=Paper= {{Paper |id=Vol-1664/w10 |storemode=property |title=Supporting Learner-to-Learner Interactions Using Online Social Network Information |pdfUrl=https://ceur-ws.org/Vol-1664/w10.pdf |volume=Vol-1664 |authors=Pasquale De Meo,Fabrizio Messina,Domenico Rosaci,Giuseppe M. L. Sarné |dblpUrl=https://dblp.org/rec/conf/woa/MeoMRS16 }} ==Supporting Learner-to-Learner Interactions Using Online Social Network Information== https://ceur-ws.org/Vol-1664/w10.pdf
                                                                                                                                                  1




 Supporting Learners-to-Lerners Interactions Basing
      on Online Social Networks Information
                Pasquale De Meo and Fabrizio Messina and Domenico Rosaci and Giuseppe M. L. Sarné




   Abstract—E-Learning students can benefit from proper class                  experiences [15], [21]–[26] we designed a model to manage
formation process based on the student needs. In particular,                   formation and evolution of e-Learning classes by using user
Online Social Networks make available data concerning users’                   information available on OSNs. These information are linearly
interactions, as skills and trust relationships, that are behind
the dynamics of thematic social network groups, and can be                     combined in a measure, named convenience, used to suggest
explouted to form e-Learning classes. To this aim, we propose a                the best class (student) to join with or leave (to accept or
model based on such information, which are properly combined                   remove) to a user (to the class itself). First of all, the skills of
to support the dynamics of e-Learning classes on Online Social                 a student with respect to a set of topics of interest represent
Networks. The approach provide a way to give suggestions to                    the basic aspect we considered to give teaching-homogeneity
users about the best classes to join with and to class adminastrors
the best students to accept. The proposed approach has been                    to the class [27], in order to balance “supply” and “offer” of
tested by simulating an e-Learning scenario within a large social              support requests (i.e. interactions). Trust represents the second
network by showing its capability to satisfy all the actors.                   component, which is computed by combining several specific
  Index Terms—Social Networks; Software Agents; Thematic                       factors – which are related to specific e-Learning concerns –
Groups                                                                         giving a complete trust model based on reliability and repu-
                                                                               tation criteria and on some countermeasures for erroneous or
                          I. I NTRODUCTION                                     malicious opinions. The model is designed to assists students
                                                                               and classes by means of personal software agents delegated
   E-Learning (EL) represents a good solution for courses, as                  to create, manage and update the profiles of their owners on
it provides time and location flexibility, low costs and informa-              the basis of information found on the OSNs. The convenience
tion sharing [1]. In this context, among the factors affecting                 measure is exploited by a distributed procedure, named Class
learners progresses there are personal attitudes, initial skills               Formation (CF), that allows learner/class software agents to
and the level of mutual trust, which influences the attitudes                  appropriately cooperate to form classes.
of peers to start interactions [2] and minimizes the cold start
                                                                                  The experimental trials have shown that running the CF
effect. Given that those information are widely available in
                                                                               algorithm allows students and class administrators to improve
Online Social Networks (OSNs), EL activities can benefit from
                                                                               the average value of the convenience within classes.
synergies with OSNs. Besides, many OSN platforms [3], [4]
                                                                                  The rest of the paper is organized as follows: Section II
support thematic groups that, for their relevance, have been
                                                                               introduces the context and the Expertize, Trust and Advan-
largely investigated [5]–[9].
                                                                               tage measures. The proposed architecture is described in
   In addition, software agents can support EL class formation
                                                                               Section III, while Section IV discusses the GF algorithm.
processes by suggesting to students (classes) about the best
                                                                               Section V presents the experiments we carried out, Section VI
classes (students) to join with (to accept) [10]–[12]. Studies
                                                                               examines related literature and, finally, in Section VII we draw
confirmed that, within social communities, users start to inter-
                                                                               our conclusions.
