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  <front>
    <journal-meta />
    <article-meta>
      <title-group>
        <article-title>CATReS: a Context-Aware Recommender System for Indoor and Outdoor Museums Tours Planning</article-title>
      </title-group>
      <contrib-group>
        <contrib contrib-type="author">
          <string-name>Roberta Capuano</string-name>
          <email>robbycapuano@gmail.com</email>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Henry Muccini</string-name>
          <email>henry.muccini@univaq.it</email>
          <xref ref-type="aff" rid="aff1">1</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Fabrizio Rossi</string-name>
          <email>fabrizio.rossi@univaq.it</email>
          <xref ref-type="aff" rid="aff2">2</xref>
        </contrib>
        <aff id="aff0">
          <label>0</label>
          <institution>Università degli Studi Dell'Aquila</institution>
          ,
          <addr-line>L'Aquila</addr-line>
          ,
          <country country="IT">Italy</country>
        </aff>
        <aff id="aff1">
          <label>1</label>
          <institution>Università degli Studi Dell'Aquila</institution>
          ,
          <addr-line>L'Aquila</addr-line>
          ,
          <country country="IT">Italy</country>
        </aff>
        <aff id="aff2">
          <label>2</label>
          <institution>Università degli Studi Dell'Aquila</institution>
          ,
          <addr-line>L'Aquila</addr-line>
          ,
          <country country="IT">Italy</country>
        </aff>
      </contrib-group>
      <pub-date>
        <year>2019</year>
      </pub-date>
      <abstract>
        <p>Tourism is a rich and growing activity in the world. The digital support of the tourist experience is typically based on Tourist Recommender Systems (TRS). Widely spread TRSs typically recommend the visit of a set of Point of Interests (POIs). Unfortunately, some of these have also proved inappropriate because they do not consider in detail the indoor visit of a POI, such as a museum, which may contain several artworks and may have limited or regulated access. In this paper, we present our ongoing work on a Context-Aware Touristic Recommender System (CATReS). It provides an outdoor recommendation to select POIs suitable for a visit, as well as an indoor recommendation to select the artwork to visit. The overall recommendations are based on contextual information coming from both visitors' profile and the POIs' contextual information (e.g., the waiting time to access the museum, the average time to visit it). Our tour recommendation system is available and is being experimented at the Ufizi Galleries (Florence, Italy).</p>
      </abstract>
    </article-meta>
  </front>
  <body>
    <sec id="sec-1">
      <title>CCS CONCEPTS</title>
      <p>• Software and its engineering → Contextual software
domains; Software implementation planning; • Information
systems → Social recommendation.
Context-aware planners; tourist recommender systems; outdoor
and indoor visit.</p>
    </sec>
    <sec id="sec-2">
      <title>INTRODUCTION</title>
      <p>The World Wide Web provides tourists with huge possibilities to
search for interesting information and planning their activities.
However, the large amount of data available makes it dificult to
decide. Based on that need, Tourist Recommender Systems (TRS)
are ofered by many resources to support tourists in managing
their long, medium and short tours. A TRS can select and filter the
relevant results to the user from a large database of tourist services
including transportation, accommodations, attractions, Point of
Interests (POIs), and even fixed tour package.</p>
      <p>
        Some approaches focus on the concept of context, largely
associated with the delivery of service based on geographical information
and weather conditions [
        <xref ref-type="bibr" rid="ref3">3</xref>
        ]. In [
        <xref ref-type="bibr" rid="ref10">10</xref>
        ] the context is defined as any
information that can be used to characterize the situation of an entity.
An entity is a person, place, or object that is considered relevant to
the interaction between a user and an application including the user
and application themselves. Context-aware applications are systems
that can adapt their operations or behaviors to the current contexts
with or without the explicit intention of the user intervention [
        <xref ref-type="bibr" rid="ref9">9</xref>
        ].
As we will see in the next sections, we have paid attention to user
profile and preferences, and environmental context to respect the
sustainable tourism principles.
      </p>
      <p>The goal of this paper is to introduce CATReS, a Context-Aware
Tourist Recommender System for the indoor and outdoor museum
tour. CATReS, by taking in input both tourists contextual
information (their user profile and preferences, current location, time
availability) as well as cultural POIs contextual information (waiting
time to access the museum, presence of artwork, museum
location), generates a tourist plan at both macro-level (recommending
which museums, among many, to visit in relation to the tourist
time availability and preference, as well as waiting time to access
it) and micro-level (recommending which specific artwork to visit
in a museum).</p>
      <p>Diferently from other approaches, CATReS, when generating a
touristic plan, takes into explicit account cultural POIs contextual
information (together with tourists contextual information), and
generates a recommendation of feasible museums to visit, as well
as the indoor visit plan.</p>
      <p>The remainder of this paper is organized as follows: in Section 2
we briefly discuss the state of the art in tourist recommendation
systems. Section 3 provides our initial work towards the realization
of the CATReS system. Section 4 reports on an application scenario.
