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  <front>
    <journal-meta>
      <journal-title-group>
        <journal-title>Sixth International Workshop on Cultures of Participation in the Digital Age: AI for
Humans or Humans for AI? June</journal-title>
      </journal-title-group>
    </journal-meta>
    <article-meta>
      <title-group>
        <article-title>Representable AI: Towards a Unified View of Core Dimensions for a Visual Framework</article-title>
      </title-group>
      <contrib-group>
        <contrib contrib-type="author">
          <string-name>Angela Locoro</string-name>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Paolo Buono</string-name>
          <xref ref-type="aff" rid="aff1">1</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Marco Winckler</string-name>
          <xref ref-type="aff" rid="aff2">2</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Silvia Corchs</string-name>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <aff id="aff0">
          <label>0</label>
          <institution>Dipartimeto di Scienze Teoriche e Applicate, Universitá degli Studi dell'Insubria</institution>
          ,
          <addr-line>Varese</addr-line>
          ,
          <country country="IT">Italy</country>
        </aff>
        <aff id="aff1">
          <label>1</label>
          <institution>Dpartimento di Informatica, Universit degli Studi di Bari Aldo Moro</institution>
          ,
          <addr-line>Bari</addr-line>
          ,
          <country country="IT">Italy</country>
        </aff>
        <aff id="aff2">
          <label>2</label>
          <institution>Université Nice Sophia Antipolys</institution>
          ,
          <addr-line>Sophia Antipolis</addr-line>
          ,
          <country country="FR">France</country>
        </aff>
      </contrib-group>
      <pub-date>
        <year>2022</year>
      </pub-date>
      <volume>7</volume>
      <issue>2022</issue>
      <fpage>0000</fpage>
      <lpage>0002</lpage>
      <abstract>
        <p>Data visualization made of multiple visualization techniques, e.g., dashboards and small multiples, is taking the scene as data, AI algorithms and their analysis are becoming more complex and articulated. However, still too little is said about what are the core dimensions of these interactions that may contribute to characterize visualization techniques orchestration in scenarios where humans and AI work together and communicate through visual languages, and what is the diferential in complexity with respect to single charts interaction. Depending on such dimensions, their level, and their combination, interaction may require a cognitively growing efort. The present study aims at giving a unified view of complex visual frameworks in order to identify the invariants of visualization techniques characterization, and proposes a group of necessary and suficient dimensions emerging when visualization techniques are the focus of the design and may be the focus of interaction between humans and AI. The paper identifies and discusses these dimensions, starting from the literature, and giving a characterization of each of them in terms of constituent levels. The framework may be applied to analysis of a range of data visualization tools and approaches, towards their concrete application to a distributed visual cognition framework where humans-AI interactions will take place.</p>
      </abstract>
      <kwd-group>
        <kwd>eol&gt;visualization techniques</kwd>
        <kwd>multi-chart interaction</kwd>
        <kwd>conceptual framework for distributed cognition</kwd>
        <kwd>visual AI</kwd>
      </kwd-group>
    </article-meta>
  </front>
  <body>
    <sec id="sec-1">
      <title>1. Introduction and Background</title>
      <p>
        A visualization technique refers to a graphical view of data in the form of charts (static like
bar charts and histograms, or interactive like treemaps) allowing users to analyse and visually
explore a dataset, the input and the output of an algorithm or even its intermediate steps. Whilst
the data might work with multiple chart types, it is often recommended to select the one that
ensures a message clear and accurate according to users needs [
        <xref ref-type="bibr" rid="ref1">1</xref>
        ][
        <xref ref-type="bibr" rid="ref2">2</xref>
        ][
        <xref ref-type="bibr" rid="ref3">3</xref>
        ]. And yet, multi-charts
systems (that combine two or more views) have been proved useful to show diversity and
complementary of information visualization techniques [
        <xref ref-type="bibr" rid="ref4">4</xref>
        ]. Indeed, most recent and widely
adopted tools use multi-charts as a means to design online dashboards [
        <xref ref-type="bibr" rid="ref5 ref6">5, 6</xref>
        ], animated views [
        <xref ref-type="bibr" rid="ref7">7</xref>
        ]
and graph exploration [
        <xref ref-type="bibr" rid="ref8">8</xref>
        ]. Nonetheless, envisioning how visualization techniques may act as
the primary communication means between humans and AI is not a simple task. The dangling
question here is: how to systematically describe the dependencies when combining multiple
charts to support this kind of distributed cognition and communication?