act and share information with other peers also based on the
level of mutual trust existing among users [13]–[18]. Besides,
also in forming OSN groups existing trust relationships can
                                                                                     II. E -L EARNING INTERACTIONS AND MEASURES
give a significant contribution, in addition to a similarity
criterion [13], [19], [20].                                                       Let be N the set of OSN members, (||N || = N ), C the set
   It is obvious that, due to the huge amount of data of OSNs                  of classes (||C|| = C), with each class c ∈ C consisting of a
and the huge number of thematics groups, examining the                         number of learners and at least a teacher. We also suppose that
entire space of data to suggest suitable solutions for learners’               each user ui ∈ N is associated with a software agent [28] ai
needs is impracticable. Therefore, based on previous research                  able to obtain a view on the ui background and attitudes and
   Pasquale De Meo is with the Dept. DICAM, University of Messina, Viale
                                                                               to assist him/her in joining with or leaving classes. Similarly,
Andrea Doria, 6 - 01010 Messina, Italy, e-mail: p.demeo@dmi.unime.it           each manager is assisted by a software agent, denoted as Ai ,
   Fabrizio Messina is with the Dept. DMI, University of Catania, Viale        in deciding whether a new member can be accepted in the
Andrea Doria, 6 - 01010 Catania, Italy, e-mail: messina@dmi.unict.it
   Domenico Rosaci is with the Dept. DIIES, Unversity Mediterranea of
                                                                               class.
Reggio Calabria, Loc. Feo di Vito - 89123 Reggio Calabria, Italy, e-mail:         We also define a behavioral measure, which is related to the
domenico.rosaci@unirc.it                                                       interactions carried out by a learner (see Section II-A) and a
   Giuseppe M. L. Sarné is with the Dept. DICEAM, Unversity Mediterranea
of Reggio Calabria, Loc. Feo di Vito - 89123 Reggio Calabria, Italy, e-mail:   trust measure, which considers the level of mutual trust among
sarne@unirc.it                                                                 OSN members (see Section II-B).


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A. Behavioral Measures                                                   other OSN users to compute their respective reputations. Such
   The principle behind the definition of the behavioral mea-            feedbacks refer to the quality of these interactions (remember
sures is that, in order to form classes, a balance between re-           that users’ skills are evaluated by the Behavioral measures).
quired and/or offered skills should be desirable, as each learner           Let ηp,r and ρp,r be respectively the measures of reliability
is interested to improve his/her knowledge by joining with               and reputation that the OSN user up (i.e. agent ap ) computes
classes where the other members have suitable capabilities               for the OSN user ur (i.e. agent ar ). The trust measure τp,r is
and managers of classes are interested to include users holding          obtained by combining the reliability (ηp,r ) and the reputation
skills and attitude to interact.                                         (ρp,r ) weighted by means a coefficient βp,r ∈ [0, 1] ∈ R:
   Classes. Let’s define a class c as a tuple hS, W, Vc , oi where:                  
(i) S = {s1 , s2 , . . . , sm } is the skill set required by the class                  0.5                              if Ip,r = 0
                                                                              τp,r =
manager of c; (ii) W = {w1 , w2 , . . . , wm } is the weight set                        βp,r · ηp,r + (1 − βp,r ) · ρp,r if Ip,r > 0
used to evaluate the students’ skills; (iii) Vc is the minimum           where Ip,r is the number of interactions occurred be-
overall skill grade, computed over the specific skill set S,             tween the two actors. Note that for new learners the initial
required to join with c; (iv) o is the reference topic or subject or     trust/reputation is set to 0.5 to contrast whitewashing strate-
goal of c. More formally, for an OSN user uk and a skill set S,          gies [31]. For computing βp,r , we consider that its value
            Pm
V (k, S) =      wi · g(k, si ), where g(k, si ) ∈ [0, 1] ∈ R is the      increases with the number of interactions occurred between
            i=1                                                          the two learners because their direct knowledge improves
knowledge grade of uk for the skill si , while wi ∈ [0, 1] ∈ R
                                               P
                                               m                         over time and decreases when the reliability in providing