Finally, conclusions are provided in Section 5.
2</p>
    </sec>
    <sec id="sec-3">
      <title>THE STATE OF THE ART</title>
      <p>
        In the literature diferent touristic context-aware recommender
system was proposed. Most of them use Orienteering models [
        <xref ref-type="bibr" rid="ref7">7</xref>
        ] to
ifnd paths to be suggested to tourists.
      </p>
      <p>
        In [
        <xref ref-type="bibr" rid="ref4">4</xref>
        ], Authors discuss eCOMPASS, a context-aware mobile
application that uses Time Dependent Team Orienteering Problem with
Time Windows to derive personalized daily tourist itineraries in the
urban area of Berlin (Germany), which comprises 113 attractions
(POIs) and 100 hotels by considering also public transportation
system.
In [
        <xref ref-type="bibr" rid="ref1">1</xref>
        ], Authors proposed a POI-oriented travel route
recommendation system based on IoT technology and smartphones. They
adopted Bluetooth low energy beacons to sense onsite travel
behaviors that imply personal tourist preference. The App constantly
monitors the phone camera and acceleration sensor to record
several onsite travel behaviors of tourists during a touring course.
They request a querying tourist to input a simple user profile and
personal constraints. Finally, they use a route ranking to retrieve
and rank the candidate travel route for the querying tourist.
In [
        <xref ref-type="bibr" rid="ref5">5</xref>
        ], Scenic Athens is introduced. This is a context-aware
mobile city guide that provides personalized tour planning services to
tourists visiting Athene (Greece) using Mixed Team Orienteering
Problem with Time Windows solved by an Iterated Local Search
metaheuristic. Diferently from [
        <xref ref-type="bibr" rid="ref4">4</xref>
        ], in this works authors
incorporate also scenic (walking) routes. Scenic Athens ofers a variety of
visual means to display the recommended tours and also provides
directions to move from a POI to the next scheduled attraction.
CityTripPlanner [
        <xref ref-type="bibr" rid="ref11">11</xref>
        ] is a web/mobile city tour planner that covers
76 destinations across all continents. The user is allowed to edit
derived tours, remove unwanted POIs and/or adjust visiting time
scheduled for particular POIs. The start/end locations may be
selected.
      </p>
      <p>
        To match the characteristics of tourism and leisure resources or
attractions with the user needs, TRS uses diferent
recommendation techniques. In [
        <xref ref-type="bibr" rid="ref8">8</xref>
        ] authors classified these techniques in two
categories: classical, related to collaborative filtering and content–
based filtering approach, and nonclassical focusing on personalized,
context-aware and ontology-based approach. They underline how
classical approaches do not satisfy TRS needs. For example,
collaborative filtering (CF) methods alone do not satisfy the tourist needs
because it is nearly impossible to find two people experiencing the
same trip, travel duration, the same transportation mode and so
on. On the other hand, using content-based (CB) methods the
system will suggest to tourists the same kind of monuments, while he
maybe will be more interested in items he did not discover during
the last trip.
3
      </p>
    </sec>
    <sec id="sec-4">
      <title>THE CATRES APPROACH</title>
      <p>CATReS is a Context-Aware Tourist Recommender System for
indoor and outdoor museums’ tour planning. It consists of three main
components: i) the context model, ii) the outdoor recommender
system, and the iii) indoor recommender system.</p>
      <p>The context model supports the definition and specification of
contextual information. The context model takes into explicit
account both visitor’s/tourist’s contextual information, as well as
cultural POIs contextual information.</p>
      <p>The outdoor recommender system, by taking in input the context
model, recommends the cultural POIs that match the visitors’ profile
and time constraints.</p>
      <p>The indoor recommender system suggests the artworks to visit
(in the selected museums) to (again) match the visitors’ preferences
and time constraints.</p>
      <p>Figure 1 graphically summarizes the expected output:
given a set of museums with contextual information, and a visitor
with her user preferences (the context model), CATReS returns a
list of museums to visit (the outdoor recommendation), as well as
the artwork to visit (the indoor recommendation), so to satisfy the
imposed constraints (time for the visit, entry time to museums,
etc.).</p>
      <p>The focus of this paper is on the first two components, that are
currently under deployment.
users (with similar profiles) spent watching the artworks,
and the last concerns the waiting time estimated to enter
into each museum.
