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    ABSTUR: An Agent-based Simulator for Tourist Urban Routes

    Iván García-Magariño ⇑

    Department of Computer Science and Engineering of Systems, University of Zaragoza, Escuela Universitaria Politécnica de Teruel, Calle Ciudad Escolar s/n, Teruel 44003, Spain

    a r t i c l e i n f o

     Article history:

    Available online 5 March 2015

    Keywords:

    Agent-oriented software engineering

    Ingenias

    Multi-agent system

    Simulation

    Tourism

    a b s t r a c t

    There are plenty of expert and intelligent systems related to tourism, either for (1) selecting appropriate

    paths, (2) recommending routes or travel packages, (3) simulating certain implications in tourism, or (4)

    virtually immersing tourists. However, to the best of author’s knowledge, none of these works provides asystem that simulates how many tourist people sign up for each tourist route considering the features of 

    some routes and tourists. This article presents an Agent-based Simulator (ABS) that covers this gap of the

    literature and is called Agent-based Simulator for Tourist Urban Routes (ABSTUR). It receives input from a

    set of routes and certain number of tourists with different types, and provides the number of tourist peo-

    ple signed up for each route after the simulation. ABSTUR has been experienced by assisting a group of 

    tourism experts in designing a set of tourist routes in the historic center of Madrid. In this manner,

    experts were able to avoid collections of routes with overcrowded or non-profitable routes. ABSTUR 

    has also proven to be efficient by comparing it with another ABS with the same specifications.

      2015 Elsevier Ltd. All rights reserved.

    1. Introduction

    Nowadays, the popularity of recommender systems of tourist

    routes is increasing, especially the ones installed in mobile devices,

    as Gavalas, Konstantopoulos, Mastakas, and Pantziou (2014) show

    in their analysis. By the same token, the economics of some cities

    are usually influenced by their tourism activity, as indicated by

    the review of   Song, Dwyer, Li, and Cao (2012). Thus, the tourist

    recommender systems can influence in the tourism of certain

    cities, and consequently in their economics.

    The present research is grounded on the assumption that the

    cores of the tourist recommender systems are their underlying sets

    of routes and their attached suitability recommendations for the

    different kinds of tourists. For this reason, this work presents an

    ABS, called ABSTUR, which guides domain experts in the creation

    and distribution process of appropriate tourist route sets. In this

    process, experts can (1) load a set of routes from a file, (2) simulatethe tourist behaviors in this set routes with several parameters, (3)

    observe whether there is any route overcrowded or non-profitable

    according to the people signed up for each route in the simulation,

    (4) repeat the previous steps until the experts select an appropriate

    set of routes, and (5) export the appropriate set of routes to a web

    application publicly available. In this manner, this ABS assists

    experts in determining and distributing appropriate sets of routes,

    preventing these routes from being non-profitable or overcrowded.

    This work belongs to the context of a research project about

    tourist information systems for promoting cultural urban routes,

    with Madrid historic center region as a pilot project, supported

    by the Hergar foundation (see acknowledgments section for

    further details). In this project, tourism experts are committed to

    propose a set of routes that are useful for presenting routes for

    all kinds of tourists. One of the goals of this project is to provide

    a set of routes that distribute the tourists in a balanced way among

    the routes, according to certain numbers of tourists of each type, in

    order to avoid overcrowded routes and non-profitable routes. For

    achieving this goal, the tourism experts require a simulator as

    the one presented in this paper, so that they can properly assess

    the different sets of routes. In particular, this work addresses this

    need by means of an ABS.

    Regarding the similar existing works in the literature, some

    Multi-agent Systems (MASs) perform simulations in different

    aspects of cities, like for example in   Nguyen, Bouju, andEstraillier (2012), but these ABSs are not strictly related to tourism.

    The existing works related to tourism simulations such as  Balbi,

    Giupponi, Perez, and Alberti (2012)   are not aimed at improving

    sets of urban routes as the current work is. The existing 3D tourism

    simulation environments, e.g. (Hsu, 2012), neither address the goal

    of the current work. Thus, to the best of author’s knowledge, the

    presented ABS is novel in its objectives. In other words, ABSTUR 

    is the first ABS that simulates how many people sign up for certain

    tourist routes given the features of routes and tourists. The

    improvements of the current work over the related works are

    further discussed later in this article.

    http://dx.doi.org/10.1016/j.eswa.2015.02.023

    0957-4174/  2015 Elsevier Ltd. All rights reserved.

    ⇑ Tel.: +34 978645348; fax: +34 978618104.

    E-mail address:  [email protected]

    Expert Systems with Applications 42 (2015) 5287–5302

    Contents lists available at   ScienceDirect

    Expert Systems with Applications

    j o u r n a l h o m e p a g e :   w w w . e l s e v i e r . c o m / l o c a t e / e s w a

    http://dx.doi.org/10.1016/j.eswa.2015.02.023mailto:[email protected]://dx.doi.org/10.1016/j.eswa.2015.02.023http://www.sciencedirect.com/science/journal/09574174http://www.elsevier.com/locate/eswahttp://www.elsevier.com/locate/eswahttp://www.sciencedirect.com/science/journal/09574174http://dx.doi.org/10.1016/j.eswa.2015.02.023mailto:[email protected]://dx.doi.org/10.1016/j.eswa.2015.02.023http://-/?-http://-/?-http://-/?-http://-/?-http://crossmark.crossref.org/dialog/?doi=10.1016/j.eswa.2015.02.023&domain=pdfhttp://-/?-

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    ABSTUR has been designed according to the Ingenias methodol-

    ogy (Pavón & Gómez-Sanz, 2003) using the Ingenias modeling

    language. The programming code of ABSTUR uses a framework that

    is aimed at having a high efficiency, which is necessary in sim-

    ulations with large amounts of agents, data and iterations. For

    instance, this framework avoids high time-consuming messages

    through agent platforms such as the Java Agent DEvelopment

    Framework (JADE) platform (Bellifemine, Poggi, & Rimassa,2001), and gathers groups of people with the same behavior.

    ABSTUR includes five main types of tourists, which are singles,

    couples, families with babies, families without babies, and groups

    of friends. Each of these tourist types is represented with a differ-

    ent agent type. In addition, there is a simulator agent that guides

    all the simulation and presents the analysis of the results to the

    user. Furthermore, a route manager agent is in charge of managing

    the access to the different tourist routes.