is set by the class manager to weight gi with     wi = 1.                recommendations decreases (the reputation or some peers may
                                                    i=1
  The User attitude H. The attitude of the user uk to require            be affected by malicious behaviors); Therefore, the coefficient
and/or offer interactions for his/her skills is computed as:             βp,r is computed as:

              H(k) = α · H(k) + (1 − α) · H(k)                                            βp,r = M ax(β1 , β2 )
                                                                                                
where the new value of H ∈ [0, 1] ∈ R combines, weighted                                 Ip,r
                                                                         where β1 = min Imax
                                                                                                                (t)
                                                                                              , 1 and β2 = 1−Ωp,r . The parameter
by a system parameter α ∈ [0, 1] ∈ R, the previous value and              (t)
a contribution H for the new interactions computed as:                   Ωp,r is the average confidence at time t for the current set of
                                                                         recommenders that provided at least a recommendation to ap
               |h(k)
H(k) = 1 − h(k)req
                       −h(k)
                        of f    |
                                     if    h(k)req + h(k)of f 6= 0                                (t)            PRp,r (t−1)
               rec +h(k)of f                                             about ar computed as Ωp,r = ||Rp,r 1
                                                                                                              ||   i=1 |σp,r     −τq,r | and
or H(k) = 0.5 otherwise, and where h(k)req and h(k)of f ,                where Rp,r is the set of agents provided an opinion about ar . It
with respect to uk , respectively are the evaluation of the              minimizes the effect of untrustworthy opinions by giving more
interactions for a number Nreq and Nof f of skills subset                relevance to those mentors evaluated by ap as the most similar
Si ⊂ S requested and offered at the new step obtained by:                to it. Ip,r is the number of interaction that is incremented at
                             PNreq                                       each step and when it is greater than the threshold Imax then
                         1
              h(k)req = Nreq    i=1 g(k, Sreq,i )                        the “knowledge” between two users is considered maximum.
                             PNof f
                         1
             h(k)of f = Nof f i=1 g(k, Sof f,i )                         As a result, the contribute of the reputation in computing trust
                                                                         decreases as much as the number of the interactions occurred
Therefore, when h(k)req ≈ h(k)of f , then H ≈ 1, i.e. the                between the two involved learners constantly increases.
user uk asks and provides interactions to the same extent.                  1) Computation of Reliability: The reliability measure,
Vice versa, his/her attitude is mainly to offer (or require)             ηp,r ∈ [0, 1] ∈ R, is computed by up (i.e. ap ) about ur
interactions, i.e. H ≈ 0.                                                (i.e. ar ) as ηp,r = ϑp,r · σp,r + (1 − ϑp,r ) · ηp,r , where the
   Class Behavior. The class behavior for the class cj , denoted         parameter ϑp,r weights in a complementary way the feedback
as B(j) ∈ [0, 1] characterizes its tendency to offer or require          parameter σp,r ∈ [0, 1] ∈ R computed on the last interaction
                                                 P||cj ||
interactions and it is defined as B(j) = ||c1j || k=1     H(k).          occurred between up and ur at time-step t and the value of
                                                                         ηp,r computed at time-step (t − 1).
B. Trust Measure                                                            The parameter ϑp,r considers the relevance assigned to the
   The second measure is based on the concept of trust [29]              interaction between up and ur , let it be Ψp,r . In principle,
and it is computed by combining two factors, namely reliabil-            malicious behaviors aimed to gain good reputation with low
ity and reputation. The former measure derives by the direct             value interactions (Ψ ≪ 0.5) but high reliability (σ ≫ 0.5)
knowledge between truster and trustee due to their interactions          can start on interactions of high relevance (Ψ ∼ 1) (due to
occurred in the past, while reputation is an indirect knowledge          a good reputation) but providing poor performance (σ ∼ 0).