      </p>
      <p>
        As we shall see, describing visualization techniques and the orchestration of multi-charts
is a daunting task. To the best of our knowledge, the literature have investigated diverse
aspects that contribute to the orchestration of multi-chart systems (i.e. [
        <xref ref-type="bibr" rid="ref9">9</xref>
        ]) but it still misses a
comprehensive framework showing all the dependencies. In this paper we try to combine all
previous works found in the literature and then we propose a conceptual framework aimed at
support the discussion in the community about the need of methods for describing visualization
techniques and their orchestration.
      </p>
      <p>In the next sections we identify conceptual entities for describing the techniques for
information visualization. Then we identify four invariant dimensions that might help to explore the
dependencies between multi-charts systems and communication through them.</p>
    </sec>
    <sec id="sec-2">
      <title>2. Towards a conceptual framework</title>
      <p>The conceptual framework presented in this paper moves from a first conceptualization of the
interaction of a user with a visualization technique. The entities and relationships involved in
the interaction are shown in Figure 1. The basement level of the figure describes the entities
in a single chart. A user expresses a goal which might be accomplished by a task through
a set of interactions that contribute to the execution of a Viz technique (short name for
visualization technique). The user interaction might also trigger special operations for querying
and processing raw data so that the resulting processed data maps the visualization technique.
The upper layer in Figure 1 shows the orchestration level of multiple visualization techniques.
It is important to notice that all entities continuously co-evolve. Next section, we will focus on
that specific layer of visualization technique/s orchestration.</p>
    </sec>
    <sec id="sec-3">
      <title>3. The Dimensions of the Visual Frameworks</title>
      <p>Four invariants that play a major role for describing the orchestration of multiple visualization
techniques we identified (based on the literature and on our unifying efort). These dimensions
may afect data visualization tools design, their functionalities and limitations, and the rationale
behind many multi-charts problem-solving approaches.</p>
      <sec id="sec-3-1">
        <title>3.1. Composition (Space) Levels</title>
        <p>
          Most works in the literature refers to the disposition of charts along the Space dimension
([
          <xref ref-type="bibr" rid="ref10">10</xref>
          ], [
          <xref ref-type="bibr" rid="ref11">11</xref>
          ], [
          <xref ref-type="bibr" rid="ref12">12</xref>
          ]).
        </p>
        <sec id="sec-3-1-1">
          <title>3.1.1. No composition</title>
          <p>
            Whenever only one visualization technique is exploited, there is no composition at all. Another
example, with more than one visualization technique, is in the “overview + details” case [
            <xref ref-type="bibr" rid="ref13">13</xref>
            ],
like in the Gapminder tool, where no composition facility is provided (even if two – or more –
visualizations are present in the screen, they refer to the same visualization technique but at
different zoom level). The composition can apply according to the other three levels: juxtaposition
of visualization techniques, superimposition and nesting. Each subsequent level may contain
the previous one.
          </p>
        </sec>
        <sec id="sec-3-1-2">
          <title>3.1.2. Juxtaposition</title>
          <p>It occurs when two visualization techniques are placed side by side, in whatever orientation
(high-to-low or left-to-right). In a multi-charts view, there could be juxtaposition of one or
more of these juxtaposed visualization techniques. An example of juxtaposed visualization
techniques are simple dashboards where the layout is composed of side-by-side and
top-tobottom juxtaposed visualization techniques.</p>
        </sec>
        <sec id="sec-3-1-3">
          <title>3.1.3. Superimposition</title>
          <p>
            It occurs when two visualization techniques are (partially) overlapping. In geo-maps
visualization, diferent layers may be superimposed (e.g., the physical layer and the toponymy
layer).
3.1.4. Nesting
Nesting two visualization techniques means to include one visualization technique inside the
layout of a primary visualization technique, in order to extend the range of information included
in one visualization technique with a second visualization technique. Most of the time, nesting
includes superposition of elements of two or more visualization techniques. For example, graph
links may be nested inside a treemap structure, as in [
            <xref ref-type="bibr" rid="ref14">14</xref>
            ]. Nesting could also apply to the
arrangements of elements in a hierarchical layout (see for example [
            <xref ref-type="bibr" rid="ref12">12</xref>
            ]). When multiple charts
are in place, nested visualization techniques may also be juxtaposed in diferent guise.
          </p>
        </sec>
      </sec>
      <sec id="sec-3-2">
        <title>3.2. Synchronization (Time) Levels</title>
        <p>During interaction, visualization techniques may be positioned along the time dimension too.
Depending on the kind of visualization technique and on the layout structure, the
synchronization of views may assume levels of growing complexity.</p>
        <sec id="sec-3-2-1">
          <title>3.2.1. No synchronization</title>
          <p>The basic level is when no synchronization of visualization techniques is present. Typically,
this situation arises when only one visualization technique is present in the layout.</p>
        </sec>
        <sec id="sec-3-2-2">
          <title>3.2.2. Sequential synchronization</title>
          <p>
            Sequential synchronization arises when visualization techniques are visible one after the other
(for example, in a multi-page environment, like the one provided in Tableau Stories or
dashboardto-dashboard drilldowns, like the ones provided in the Kibana environment [
            <xref ref-type="bibr" rid="ref5">5</xref>
            ].