    As a proof of concept, this article presents the importation

    process for loading routes from files, the execution of a simulation,

    its analysis, and the exportation of a set of routes to a web applica-

    tion. The execution of the simulation represented more than nine

    millions of tourist people, and was performed with 2350 agents

    and 1200 iterations over 32 Madrid routes, with an elapsed time

    around only three seconds. Furthermore, ABSTUR was compared

    to another ABS recently developed with the same specifications

    but without the adaptation framework. The results show that

    ABSTUR is about nine times faster than the other ABS.

    This work enhances our previous work (García-Magariño, 2014)

    in several ways. To begin with, the simulator now incorporates a

    route loader, so that experts can easily introduce route data from

    files, managing and configuring the route sets for simulations.

    This also allows other practitioners to use this application for sets

    of routes in other urban areas. The simulator now takes more infor-

    mation of tourist routes into account such as their start location,

    duration and types, getting this information from a database. The

    experimentation of the simulator has been enhanced, increasing

    the number of agents from 92 to 2350, the number of routes from

    10 to 32, and the number of iterations from 50 to 1200. In addition,the elapsed time is now measured to show the high performance of 

    the presented ABS. The performance of ABSTUR is now compared

    with another ABS with the same specifications in twelve different

    configurations. Furthermore, the current system now allows expert

    domains to easily export a set of routes to a web application, once

    they obtain a relevant set of routes.

    The remaining of this paper is organized as follows: the next

    section presents the related works indicating the improvement of 

    the current work over the literature; Section  3  describes ABSTUR 

    including its definition with Ingenias, the presentation of the adap-

    tation framework for increasing performance, and a description of 

    its simulation tool and web application; Section 4  shows ABSTUR 

    running for simulating the tourists in Madrid routes, presenting

    the Graphical User Interface (GUI) of the simulator and analyzingthe obtained results; Section   4  presents a comparison of perfor-

    mance between ABSTUR and another ABS with the same speci-

    fications; finally, Section 5  mentions the conclusions of this work

    and the future lines of research.

    2. Related works

    The related works have been classified into different categories

    for its presentation. In particular, Section   2.1   introduces some

    expert and intelligent systems related to the current work.

    Section  2.2   discusses existing MASs in tourism alongside some

    recommender systems for tourists. Section   2.3   presents sim-

    ulations that are related with tourism, including the simulationsin 3D environments. Finally, Section   2.4   summarizes all the

    findings in the literature, and discusses the contribution of the cur-

    rent work over the literature.

     2.1. Expert and intelligent systems

    There are many expert and intelligent systems aimed at obtain-

    ing routes or predicting these. For instance,  Nasir, Lim, Nahavandi,

    and Creighton (2014) present an intelligent system for predictingpedestrian routes. They introduce an algorithm that simulates

    how people select a path for getting to a certain location from

    another. Its system mainly focuses on obtaining a short path that

    avoids certain obstacles.   Jovanović, Pamuč ar, and Pejč ić-Tarle

    (2014)   introduce an intelligent system for routing green vehicles

    based on a neural network and a fuzzy approach. This work pre-

    sents a distribution model of vehicles in a public transport net-

    work.   Zhao and Jiang (2015)   apply the Memetic algorithm to

    optimize the routes for reducing the network transit reducing cost

    per passenger. It uses a genetic algorithm for solving this problem.

    All these works are mainly focused on obtaining either the shortest

    paths or the distribution with less transit, assuming each user

    wants to go from one location to another. By contrast, the current

    work is aimed at simulating people signing up for tourist routes, in

    which these people select routes mainly according to their tourism

    preferences.

    There are several works that use MASs for simulating different

    aspects of cities. For instance,   Nguyen et al. (2012)   present an

    ABS that simulates the different kinds of transportation in a city.

    This work takes travel, parking and transportation strategies into

    account. In addition,   Mustapha, Mcheick, and Mellouli (2013)

    simulate natural disaster complex systems with an ABS. Its main

    goal is to guide rescue teams in an effective organization for saving

    as much lives as possible in natural disasters. In this line of 

    research,   Wijerathne, Melgar, Hori, Ichimura, and Tanaka (2013)

    present an ABS for simulating the evacuation of urban areas. In this

    simulation, they show the effectiveness of a navigation algorithm

    that allows a massive number of people to rapidly evacuate from

    a large urban area. Similarly,   Wagner and Agrawal (2014)   havedeveloped an ABS for the evacuation of crowded places such as

    auditoriums and stadiums where there is uncontrolled fire, in

    order to establish the necessary measures beforehand, so that the

    consequences in real fire situations are mitigated. All the afore-

    mentioned works have in common with the current work that they

    use ABSs for simulating scenarios beforehand in order to improve

    the organization or measures when the real situations occur.

    However, none of these works uses ABSs for guiding tourism

    experts for obtaining suitable sets of tourist routes, as this work

    does for promoting urban tourism.

    Lin, Lin, Hu, and Lee (2014)   present a method for generating

    destination maps and thematic maps for tourists to meet their

    mental map. In particular, firstly they apply a network warping

    method. Then, they deform the road network according to theuser-specified mental map. In this manner, their resulting map

    provides visual aids for route planning and navigation tasks for

    tourists, as well as including certain purposes of advertising.

    Thus, this work assists tourists in planning routes with a generated

    map that is similar to mental maps, but it does not provide a sim-

    ulator of tourists signing up for routes as the current work.

     2.2. MASs and recommender systems in tourism

    Some works present MASs for addressing certain goals in tour-

    ism field. For instance, Jung (2011) presents a MAS that constructs

    indirect alignment between ontologies with different languages.

    The MAS was deployed through the JADE platform. By contrast,

    the current work uses the MAS for predicting tourism people selec-tions, for achieving an appropriate set of Madrid routes.

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    Moreover, the Tourist@ system (Batet, Moreno, Sánchez, Isern, &

    Valls, 2012) is an agent-based recommender application for

    suggesting personalized routes to tourists once they have arrived

    to their location. This work takes several features of tourist profiles

    into account. Similarly, the current work includes a web applica-

    tion that also recommends routes for different kinds of tourists.