derived by the past interactions occurred among the trustee              Therefore, the closer the ratio Ψ/σ to 1, the higher the value
with other counterparts different from the current truster [30].         of ϑ; the farther the value Ψ/σ from 1, the lower the value of
   An interaction between two generic OSN learners up and ur             ϑ. A possible choice for ϑ is represented by the adoption of
                                                                                                                           2   2
consists of a process where up starts with one or more learning          the Gaussian centered in 1, as ϑ = e−(Ψ/σ−1) /v . ϑ acts as
tasks with ur . Consequently, their software agents ap and ar            a “filter” for those values of σ which, for the correspondent
observe the interactions of their owners to register the interac-        values of Ψ, may reflect a malicious behavior, while large
tion features (type, topic, duration) and collect feedbacks about        values of v will select only those values of σ for which σ/ϑ


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is close to 0 by ensuring that almost the whole history of           class and Aj the associated software agent, the following tasks
feedbacks σ is considered in computing η.                            are triggered by the interactions among software learner agents
   2) Computation of Reputation: The reputation measure              ak and the class agent Aj as: (i) Any message of ak containing
ρp,r ∈ [0, 1] ∈ R is computed by up (i.e., ap ) with respect         updated Behavioral and/or Convenience measure will trigger
to ur (i.e. ar ) as a value ranging in [0, 1] ∈ R:                   agent Ak to update Behavioral and/or Convenience measures
                                      ||Rp,r ||                      for the whole class; (ii) Whenever the Behavioral measure of
                                       X                             the class cj has changed, Aj will send the updated measure
                              1
                   ρp,r = ||Rp,r ||               τq,r
                                        q=1
                                                                     to all the learner agents of the class cj ; (iii) Ak will assist
                                                                     the class manager of cj to take decision about the requests
Through the usual meaning of these indexes, 0/1 means that           coming from agents ak to join with or leave classes.
ur is totally unreliable/reliable.
                                                                            IV. T HE DISTRIBUTED PROCEDURE FOR C LASS
C. Convenience Measure                                                                    F ORMATION (CF)
   Behavioral and trust measures are combined to measure the            In our approach, each Learner Agent has: (i) to update
convenience, for a user, to join with the class cj . The asymmet-    all the proposed measures whenever one or more interaction
ric nature of the trust measure implies also the asymmetry of        occurred, (ii) to send the new values to its class agents and (iii)
the convenience. In particular, let φ be a parameter computed        to assist its own user to take decision about joining with or
as φ = (1−|H(k)−B(j)|)
                ||cj ||     , where ||c|| is the number of users     leaving classes by executing the CF algorithm (For this aim, it
(i.e. agents) affiliated with c. Then the convenience (γu,c ) for    will receive behavioral and trust measures from its own class
the user u to join with the class c, and that (ηc,u ) of the class   agents).
c to accept the affiliation request of a user u are computed as:        Each class agent has (i) to wait for learner agents messages
                    X                             X                  in order to update the proposed measures of the entire class,
        γk,j = φ         τk,i           ηj,k = φ       τi,k
                                                                     (ii) to send updated behavioral measure for allowing learner
                 ai ∈cj                                  ai ∈cj
                                                                     agents to update their own convenience measures and (iii) to
   Both measures increase with the difference between the            assist its own class manager to take decision about the requests
behaviors of ak and cj . As a consequence of the asymmetric          coming from learner agents to join with or leave classes.
nature of trust, the procedure described in Section IV is dis-
tributed among the agents assisting learners and those assisting
                                                                     A. The distributed CF procedure.
class managers. As it will be discussed in the experimental
Section, the aim of the distributed procedure is to let the             Let T be the time between two consecutive steps of the CF
system to reach a balance in terms of convenience among all          procedure executed by the generic learner agent, in order to
the considered actors of the proposed OSN EL scenario. [32]          join with a set of classes of the same topic. We also suppose
                                                                     that agents can query a distributed database named CR (Class
   III. T HE MULTI - AGENT E -L EARNING ARCHITECTURE                 Repository) on which the list of the classes is stored.
                                                                        The CF procedure performed by the learner agents (See
   In the proposed approach, OSN users (i.e. learners) are sup-      Fig. 1(a)). Let Xn be the set of the classes the agent an is
ported by intelligent software agents [33] capable to perform        affiliated to, and NM AX the maximum number of classes an
all the activities aimed at organizing classes basing on the         agent can analyze at time t, with NM AX ≥ |Xn |. Besides,
measures presented in Section II. All the agents execute a set       suppose that an stores into a cache the class profile of each
of tasks which are briefly summarized below, and categorized         class contacted in the past and the timestamp d of the last
as Learner Agent Behavior and Class Agent Behavior.                  run of the CF procedure for that class. Let the timestamp
   The Learner Agent Behavior. The behavior of a learner             ξn and χn ∈ [0, 1] be two thresholds fixed by the agent an .