• Weather conditions: we consider this information to suggest
indoor/outdoor sites according to weather conditions (e.g.,
avoiding recommending to visit a garden in case of adverse
weather conditions).
3.2</p>
    </sec>
    <sec id="sec-5">
      <title>Outdoor tour recommendation</title>
      <p>
        The outdoor tour recommendation can be formulated as a Tourist
Trip Design Problem (TTDP) [
        <xref ref-type="bibr" rid="ref6">6</xref>
        ]. The optimization model most
frequently used in this area is the Orienteering Problem (OP). Given
an oriented graph with weights on nodes (profits) and arcs (costs),
the OP seeks for a tour that maximizes the total collected profit
while maintaining the travel cost under a given value. OP may be
used to model the simplest version of the TTDP. Instead we used
the Team Orienteering Problem with Time Windows (TOPTW)
that calls for finding diferent paths that maximize the collective
score given a predefined time budget with known crossing times
between the POIs and precise time-slots of a visit on each POI. Thus,
we modeled our problem by a graph in which nodes represent the
POIs and there is an edge for each pair of nodes. Any node (POI)
has associated: a score, the opening and closing time of the POI
(expressed also in terms of time-slots) and the mean visit duration.
Weights on the edges represent the travel time. The TOPTW
formulation showed in [
        <xref ref-type="bibr" rid="ref12">12</xref>
        ] was then modified to consider the average
visit time of the POI by changing the two constraints (26) and (28)
in formulation 5.1 as follows:
sip + ti + ti j − sjp ≤ M(1 − xi jp )
N −1
Õ
i=1
(tiyip +
      </p>
      <p>∀i, j = 1, . . . , N ; ∀p = 1, . . . , P
ti j xi jp ) ≤ TMax ;
∀p = 1, . . . , P</p>
      <p>Finally, we added new constraints to model the user’s manual
selection of POIs, to exclude from the outdoor paths sites in case of
rainy days, and to exclude to visit a POI several times when more
time-slots are available.
4</p>
    </sec>
    <sec id="sec-6">
      <title>CASE STUDY</title>
      <p>The CATReS outdoor recommendations approach is currently under
deployment at the Ufizi Galleries (Italy), a museum complex in
Florence comprising the Ufizi Gallery, the Pitti Palace, and the
Boboli Gardens.</p>
      <p>Those three sites are under the same administrative management
and can be easily reached on foot. The Ufizi Gallery is the main
museum, attracting several thousands of visitors per day. The Pitti
Palace includes four museums: the Treasury of the Grand Dukes,
the Palatine Gallery with the Imperial and Royal Apartments, the
Modern Art Gallery, and the Museum of Costume and Fashion.
Directly behind Pitti Palace are the marvelous Boboli Gardens.</p>
      <p>The ongoing deployment process started in August 2019, uses
the CATReS outdoor tour recommendation with a restricted set of
contextual information including the timeslots, POIs, and Weather
data (the three most right contextual information in Figure 2). By
knowing the available entry time to access Ufizi and Pitti, the
distance between those sites, the total time available for the visits,
as well as the minimum reasonable visit time. In the optimization
model, we considered the following parameters associated to the
three sites: a museum score calculated as the average of user ratings
on Google and Trip Advisor, the estimated time for visiting each site,
and the time windows (timeslot in which the site can be visited).</p>
      <p>Figure 1 shows an example of a resulting path. We assumed that
the tourist buys the ticket at the Ufizi Gallery and that the first
entry timeslot available is at 3:15 pm. The resulting path calculated
by the optimization model implemented, considering the number
of available tickets for the other museums is showed in figure.
5</p>
    </sec>
    <sec id="sec-7">
      <title>CONCLUSIONS</title>
      <p>In this paper we presented CATReS, a Context-Aware Tourist
Recommender System that based on context, tourist preferences, and
profiles, suggests indoor and outdoor tours. So far, we implemented
a part of our model, that is being experimented in the Ufizi Galleries.
We implemented a Team Orienteering Problem with a Time
Windows optimization model that takes into account environmental
context referred to weather conditions and site congestion. Future
work will consider tourist preferences and profiles.</p>
    </sec>
    <sec id="sec-8">
      <title>ACKNOWLEDGMENTS</title>
      <p>The authors would like to thank the Ufizi Gallery that is supporting
this work under the agreement with the University of L’Aquila and
the VASARI PON project.</p>
    </sec>
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