    Nonetheless, that work does not consider the repercussion of 

    unbalanced sets of tourist routes, as the current work does.Lately, several recommender systems have been proposed for

    recommending tourist routes. In particular,   Borràs, Moreno, and

    Valls (2014) present a survey of most recent recommender systems

    for tourists. It classifies these systems between web-based applica-

    tions and mobile applications. It also reviews systems according to

    their functionalities. These functionalities are (1) to offer travel

    destination and tourist packs, (2) to rank lists of suggested attrac-

    tions, (3) to plan routes customized for each user and (4) to con-

    sider certain social aspects in tourist routes. It also mentions the

    main artificial intelligent techniques that have been applied in this

    field.

    The Gat platform (Rodriguez-Sanchez, Martinez-Romo,

    Borromeo, & Hernandez-Tamames, 2013) provides a mechanism

    for offering a mobile recommender system, by automatic crawling

    points of interests from the web. This automatic process was

    supervised by a human expert, and this platform was experienced

    by obtaining Spanish points of interests from the Wikipedia.

    The Objected-oriented Recommender System (ORS) (Tan, Liu,

    Chen, Xiong, & Wu, 2014) incorporates several types of context

    information for suggesting travel packages to their users. For

    instance, it considers travel area, season and price of travel pack-

    ages. It can also use additional information with feature-value

    pairs. This system either uses (1) extraction of topics based on

    intrinsic feature-value pairs, or (2) a Bayesian network for calculat-

    ing probabilities that a tourist selects the same travel package as

    another previous tourist.

    Moreover,  Liu, Xu, Liao, and Chen (2014)  present a system for

    recommending personalized routes, taking real-time traffic infor-

    mation into account. Their goal is to reduce the time of touristsin traffic jams and queuing, mainly in tourist hot spots. Their

    system receives input from the real-time traffic situation and the

    users preferences, and recommend self-drive routes for their tour-

    ist driver users.

    SigTur/E-Destination (Moreno, Valls, Isern, Marin, & Borràs,

    2013) is a web-based recommender for routes in Tarragona

    (Spain). This system applies an ontological approach for providing

    routes for tourists. In addition,   Garcia, Sebastia, and Onaindia

    (2011)   present a recommender system for tourist routes as an

    extension of the e-Tourism system. Their extended system recom-

    mends routes for not only tourist individuals but also to tourist

    groups, as the current work does. The recommender is experienced

    with routes in the Valencia city (Spain).

    All these recommender systems are mainly focused on provid-ing personalized routes without (1) simulating different kinds of 

    tourists signing up for routes nor (2) providing a tool that assists

    tourist experts in designing balanced sets of routes that avoid over-

    crowded and non-profitable routes, as the current work proposes.

     2.3. Tourism simulators

    There are works that concretely perform simulations related to

    tourism. Specifically,  Balbi et al. (2012)   have constructed an ABS

    for assessing the impact of weather conditions on the alpine tour-

    ism. Their system mainly considers three factors, which are the

    weather conditions (snow cover and temperature), numbers of 

    the different kinds of tourists and the type of market competition.

    In addition, they use eight different kinds of tourist agents. Thiswork is similar to the current one in two factors: (1) both works

    use ABSs in the tourism context (2) both works use similar number

    of tourist profiles. However, there are two main differences. Firstly,

    the tourism environments are different (alpine areas opposed to

    urban areas). Secondly, the improvement objective is quite

    different; the former work is aimed at improving the infrastruc-

    tures from the winter industries point of view, while the latter

    work pursues the improvement of the set of offered tourist routes.

    Moreover,   Hamilton, Maddison, and Tol (2005)  present a sim-ulation that analyzes the influence of international tourism in the

    climate, population and income of different countries. This work

    is based on data of departures and arrivals for 207 countries, and

    concludes that the influence of international tourism is higher in

    population and income than in climate. Nonetheless, the goal of 

    the current work is different, since it is aimed at promoting the

    tourism in particular cities instead of forecasting its international

    influence on different countries.

    McArdle, Furey, Lawlor, and Pozdnoukhov (2014)  introduces a

    simulation of traffic flows in the Greater Dublin region. It receives

    input from the digital footprints of city inhabitants in applications

    such as Twitter and Foursquare. They simulate traffic volumes at

    main road segments at certain travel periods. This information

    could be used by tourists when selecting a self-drive route. In par-

    ticular, they chose MATSim (Multi-agent Transport Simulation

    toolkit) as the agent-based simulation toolkit. However, this works

    is mainly aimed at predicting traffic flows due to citizens, which is

    a different goal from the objective of the current work.

    Furthermore,   Paletta and Herrero (2011)   present a simulating

    collaborative system by means of an ABS. This system includes a

    tool in which users can configure the parameters of each sim-

    ulation. As a case study, they present a simulating collaborative

    system for designing combined traveling packages. The purposes

    of these traveling packages are mainly tourism, business and plea-

    sure. However, these packages are related to the transport and

    accommodation rather than the tourist routes as in the current

    work.

    Some works relate to the simulation of tourism situations with

    3D environments. In the education context,   Hsu (2012) uses theSecond Life 3D virtual environment for making eight students train

    in tourism situations within this environment with considerably

    less cost than training in real scenarios. In the e-Marketplace con-

    text, the work of   Gärtner, Seidel, Froschauer, and Berger (2010)

    provides a mechanism for mapping the gap between software

    agents and 3D environments, for allowing agent-mediated

    e-Marketplace in immersive 3D virtual environments. On the con-

    trary, none of these works is specifically aimed at obtaining an

    appropriate set of tourist routes for a given city, as the current

    work addresses.

     2.4. Discussion

    As one can observe in the previous subsections, there are manyrecent works related to the current one especially in the fields of 

    (1) expert and intelligent systems, (2) MASs and recommender sys-

    tems in tourism, and (3) simulators in tourism. In the first field, one

    can highlights the existence of several route finders considering

    some current location and a desired destination, simulators for

    other city aspects such as evacuation on disasters, and a generator

    of tourist maps. The second field includes a MAS for ontology align-

    ment in tourism, and plenty recommender systems for tourism

    routes, travel packages and self-drive paths for tourists. In the third

    field, there are simulators that simulate either the influence

    between the tourism and the climate, traffic flows, the collab-

    orative creation of combined travel packages, or 3D environments

    for virtually experiencing tourism.