agent consists of several tasks periodically executed to main-       The ratio of the procedure for the learner agent is to improve
tain data useful to run the CF algorithm (see Section IV). Let       the convenience in joining with a class. Therefore, firstly the
uk be the generic learner and ak his/her agent, the following        values of convenience are recalculated if older than ξn (lines
tasks are triggered by the learner and executed by the agent         1-4). Then, candidate classes are sorted in a decreasing order
as: (i) Any interaction of learner uk with one or more peers         based on their Convenience value (line 5). In the loop in lines
will trigger agent ak to update Behavioral measures; (ii) Any        7-16 the NM ax classes are selected. If the classes in the set
reliability change of a user uj that interacted with a peer,         Lgood are not in the set Xn , then agent an could improve the
will trigger ak to update the Reliability measure; (iii) The         convenience of the owner if the classes accept the user for
Convenience measure will be updated for any change in the            joining with.
Reliability measure; (iv) Behavioral and Trust measures are             The CF procedure performed by the class agent - Fig. 1(b).
periodically sent to the class agent once and if they have been      Let Kc be the set of the agents affiliated to the class c, and
recalculated; (v) The generic software agent ak will assist user     KM AX the maximum number of learners allowed to be within
uk to take decision about joining with or leaving classes.           the class c 1 with ||Kc || ≤ KM AX . Suppose that the class
   The Class Agent Behavior. The behavior of a Class Agent           agent Ac stores into a cache the profile P of each user u
consists of several tasks executed periodically to maintain data
useful to run the CF algorithm (see Section IV). Let cj be a           1 For convenience it is assumed the same for all the classes and topics




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Input:                                                                   by cj ∈ C for all its students ui ∈ cj . To measure the
  Xn , NM AX , ξn , χn ;                                   T             global convenience
                                                                                         P of all the classes of N , we computed the
  Y = {c ∈ S C} a random class set : |Y | ≤ NM AX , Xn Y = {0},
                                                                         mean M AC = cj ∈C ACj /||C|| and the standard deviation
  Z = (Xn Y )                                                                     qP
  1: for c ∈ Z : dc > ξn do
                                                                                      cj ∈C (ACj − M AC) /||C|| .
                                                                         DAC =                             2
  2:     Send a message to Ac to retrieve the profile Pc .
  3:     Compute γun ,c                                                     A first test involved three scenarios consisting of 50, 100,
  4: end for                                                             and 200 e-Learning classes, as summarized in Table I. To
  5: Let be Lgood = {ci ∈ Z : i ≤ j → γun ,ci ≥ χn }, with
     |Lgood | = NM AX                                                    compute the convenience, we assumed that 20% of OSN
  6: j → 0                                                               members is unreliable. Behavioral coefficients hreq and hof f
  7: for c ∈ Lgood ∧ c 6∈ Xn do                                          and the values of trust (τ ), have been sampled from a normal
  8:     send a join request to Ac
  9:     if Ac accepts the request then                                  distribution [34] around specific mean and standard deviation
 10:         j → j+1                                                     (stdev), see Table I. In particular, τr is the mean of generated
 11:     end if                                                          trust values for reliable users, while τu is the mean for unre-
 12: end for
 13: for c ∈ {Xn − Lgood } ∧ j > 0 do                                    liable users. Moreover, for this set of experiments, the ratio
                                                                                max ·|C|
 14:     Sends a leave message to c                                      r= K  Nmax ·|U | was set to 1. Besides, the starting composition of
 15:     j → j−1                                                         classes is random. Table II shows the results of the execution
 16: end for
                                                                         of the CF algorithm for the three scenarios reported in Table I,
                                                                         that shows the initial value of MAC/DAC (epoch T0 = 0) and
Input:                              S
  Kc , KM AX , ωc , πn , ar , Z = Kc {ar };                              the final one (epoch Te = 20). Indeed, we have verified that
                                                                         after 20 epochs of executions, the M AC has reached a very
 1: if (V (r, Sc ) < Vc ∨ |Kc | ≥ KM AX ) then                           stable value. It can be observed that, the improvement, in terms
 2:     Send a reject message to ar                                      of MAC, at the end of the experiments, is about the 8% for all
 3: else                                                                                                             max ·|C|
 4:     for a ∈ Kc do                                                    the configurations and, since the ratio K Nmax ·|U | is the same for
 5:          if du ≥ ωc then                                             the three scenarios without relevant variations, the subsequent
 6:              ask to a its updated profile                            were driven by r.