          </p>
        </sec>
        <sec id="sec-3-2-3">
          <title>3.2.3. Parallel Synchronization</title>
          <p>In parallel synchronization, visualization techniques are visible all at a time. This is the typical
configuration of small multiples visualizations or of dashboards layout (like, for example, in
Power BI, Tableau or Kibana environments).</p>
        </sec>
        <sec id="sec-3-2-4">
          <title>3.2.4. Interleaved Synchronization</title>
          <p>
            When visualization techniques are all present and evolving in time, their synchronization
is “interleaved”. This kind of synchronization may be experienced in parallel, and parallel
interleaved visualization techniques may be experienced in sequence, depending on the layout
structure. An example of the first kind is the Gapminder tool [
            <xref ref-type="bibr" rid="ref7">7</xref>
            ], which provides animated time
series where points at diferent time are all present in the same layout.
          </p>
        </sec>
      </sec>
      <sec id="sec-3-3">
        <title>3.3. Coordination (Tool) Levels</title>
        <p>
          In case a composition exists, it must be coordinated , i.e., visualization techniques can change
congruently. For this dimension we adopt a view of coordination as defined in groupware
interaction [
          <xref ref-type="bibr" rid="ref15">15</xref>
          ][
          <xref ref-type="bibr" rid="ref16">16</xref>
          ][
          <xref ref-type="bibr" rid="ref17">17</xref>
          ][
          <xref ref-type="bibr" rid="ref18">18</xref>
          ]. Coordination can be done according to one of the level of coordination
shown in the next paragraphs.
        </p>
        <sec id="sec-3-3-1">
          <title>3.3.1. No coordination</title>
          <p>When there is no coordination, the layout may either contain only one visualization technique or
the composition is arbitrary, i.e., no congruent changes arise. Many tools with no coordination
are available (see for example tools for single charts design or “disconnected” visualization
techniques in dashboard design, i.e., where a change in one visualization techniques does not
imply a change into another visualization technique).</p>
        </sec>
        <sec id="sec-3-3-2">
          <title>3.3.2. Manual coordination</title>
          <p>In manual coordination, two or more visualization techniques are related by a commonly
changing dataset, a commonly changing visual element (e.g., categorical scale) or a common
functional element (e.g., the same filter applied to two visualization techniques). An example
of manual coordination is, for example, Tableau, where filters can be set to select elements in
more than one visualization technique.</p>
        </sec>
        <sec id="sec-3-3-3">
          <title>3.3.3. Coordination on demand</title>
          <p>In coordination on demand, semi automatic functionalities may be activated on diferent
visualization techniques. For example, in the Knime a visual tool for creating data analytics pipelines
[19], components may relate and be updated congruently on demand (as soon as the pipeline is
executed) or may not, depending on the users’ needs and configurations in the system.</p>
        </sec>
        <sec id="sec-3-3-4">
          <title>3.3.4. Automatic Coordination</title>
          <p>Automatic coordination arises when the user control on the coordination of visualization
techniques is only partial or absent. An example of this is Gapminder, which provides a template
layout where visualization techniques are automatically composed and animated through a
timeline, and only the data can be arbitrarily selected by the user (not the visualization and
animation mode).</p>
        </sec>
      </sec>
      <sec id="sec-3-4">
        <title>3.4. Integration (Data) Levels</title>
        <p>Although not in the foreground with respect to the interactions among visualization techniques,
the Integration dimension (data level) included in visualization techniques is present in our
framework. Ranging from “no integration at all” to “combination/merging/ parsing” of multiple
sources, this dimension was still under-explored and under-defined. This is due to the various
complexity in data integration for which many scholars have struggled to find a solution or at
least an agreement. Many attempts made to capture, at least descriptively, this complexity are
available in the literature about data integration 1. We are not exploring further this dimension,
leaving the levels undefined in terms of what is the complexity involved in each of them, but
only mentioning them for completeness and inclusiveness. We may briefly touch here only
the fact that integration of data may become part and parcel of the growing complexity of
visualization techniques design, interaction and evaluation.</p>
        <p>1See, for example, the table schematized in http://www.cs.toronto.edu/~yuana/DI-Complexity.html for an
overview of data integration complexity.
Angela Locoro et al. CEUR Workshop Proceedings
[19] Knime, 2022. URL: https://www.knime.com, (accessed January 2022).</p>
        <p>80</p>
      </sec>
    </sec>
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