    Nevertheless, in none of these works or any other to the best of author’s knowledge, there is a simulator that simulates how many

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    tourist people sign up for tourist routes based on the features of 

    both routes and tourists. Thus, the current work is the first one that

    proposes this kind of simulator.

    3. ABSTUR: an Agent-based Simulator for Tourist Urban Routes

    The presentation of ABSTUR has been divided into several

    subsections. Section   3.1   introduces the specification of ABSTUR expressed with the Ingenias modeling language. Section  3.2   pre-

    sents the adaptation framework that makes ABSTUR efficient.

    Section 3.3 describes the simulator tool of ABSTUR and its related

    web application.

     3.1. Specification of ABSTUR with Ingenias models

    The definitionof ABSTUR containsthree differentroles and seven

    agent types for allowing users to simulate the tourists choosing

    routes of a particular city. These three roles and seven agent types

    are graphically presented in Fig.1 withthe Ingenias notation, along-

    side the goals of the ABS. It is worth mentioning that this diagram

    uses the -R suffix for roles and the -A suffix for agents, in order to

    avoid conflict of names in an abbreviated way. In order to make this

    diagram and the following ones understandable, the main concepts

    of the Ingenias notations are determined in Fig. 2.

    ABSTUR has the following roles with the corresponding agents:

     Simulator role: the agent playing this role is in charge of con-

    ducting the whole simulation. In particular, the simulator agent

    plays this role. This agent provides a GUI, so that the human

    expert can configure the parameters of the simulation and exe-

    cute it. When the human expert asks this agent to conduct the

    experiment, this agent initializes the remaining agents accord-

    ing to the established parameters, and starts the necessary

    interactions to make the other agents run for the simulation.

     Tourist role: this role gathers all the agent types that represent

    the different kinds of tourists. This role defines the commoninteractions to all the kinds of tourists. These interactions

    mainly concern (1) the search for a trip when the simulator

    agent asks so, and (2) the selection of a route by communicating

    with the route manager agent. The agents of this role represent

    both individual people and groups of people. Thus, each agent

    can represent a different number of people. This role is played

    by the following agent types:

    –   Single tourist agent : this agent represents a single person that

    is interested in visiting the city of the simulation.

    Fig. 1.   The definition of agents with the Ingenias notation.

    Fig. 2.   Main concepts of the Ingenias notation.

    Fig. 3.   Interaction between the simulator agent and the agents playing the Tourist role.

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    –   Couple tourist agent : this agent impersonates a couple that

    plans to travel to the city of the simulation.

    –   Family babies tourist agent : this agent represents a family

    with at least one baby under two years old. The family can

    also have other children of whatever age.

    –   Family tourist agent : this agent conforms a family with at

    least one child, and all the children must be above two years

    old.–   Friends tourist agent : this agent represents a group of several

    friends.

     Route manager role: this role manages the routes of a city. This

    role is the responsible for accessing the routes when an agent

    playing the Tourist role requires so. In addition, the agent play-

    ing the route manager role provides rank recommendations for

    each presented route from one to ten according to the specific

    kind of the particular tourist agent.

    The simulations are triggered by the user through the GUI. Inthese situations, the simulator agent initializes the tourist agents,

    and starts interactions with these. In particular, the interaction

    Fig. 4.   Interaction between the agents playing the Tourist role and the route manager agent.

    Fig. 5.  Excerpt of the adaptation framework.

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    between the simulator role and the Tourist role is determined in

    the diagram of  Fig. 3. In this interaction, the simulator agent sends

    a broadcast message to all the agents playing the Tourist role for

    proposing them to start a trip, by means of the task namedRecommend Tourist Travel.

    Each tourist agent determines the desired features of tourist

    routes with the Start Manager Interaction task. In particular, within

    this task, the agent determines the current position in the city of the tourist group or person that it represents. It also establishes

    the desired type of route. Some possible route types are outdoor

    walking routes, routes with museums, routes with nature, routes

    with art, routes with monasteries, and routes with bicycle. The

    agent also indicates the preferred duration of the route in number

    of hours. Then, each tourist agent will start a negotiation interac-

    tion with the route manager role for obtaining a trip that suits

    its preferences and its type of tourist.

    The negotiation process is performed through the interaction

    between the Tourist role and the route manager role defined in

    Fig. 4. In this negotiation, a tourist agent starts looking for a trip

    in the corresponding task. The tourist agent sends an interaction

    unit (also known as message in other methodologies) with its tour-

    ist type and its preferences. The route manager agent collects all

    the available routes with their information in the system for the

    given city alongside the recommendation ranks of each route for

    the corresponding tourist type. The list of routes is sent back to

    the tourist agent, by means of the  list of routes  frame fact.

    After this, the tourist agent starts the decision-making process

    for selecting a route from the provided list of routes. To begin with,

    it considers the distance between its current location and the start

    point of each route in the city. It assesses the routes that start in

    nearer locations as better. It also considers whether each route

    belongs to its desired type (e.g. outdoor, with museums and so

    on). It also takes the duration of each route into account in compar-

    ison with its desired duration of route. Finally, it also considers the

    generic recommendation of a route, ranked from one (lowest) to

    ten (highest) of a route, for its specific tourist type (e.g. couple,

    family with babies or other). The decision-making of each agent

    assigns more importance to some features than others according

    to the tourist type. For instance, proximity to start point and route

    duration are highly relevant for families with babies. This decision-

    making process assesses all the routes, and selects the route that

    best suits the preferences and type of the corresponding touristagent.

    Then, in the negotiation process, the tourist agent asks the route

    manager to book the route for the given number of people that the

    tourist agent represents, by means of the Sign Up Route   interaction

    unit. If there are any vacancies, the manager agent books the route

    and confirms the operation to the tourist agent. If there are not any

    vacancies, the route manager asks the tourist agent to select

    another route. This negotiation process is repeated until the tourist

    agent requests a route that has vacancies and consequently both

    agents reach an agreement, or until some of the agents stops the

    interaction.

