table 3: Results of the comparative user study regarding five selected KBS patterns,
ratings from 1 (very good) to 6 (very bad). Not explicitly listed are Q2 which concerned
the acquired solution (mirrored in the success rate), and Q8 (resolution of the screen).




     Table 3 summarizes the questionnaire-based results of the comparative study
(rating scale: 1/very good – 6/very bad). The first major finding is a strong
correlation between KB quality Q4 and each of KB utility Q1 (0.9968), KBS
efficiency Q7 (0.9813), and perceived correctness of the result Q3 (0.9571), cor-
relation coefficient given in parentheses. Further, KB quality Q4 correlates quite
strong with the overall KBS success (0.8325); thus overall, the KB quality can
be assumed one major influencing factor regarding the overall KBS perception.
This in turn explains the bad overall results for both Interview variants, despite
their way more positive rating in the expert usability assessment: Both vari-
ants used a qualitatively rather unfavorable statistical KB—confirmed strongly
also by subjective remarks. Yet, regarding Strict Interview, at least the basic
tendency of the expert assessment—which confirmed a highly intuitive overall
UI/interaction—was confirmed, see Q6 and Q9.
     Box Questionnaire obviously received the best ratings, closely followed by
the Daily variant; along with provided subjective remarks this indicates, that
the more structured presentation of the Box variant was favored over the com-
pact Daily layout, thereby consenting with the basic expert assessment findings.
Apart from underlining this tendency, however, subjective remarks specifically
criticized the more space consuming presentation of Box Questionnaire and the
general lack of structure in Daily; those comments also revealed more approval
for Daily regarding its ease of use, simplicity, and efficiency. Thus, we suspect an
even further increase in the overall rating of Daily in case it is further enhanced
regarding its presentation—including, e.g., a clearer distinction of question and
answer items, a more prominent highlighting of answered items, and providing
overall visual structure by indicating separators between question/answer lines.
    Regarding Hierarchical Clarifier, the ratings may seem improvable; yet, this
KBS addressed a highly complex KB from the domain of protection against un-
lawful dismissal, with an equally comprehensive problem description of the dis-
missal conditions, the correctness of which was to be rated by the KBS. Thus,
an utility value of 2.68 and even the more a success rate of 88.31 % are particu-
larly good results in the given context of a highly expertise domain but domain
laymen users. Especially the descriptive and transparent style of Hierarchical
Clarifier, mirroring the derived question/solution ratings directly in the UI may
have supported that result; it most likely fostered the overall trustworthiness Q3
(compared to the Interview variants).
    As a general important insight it excelled clearly, that the evaluation of a
KBS UI always is inherently coupled with the applied KB and the respective
problem to be solved.

4.3   Case Studies with pattern-driven KBS Development
Pattern-driven development along with the tool ProKEt already proved highly
beneficial in actual projects. First, we noticed a strong support of the require-
ments engineering process. In the Mediastinitis project—where a documentation
KBS for the structured input of operation data is realized, c.f., [3]—the patterns,
and their ProKEt reference implementations, provided a visual and interactive
means for gathering the user requirements more precisely and quickly. Thus, it
was easy to experiment with several Questionnaire variants—two distinct Box
layouts and one Daily layout—and to let the user formulate his requirements
based on practically investigating the ProKEt pattern demos.
    Another advantage is the fostered reuse of KBS solutions. In the EuraHS
project, c.f. also [3], nearly the same constraints and conditions existed as in
Mediastinitis. Thus, it was quickly agreed that a similar KBS solution would
fit best in that case, too. There, the availability of the Questionnaire reference
implementation in ProKEt drastically accelerated the initial setup of a first
functional demo system—which was gradually refined, particularly regarding
the KB, later, yet the project initiation itself was highly accelerated and eased.
    Similarly, in the JuriSearch project, see [2]—aiming at providing clarification
consultation modules for diverse legal topics—we could easily experiment with a
Hierarchical Clarifier and a (preliminary) hybrid Clarification Interview variant
regarding the most suiting solution.

5     Conclusion
In this paper, we motivated the benefits of pattern-driven development in the
context of KBS. For practical support, we proposed a pattern specification frame-
work, based on tailored KBS (usability) criteria and a pattern template, and we
introduced a collection of 10 fundamental KBS UI/interaction patterns. Fur-
ther, we reported practical experiences with the approach: Using the tailored
KBS engineering tool ProKEt for creating reference implementations of the pat-
terns, evaluating five of them regarding their design and usability, and empirical
experiences with pattern-driven KBS development from current projects.
    Despite denoting an exciting approach for leveraging encompassing KBS de-
velopment, there are several aspects worth investigating in the future: First,
the general extension of the tool ProKEt as to entirely support those patterns
that are specified theoretically only so far. Second, a thorough usability- and
design-related base evaluation of the not yet assessed patterns. Third, an in-
depth inquiry of one assumption that has emerged in the conducted study: That
a structural enhancement of Daily Questionnaire may entail even better results
compared to Box Questionnaire. Fourth, follow-up studies for investigating pat-
terns in direct comparison for delimitating core characteristics even clearer—e.g.,
the pure Clarifier variants vs. one or both Clarifier Hybrids. Another goal is the
actual application of further selected patterns in current (and potential future)
projects; e.g., using Clarification Interview as a first-time user alternative for the
Hierarchical Clarifier in the JuriSearch project.

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