 7:          end if
 8:     end for                                                             For the second set of experiments we assumed a variable
                                                                                           max ·|C|
 9:     for a ∈ Z do                                                     value of r = K   Nmax ·|U | , as shown in Table III, ranging from
10:          compute ηc,a
11:      end for
                                                                         0.1 to 0.9. A value r < 1 say us that users, in overall, can join
12:      Let be Kgood = {a ∈ Z : γc,a ≥ πc }                             more places (Nmax · |U |), than the total allowed (Kmax · |C|).
13:      for a ∈ Kc − Kgood do                                           In particular, the best improvement, in terms of M AC, is for
14:          send a leave message to a.
15:      end for
                                                                         r = 0.4 (+20%), r = 0.5 (+16%) and r = 0.6 (+20%).
16:      if ar ∈ Kgood then                                              It means that, from one hand, finding a class to improve the
17:          the request of ar is accepted                               personal convenience γ is a bit more difficult for the user
18:      end if
19: end if
                                                                         when r < 1, therefore the CF algorithm helps to improve
                                                                         the MAC with respect to the random composition of classes.
Fig. 1. CF algorithm. Top (a): Learner Agent. Bottom (b): Class Agent    Nevertheless, the algorithm clearly needs a certain degree of
                                                                         freedom to give some benefits. Therefore, when r is very
                                                                         small, the improvements, in terms of M AC are comparable to
managed by his/her learner agent a ∈ Kc and the timestamp
                                                                         those given for values of r close to 1. In overall, these results
du of its acquisition. The procedure run by Ac is triggered
                                                                         point out that the CF algorithm gives, on average, a relevant
whenever a join request by a learner agent ar (in the interest of
ur ) is received by Ac (with the profile Pr ). Let the timestamp
ωc and πn ∈ [0, 1] be two thresholds fixed by the agent Ac .
                                                                                                      TABLE I
If the class has reached this maximum, no more students will                           CF ALGORITHM . S IMULATION PARAMETERS
be accepted. By lines 4-8 the class agent asks the updated
profile of its students to update their convenienceS γc,a (lines
                                                                                         Sc.      |C|     |U |    KM ax     NM ax
9-11) so that a new sorted set Kgood ⊂ {Kc ar } is built                                 1        50      200
                                                                                         2        100     400      20         5
(line 12). Then, the class agent (i) will send a leave message                           3        200     800
to all the learner agents a having a convenience γc,a or (ii) if
                                                                                                     τr      τu    {hReq , hof f }
ar ∈ Kgood (line 16), the agent request is accepted.                                      mean      0.8     0.3    0.5, 0.5
                                                                                          stdev     0.2     0.2    0.2, 0.2

                         V. E XPERIMENTS
   In order to evaluate the described approach, we performed                                            TABLE II
                                                                                                  R ESULTS WITH r = 1.0
some experiments to investigate on the convergence of the
CF algorithm described in Section IV. As a measure of                                       Sc 1                Sc 2             Sc 3
the internal convenience for a class cj , we introduced the                             MAC DAC             MAC     DAC      MAC DAC
concept of Average Convenience (AC), computed as the                              T0     0.63    0.12        0.62    0.12     0.62    0.12
                                                                                  Te     0.67    0.10        0.66    0.10     0.67    0.12
average of all the measures of convenience ηj,i computed


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                                                TABLE III                                                                  By means of these data, suitable metrics can be created to
                                               MAC AND DAC                                                                 weight the “edges” between users. The proposed algorithm to
               r=0.1                  r=0.2                  r=0.3                  r=0.4                  r=0.5
                                                                                                                           form groups simply explores the whole OSN to find a minimal
 T0
       MAC
        0.61
                       DAC
                       0.07
                              MAC
                               0.59
                                              DAC
                                              0.02
                                                     MAC
                                                      0.60
                                                                     DAC
                                                                     0.03
                                                                            MAC
                                                                             0.60
                                                                                            DAC
                                                                                            0.04
                                                                                                   MAC
                                                                                                    0.60
                                                                                                                   DAC
                                                                                                                   0.08
                                                                                                                           number of proper candidates to form a group able to optimize
 Te     0.61
               r=0.6