    After the negotiation process, in case of agreement, the tourist

    agent makes note of the booked route, and sends the booking infor-

    mation back to the simulator agent, finishing the other interaction

    between the simulator agent and the tourist agent that was pre-

    viously initiated. In particular, the tourist agent sends (1) basic

    data of the route and (2) the number of people that the tourist

    agent represents. Both pieces of information are transferred by

    means of the Route and NumPeople frame facts.

    The simulator agent collects the data of each tourist agent in theCollect Simulation Data  task. After several rounds of trips, the sim-

    ulator agent extracts the relevant information and presents it to

    the user. The number of rounds of trips is one of the parameters

    established for the simulation in the GUI by the user.

    The complete definition of all the Ingenias diagrams of the ABS

    is omitted in this paper for the sake of brevity. From all the

    Fig. 6.   Excerpt of the particularization of the adaptation framework for tourist routes.

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    corresponding Ingenias diagrams, the programming code was

    generated by means of the Ingenias Development Kit (IDK)(Gomez-Sanz, Fuentes, Pavón, & García-Magariño, 2008).

     3.2. Adaptation framework for extensive tourist simulations

    The programming code was generated for the ABS specified in

    the previous section by means of the Ingenias Agent Framework

    (IAF), which is one of the main IDK plugins. However, due to the

    high number of agents that are necessary in these kinds of sim-

    ulations, this paper presents an adaptation framework to fasten

    the communications between agents. This framework has been

    applied in the presented ABS.

    In particular, an excerpt of the proposed simulation framework

    is presented in   Fig. 5. In this framework, the communications of 

    agents are performed trough Java method calls, instead of usinghigh-consuming messages through the JADE platform. The

    Simulation class contains all the agents within a list. All the agents

    have the live method, in which they perform their activitiesperiodically. The different kinds of agents are represented with

    classes that implement the Agent interface. The communications

    are performed through a blackboard represented with a class. In

    this manner, all the agents can implicitly communicate among

    themselves through the Blackboard class, saving the time and costs

    of explicitly resubmitting the information. All the agents can access

    to the blackboard through the Singleton pattern (Nguyen, 1998),

    which guarantees that there is always a unique object of the

    Blackboard class. The attributes and methods of the Blackboard

    class are defined taking the specific domain into account. In addi-

    tion, the GUI is represented with the MainGUI class. This class has a

    reference to a Simulation object. In fact, the GUI interacts with the

    user, creates the corresponding simulation, and then runs it.

    Finally, it shows the results of the simulation to the user. In fact,this class is recommended to have at least methods for (1) creating

    Fig. 7.   Loading routes successfully.

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    the agents according to the parameters established by the user, (2)

    loading the necessary data from a file indicated by the user, (3)

    performing the simulation with the corresponding agents and

    parameters, (4) showing the results to the user.

    An excerpt of the particularization of the aforementioned sim-

    ulation framework for ABSTUR is shown in Fig. 6. Since all the tour-

    ist agent types have very similar operations except for the tourist

    type that is provided to the route manager agent, a unique classis implemented for all the tourist agents, and this class has an attri-

    bute that specifies the tourist type from an enumeration type. This

    class is called TouristAgent, and also has an attribute for indicating

    the number of people each agent represents.

    The blackboard allows tourist and route manager agents to

    retrieve or establish the information related to the features of each

    routes such as start and finish locations, the duration of the route,

    its type or types, and the recommendation values for each specific

    tourist type.

    The route manager agent is responsible for loading the set of 

    routes from a file, with their identifiers, titles, and recommenda-

    tions for different types of tourist. In this loading, the route man-

    ager agent also loads other information from a MySql database

    for each route by means of its identifier. This information includes

    the initial and final locations of each route, its estimated duration,

    and the type or types of the route (outdoor walking, with

    museums, with monasteries, and so on). Notice that some routes

    can have several types. For instance, there are routes that visit

    museums and also have art (two types) (e.g. a route with the

    Prado museum in Madrid). However, these two types are not the

    same, because there are also routes that visit museums without

    art, and routes with art that do not visit museums. The route man-ager agent saves the information retrieved from the file and the

    database in the blackboard once, and all the later requests from

    the tourist agents access this information from the blackboard. In

    this way, these requests do not need to access again the database

    avoiding consuming time for this, making the simulator efficient.

    Additionally, the route manager agent also loads the information

    of some hotels with their locations and their number of rooms

    from the database, and stores this information in the blackboard

    once.

    After the negotiation processes, the route manager agent

    updates the number of people signed up to each route in the

    blackboard, considering the number of people that are represented

    by a particular tourist agent. Then, when the simulator agent is

    informed that all tourist agents have finished their tourist

    Fig. 8.   Detection of errors in the loading process.

    Fig. 9.   Excerpt of file of routes with errors.

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    simulation by means of interactions, the simulator agent directly

    accesses to the information of people signed up to each route from

    the blackboard, without needing to recount all these information

    from the corresponding interactions with the tourist agents.

    The strategies of tourist agents for selecting routes are imple-

    mented within each tourist agent type. However these strategies

    need information of routes such as the start location, duration

    and types of certain routes previously offered by the route man-ager agent with the corresponding identifiers. Tourist agents can

    directly access to this information of particular routes from the

    blackboard with the identifiers, without wasting time performing

    new interactions with the tourist manager agent, making the sim-

    ulator efficient. In addition, the locations of tourist agents are ini-

    tially established as the locations of some hotels of the city. This

    hotel location is established by asking for an available hotel room

    from the blackboard. Then, after following short routes, the loca-

    tion of a tourist agent is updated as the final location of the

    particular route. After one long route or several short routes, each

    tourist agent is assumed to come back to the hotel.

    Therefore, although the negotiation process is performed

    through interaction between agents, the retrieval of information

    is performed through the blackboard. In particular, the tourist

    and manager agents interchanges identifiers of routes in the

    negotiation, but all the related information of particular routes is

    mainly directly taken from the blackboard by the agent that actu-ally needs this information.

    Moreover, the GUI has the necessary attributes and methods for

    implementing an internal chronometer to measure the elapsed

    time of each simulation. The GUI allows users to export the routes

    to a web application once an appropriate set of routes is achieved.

    For exporting the routes, the WebGenerator class was imple-

    mented. This class generates several files into web format from a

    list of routes. These files can be directed uploaded to a web appli-

    cation, so people can freely access to these routes with the

    Fig. 10.   Results of the simulation.

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    associated recommendations from the web. The web application is

    further described in the next section. The RouteComparator class

    has been added to compare routes regarding the different tourist

    types. The comparator allows the web generator to sort the list

    of routes respectively according to the recommendations for the

    different tourist types.

     3.3. The tourism simulation tool and the web application

    ABSTUR is composed of the ABS tool and the web application.

    The ABS tool allows users to load a set of routes from a file by

    pressing the button titled Load Routes From File in the top-right side

    of its graphical interface, which is shown in Fig. 7. In fact, when this

    button is pressed, the user can browse which file to load from a file

    chooser. After loading the routes, the label just before the bottom

    table changes to   Loaded Routes for the Simulation, as one can

    observe in this figure, and the bottom table displays the loaded

    routes.

    An example of the format of the routes is shown in Appendix A.

    Basically, the first line of the file is used as header, and reminds the

    route designers the format and content of each line to represent aroute. Consequently, the parser ignores this first line. After this,

    each line represents a route with some recommendations for each

    tourist type. Each piece of information is separated by a semicolon,

    and will be referred as an argument from this point forward. The

    first argument contains the identifier of the route, which identifies

    the route so that users can access to all its documentation collected

    by the members of the acknowledged research project. This identi-

    fier also allows the ABS tool to obtain some information of each

    route from a database defined from this documentation of routes.

    The second argument is the name of the route. The next five argu-ments must be numbers that determines the suitability of the

    route for respectively each tourist type, with the following order:

    singles, couples, families without babies, family with babies, and

    groups of friends. The header first line is mainly used to remind

    this order to route designers.

    In some cases, and especially when working with large number

    of routes, designers can make some errors in their files. For this

    reason, the presented tool provides some assistance for fixing the

    files of routes. In particular, if there is any error, the encountered

    errors are mentioned in a message dialog. An example of this mes-

    sage dialog is presented in Fig. 8. The other routes that do not have

    errors are loaded into the tool as one can see in the bottom table of 

    this figure. For each erroneous route, the message indicates its

    identifier and the line number of the route alongside a brief indica-tion of the error kind. In particular, in this example the route with

    identifier CHG3 of line 5 has a wrong number of arguments.  Figs. 9

    shows an excerpt of the file of routes for this example, and one can

    see that this routes has one more argument than required (six

    instead of five numeric recommendations). The other error is

    related to the fact that there is a wrong number format in one of 

    the arguments of route LF1 in line 13. Specifically, in the file one

    can see the e  character instead of a number in the fourth numeric

    recommendation.

    After loading the routes, one can establish certain parameters of 

    the simulation directly in the tool. All these parameters are located

    below the Input of Simulation label. Each parameter must be speci-

    fied in a text field. Each text field is next to a label that indicates the

    required content. In particular, each designer can specify the num-ber of each type of tourist or group per iteration. Hence, one can set

    Fig. 11.   Exporting the tunned set of routes for web application.

    Fig. 12.   Exported files for including these in the web application.

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    the number of single tourists, the number of couples, the number

    of families with babies, the number of families without babies

    and the number of groups of friends. Finally, one can also establish

    the number of iterations, which is referred as the  number of trips.The simulation applications starts with some default values in

    these parameters to facilitate beginners their first steps in the tool,

    but these can be altered by the user depending their goals. For

    instance, one can set the number of each tourist type expected to

    the next year, or who visited the city the last year, as reference val-

    ues. The simulation can also be designed for a specific month of the

    year (e.g. August or November). The number of trips is commonly

    used to obtain values from different iterations and achieve more

    reliable results mitigating the singular situations.

    After setting the parameters, one can run the simulation by

    pressing the  Run Simulation   button.   Fig. 10  presents an example

    of the results of the simulation for certain parameters. The bottom

    table displays the number of signed people to each route, indicat-

    ing its identifier and name. This table is scrollable so the user caninspect all the routes. This information can be used to tune a set of 

    routes and provide a more balanced set. Alongside these results,

    some additional information is presented in the   Results of 

    Simulation label and below it. This information is the time elapsed

    during the simulation, the number of agents used in the ABS, the

    number of routes, the number of iterations, the number of people

    represented by the agents in each iteration, and the number of peo-

    ple accumulated in the whole simulation taking into account the

    number of people per iteration and the number of iterations.

    After each simulation, the route designer can improve their set

    of routes with the specific recommendations for each tourist type.

    Once the route designer considers that they have an appropriate

    set of routes, they can export the routes to be uploaded in the

    web application. This exportation is performed by pressing button

    labeled as  Export Routes for Web Application, as one can observe in

    Fig. 11. After pressing the button, the user can select a directory of 

    their hard drive to store the routes in the format for the web

    application. When the exportation is complete, the label before

    the bottom table changes to   Exported Routes for Web Applicationindicating the number of exported routes, and displaying the

    routes in the table, as shown in this figure.

    In the directory selected for the exportation, five files are stored

    as one can observe in Fig. 12. All these files have all the routes, but

    each of these has the routes ordered decreasingly by the recom-

    mendations for a specific tourist type. Consequently, each file is

    named with the corresponding tourist type.

    Moreover, a web application is developed with the PHP

    programming language. The aforementioned generated files can

    be uploaded in a specific server directory location, and then the

    web application automatically considers the new uploaded data.

    An example of this web application is freely available from its

    website1, and is presented in Fig. 13.

    In this web application, the user can select the type of touristgroup they are planning to visit the corresponding city, and press

    the   Recommend Routes   button. Then, the web application recom-

    mends routes with ranking values from one (least recommended)

    to ten (most recommended) for the specific tourist type, decreas-

    ingly ordered according to these ranking values, as presented in

    Fig. 14.

    Finally, it is worth mentioning that sorting the routes for each

    tourist type is a task considered relatively time-consuming, i.e.

    with O(N log N) computational cost. The sort operation has been

    decided to be performed in the exportation process of the sim-

    ulation application instead of in the web application, because the

    exportation is considered to be less frequent than the repetitive

    queries of the corresponding tourists from the web application.

    Fig. 13.   Web application for recommending tourist Madrid routes.