                       0.08    0.63
                                      r=0.7
                                              0.08    0.69
                                                             r=0.8
                                                                     0.04    0.70
                                                                                    r=0.9
                                                                                            0.10    0.73           0.06
                                                                                                                           a group EL experience. Differently, we exploit the concept of
 T0
       MAC
        0.60
                       DAC
                       0.07
                              MAC
                               0.63
                                              DAC
                                              0.09
                                                     MAC
                                                      0.63
                                                                     DAC
                                                                     0.09
                                                                            MAC
                                                                             0.62
                                                                                            DAC
                                                                                            0.11
                                                                                                                           trust by combining reliability and reputation. Finally, in [43]
 Te     0.70           0.09    0.69           0.08    0.68           0.08    0.67           0.10                           the student use of Facebook at the University of Cape Town
                                                                                                                           is analyzed by showing positive benefits to build EL micro-
                                                                                                                           communities on Facebook but certain existing challenges, as
improvement of the convenience for the classes. [35]
                                                                                                                           including ICT literacy and uneven access, remain opened.
   In order to test the effectiveness of the trust model we have
verified, by simulations, that the class formation algorithm
will lead to high and stable values of average convenience.                                                                              VII. C ONCLUSIONS AND FUTURE WORK
Simulations have shown that the CF algorithm will lead                                                                        Class formation in e-Learning is a critical task for the
significant benefits in terms of average quality of interactions.                                                          quality of such activities. In this work we focused on a
                                                                                                                           distributed algorithm supported by a trust model and some
                                 VI. R ELATED W ORK                                                                        behavioral measures based on information coming from the
                                                                                                                           OSN (i.e. users trust relationships, interaction quality, histor-
    Group/class formation is an important task to promote EL                                                               ical attitude to interact with peers) to improve the metrics
activities and obtain effective results [36]. In particular, form-                                                         for dynamic class composition in OSNs. This flexibility is
ing random groups/classes may cause absence of participation                                                               aimed at improving the quality of learning experiences and it
and motivation [37]. A recent survey on group/class forma-                                                                 is obtained by combining information about trust and previous
tion [38] analyzes about 250 works. The authors discovered                                                                 interactions in a unique measure named “convenience”. In this
that the 20% of studies on group formation in collaborative                                                                work we have shown a first set of experimental results obtained
EL and a 20% of them adopt probabilistic models, while                                                                     by simulating an artificial scenario with a variable number
the remaining studies rely on various AI techniques. Among                                                                 of users and groups. The results have shown that the class
them, an interesting work deals with strategies for group                                                                  formation algorithm will lead to high and stable values of
formation based on individual behaviors [39] obtained by                                                                   average convenience.
monitoring communication data. The results show that the                                                                      As future work, we will perform a further experimental
students participation in small groups is correlated with their                                                            campaign in order to verify that the convergence to high values
behavior in the class. Therefore, authors suggest to use these                                                             of convenience leads to significant benefits in terms of average
information to allocate heterogeneously initial classes into                                                               quality of interactions. Moreover, a further set of experiments
small groups. It partially differ from our approach that is                                                                is needed to verify the effectiveness of the trust model to
aimed at grouping individuals with similar behaviors, in terms                                                             limit malicious behaviors, in order to give trust values which
of “positive” and “negative” interactions. Besides, a relevant                                                             reflect the actual behavior, in terms of overall reliability, of
component in our proposal are the trust relationships from                                                                 the students.
OSN data that in [39] is neglected.
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