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    4. Experimentation of ABSTUR with Madrid routes

    Several tourism experts have experienced ABSTUR for preparing

    appropriate sets of routes in the historic center of Madrid. In order

    to illustrate the current approach with ABSTUR, Section  4.1   pre-

    sents a specific simulation case in detail. In addition, Section  4.2

    compares the elapsed time in several simulations with ABSTUR 

    with another ABS that has been recently developed with the same

    specifications but without the presented adaptation framework.

    4.1. A simulation case

    In this simulation case, the tourism experts provided a set of 32

    routes in the historic center of Madrid. These routes were attachedto information such as detailed descriptions, the number of stages,

    their topics, their historic backgrounds, the related patrimonial ele-

    ments, the location of the stages, the beginning and ending places,

    the availability of cartography, the designer of each route, the

    owner and its grade of implication, the manager entity and its

    grade of implication, the main tourist locations, and whether they

    need to be integrated in specific schedules. Other information was

    also included like for instance whether a specialized guide is neces-

    sary, their economical cost, the availability of several languages,

    the accessibility, the duration, the length, the transport means,

    URLs to some webs that include photos among other things, and

    whether there is additional information in social networks. All this

    information about each route is omitted in this article for the sake

    of brevity. All the routes have identifiers, which allow experts andusers to easily associate the routes of the simulation with all the

    mentioned information. Bearing in mind all these data, some

    recommendation ranking values were assigned to each route for

    the different tourist types. The identifier of the route and its name

    were included in a file with all the recommendation values, follow-

    ing the format previously described in Section 3.3. The content of 

    this file is shown in the  Appendix A, and this file is used as the

    main input part of the simulation alongside the corresponding

    database with the data of routes.

    Besides the routes, the simulation receives input from other

    parameters such as the numbers of tourist types for each iteration,

    i.e. the number of singles, the number of couples, the number of 

    families with babies, the number of families without babies and

    the number of groups of friends. In addition, the simulation also

    receives input from the number of iterations (referred in the toolas the number of trips). The values of these input parameters are

    presented in Table 1 for this simulation case. The selection of these

    parameter values is based on the data provided by the Institute of 

    Tourism of Spain (Government of Spain, 2015).

    Fig. 14.   Example of recommendation for a given tourist type.

     Table 1

    Input parameters of the simulation.

    Input parameter Value

    Number of singles 300

    Number of couples 800

    Number of families with babies 250

    Number of families without babies 600

    Number of groups of friends 400

    Number of trips (iterations) 1200

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    In the simulation application, each family (with or without

    babies) has a random number of members from three to six, while

    each group of friends has a random number of members from two

    to ten.

    The tool running this simulation has already been presented in

    Fig. 10 of the current article. The number of the people signed up

    for each route is presented in  Table 2. As one can observe, there

    are several routes that are overcrowded with more than 349,000people signed up such as the routes named   Retiro and San

     Jeronimo,   Districts of Rastro and Lavapies: Genuine Madrid,   District 

    of Letters   and   Gran Via 100 years of History, while the   Historic 

    Madrid in Bicycle  route can be non-profitable with only 132,867

    people signed up. Some tourism exerts reflected on these results,

    in order to select another set of Madrid routes that produces a

    more balanced distribution of tourist people.

    The elapsed time of this simulation was 3203 ms. The sim-

    ulation was composed of 2350 agents. These agents represented

    7538 tourist people in each iteration. The tourist agents chose from

    32 routes. The simulation ran 1200 iterations. The accumulative

    number of all the iterations was 9,045,600 represented people.

    This number of people is similar to the number of people that actu-

    ally visited Madrid in 2012 (i.e. 9,056,504 people) according to the

    corresponding 2012 report provided by the Institute of Tourism of 

    Spain (Government of Spain, 2012).

    In fact, the execution of this simulation is considered to be quite

    efficient (more than nine million people in about 3.2 s). The main

    reasons are the omission of agent-specific communication plat-

    forms such as JADE, the use of only one agent for representing a

    group of several people, and the use of the same agent to represent

    similar groups of tourist people (e.g. families of four people

    without babies) through the different iterations. This simulation

    was run in a laptop with a processor Intel Core i7-3612QM

    2.1 GHz with Turbo Boost up to 3.1 GHz, 8 GB DDR3 RAM memory,

    and a graphics card NVIDIA GeForce 710 M with a 1 GB dedicated

    VRAM. This same hardware was also used in the other simulation

    experiments presented in the next subsection.

    4.2. Comparison of performance

    In order to assess the performance of ABSTUR, this has been

    compared with another later ABS that has been recently developed

    following the same specifications and using a blackboard architec-

    ture. In particular, this ABS was developed with the Erlang pro-

    gramming language, and used hash tables for representing the

    blackboard. This ABS received the same parameters as ABSTUR 

    such as the number of each type of tourist agents, the set of routes,

    and the number of iterations. The output was also the number of 

    people signed up for each route. This ABS runs when invoking

    the corresponding command from the Erlang environment with

    the appropriate parameters. Fig. 15 shows an example of execution

    of this ABS. This ABS also measures the time, in which the wall

    clock time represents the time that was actually consumed for per-forming the simulation.

    The performance of ABSTUR was compared with this other ABS

    with twelve different configurations. Both ABSTUR and the other

    ABS were run in the same hardware, which was detailed in the pre-

    vious section. The configurations were obtained departing from a

    default setting of 300 single tourists, 800 couples, 250 families

    with babies, 600 families, 400 groups of friends, a set of 32 routes,

    and 1200 iterations. The twelve configurations have been obtained

    maintaining these default values but changing respectively the fol-

    lowing parameters:

     The number of agents of each tourist type for all tourist types,

    with values 200, 400, 600 and 800.

     The sets of routes with respectively 10, 20, 30 and 40 routes.  The number of iterations, with values 500, 1000, 1500, 2000.

    Table 3 presents the results of this comparison of performance.

    The execution times are expressed with milliseconds (ms). For

    each simulation configuration, the ratio among execution times

    is calculated, and is denoted as the factor of improvement. This fac-

    tor is the division of the execution time of the other ABS between

    the execution time of ABSTUR. As one can observe, the average of 

    these improvement factors is 8.99 for the twelve pairs of tests.

    This suggests that ABSTUR is about nine times faster in average

    than the other ABS developed with the same specifications but

    without the presented adaptation framework.

    5. Conclusions and future work 

    In comparison to the existing expert and intelligent systems to

    the best author’s knowledge, ABSTUR is the first simulator that

    simulates how many people sign up for each tourist route from a

    given set of routes and tourists of certain types, considering both

    the characteristics of routes and the types of tourists with their

    preferences.

    This novel simulator has allowed tourism experts to simulate

    the implications of different sets of routes for certain numbers

    and types of tourists. In this way, ABSTUR has assisted tourism

    experts in designing an appropriate sets of routes for the historic

    center of Madrid, considering their implications about how many

    people will probably sign up for each route. In this manner, they

    were able to avoid both overcrowded tourist routes and non-profitable routes.

     Table 2

    Results of the simulation: the people signed up for each route.

    Id. of 

    route

    Id. of route People signed

    up

    CHG1 Barroco 275146

    CHG2 Palaces and Monasteries 323209

    CHG3 Restaurant and something more. All the tastes 252573

    CHG4 Historic Fonts 322179

    CHG5 Churches and Singulars 274044

    CGH6 Promenade of Madrid Art 330454

    CHG7 Goya in Madrid 1 332213

    CHG8 Goya in Madrid 4 285232

    CHG9 Ma riano Benlliure. M adrid itinerarie s 300519

    CHG10 Contemporary Art 291255

    LF1 Literary Madrid 288658

    LF2 Ancient Madrid 216586

    LF3 Madrid Villa and Corte 276934

    LF4 Elegant Madrid 331594

    LF5 Retiro and San Jeronimo 349478

    LF6 Panoramic visit 307230

    LF7 Panoramic visit and Royal Palace 237876

    LF8 Panoramic visit and Prado Museum 217696LF9 Panoramic visit and Thyssen-Bornemisza

    museum

    226381

    LF10 Panoramic visit and Reina Sofia museum 266597

    AGC1 The Madrid of Austrias 258716

    LF11 Night Panoramic 277103

    PDJ1 Historic Madrid in Bicycle 132867

    PDJ2 Districts of Rastro and Lavapies: Genuine

    Madrid

    349851

    PDJ3 Yesterday and today of Plaza Mayor 264879

    PDJ4 Distric t of M arav illa s a nd Conde D uque 301058

    PDJ5 Chueca : history , leisure a nd much more 276886

    PDJ6 District of Letters 349553

    PDJ7 Gran Via 100 years of History 349449

    PDJ8 Imagine Madrid(for families) 259356

    PDJ9 Madrid Treasures (for families) 261122

    PDJ10 Following the illustrious Artist Steps (for

    families)

    258906

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    distributions of tourist loads among different cities and towns of a

    given region. In this extension, the results will include a new

    column for indicating the city or town of each route, and the appli-

    cation will analyze and present the results gathering the tourist

    people signed up for the routes of each city and each town, as well

    as indicating the people signed for each route. Furthermore, the

    proposed adaptation framework for simulations is planned to be

    provided in a more automated way, maybe conforming a newplugin for IDK.

     Acknowledgments

    This work is supported by the project   Los Sistemas de

    Información Turística como herramientas tecnológicas para incremen-

    tar la operatividad tourística de los itinerarios culturales urbanos: El

    centro histórico de Madrid como proyecto piloto  (SIT-MAD) funded

    by the Hergar Foundation with Grant FH-2012-03. This work has

    also been done in the context of the project   Social Ambient 

     Assisting Living – Methods   (SociAAL), supported by the Spanish

    Ministry for Economy and Competitiveness, with Grant TIN2011-

    28335-C02-01. This work also acknowledges the   Fondo Social

    Europeo   and the   Departamento de Industria e Innovación del

    Gobierno de Aragón for their support.

     Appendix A. Content of the file with Madrid routes

    #Id.;Name;Single;Couple;Family;FamilyBabies;Friends

    CHG1;Barroco;10;8;7;2;6

    CHG2;Palaces and Monasteries;5;4;10;4;8

    CHG3;Restaurant and something more. All the

    tastes;8;10;6;1;5

    CHG4;Historic Fonts;5;10;6;7;7

    CHG5;Churches and Singulars;8;8;6;4;6

    CGH6;Promenade of Madrid Art;8;10;6;4;9

    CHG7;Goya in Madrid 1;8;10;6;4;9

    CHG8;Goya in Madrid 4;5;6;9;1;7

    CHG9;Mariano Benlliure. Madrid itineraries;8;6;6;4;9CHG10;Contemporary Art;8;10;6;4;6

    LF1;Literary Madrid;8;10;5;4;7

    LF2;Ancient Madrid;4;5;6;9;1

    LF3;Madrid Villa and Corte;8;7;4;4;9

    LF4;Elegant Madrid;8;10;6;4;9

    LF5;Retiro and San Jeronimo;5;10;6;7;9

    LF6;Panoramic visit;8;10;6;1;9

    LF7;Panoramic visit and Royal Palace;8;8;6;1;5

    LF8;Panoramic visit and Prado Museum;4;5;6;9;1

    LF9;Panoramic visit and Thyssen-Bornemisza

    museum;8;10;6;1;3

    LF10;Panoramic visit and Reina Sofia museum;8;5;6;1;9

    AGC1; The Madrid of Austrias;8;4;6;1;9

    LF11;Night Panoramic;10;8;7;2;6PDJ1;Historic Madrid in Bicycle;5;4;4;1;2

    PDJ2;Districts of Rastro and Lavapies: Genuine

    Madrid;5;10;6;7;9

    PDJ3;Yesterday and today of Plaza Mayor;5;3;4;7;9

    PDJ4;District of Maravillas and Conde Duque;5;9;6;7;6

    PDJ5;Chueca: history, leisure and much more;10;8;7;2;6

    PDJ6;District of Letters;5;10;6;7;9

    PDJ7;Gran Via 100 years of History;5;10;6;7;9

    PDJ8;Imagine Madrid(for families);1;3;10;10;1

    PDJ9;Madrid Treasures (for families);1;3;10;10;1

    PDJ10;Following the illustrious Artist Steps (for

    families);1;3;10;10;1

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