=Paper= {{Paper |id=Vol-3180/paper-207 |storemode=property |title=Graph-Based Profile Condensation for Users Profiling |pdfUrl=https://ceur-ws.org/Vol-3180/paper-207.pdf |volume=Vol-3180 |authors=Roberto Labadie-Tamayo,Daniel Castro-Castro |dblpUrl=https://dblp.org/rec/conf/clef/TamayoC22 }} ==Graph-Based Profile Condensation for Users Profiling== https://ceur-ws.org/Vol-3180/paper-207.pdf
Graph-Based Profile Condensation for Users Profiling
Notebook for PAN at CLEF 2022

Roberto Labadie-Tamayo1 , Daniel Castro-Castro2
1
    Computer Science Department, University of Oriente, Santiago de Cuba, Cuba
2
    Information Retrieval Lab, Computer Science Department, University of A Coruña, Spain


                                         Abstract
                                         For social media profiling tasks, it is crucial the way information regarding user accounts is modeled
                                         and aggregated, especially when exploring micro-blogging platforms such as Twitter. In this paper, we
                                         describe our system for participating in the “Profiling Irony and Stereotype Spreaders on Twitter” task
                                         shared on PAN 2022, which analyses the user account with a graph-based modelation. The approach
                                         relies on a 𝛽-similar graph construction, whose nodes represent tweets within the account, encoded as a
                                         combination of irony and stereotyping-related features. The graph’s information is propagated through
                                         a Spacial Attention-based Graph Neural Network and prototype nodes are selected and aggregated to
                                         classify the profile with a Feed-forward Neural Net.
                                         We also describe a second model supported by a profile reduction whose ideas would be introduced to the
                                         graph construction under the assumption that given an ironic profile, non-ironic tweets may introduce
                                         some noise at the classification stage and vice versa.
                                         Experimental results show this graph modelation solves issues detected in previous related proposals,
                                         also the profile reduction yields a profile kernel containing valuable and non-noisy information for
                                         classifying the user accounts.

                                         Keywords
                                         Spacial Graph Neural Network, Attention Mechanisms, Semantic Similarity, Profile Kernels, Prototypes




1. Introduction
Social media has provided users with an unprecedented and multi-modal means to interact with
each other and express themselves. The language employed in these platforms typically exhibits
a natural flow of speech and grammatical structure involving creative and figurative devices
such as irony and sarcasm, which add complexity to the automatic analysis of the information
posted by users.
Specifically, when using irony, people utter something different from what is wanted to express
(i.e., typically the opposite of the true appraisal of circumstances), but it is expected the lis-
tener/reader to recognize the overt dissimulation by seeing through the counterfactual nature
of the utterance and eventually detect the intended meaning of what is said [1].
It is very common to find out on social media a bunch of content employing this device to
spread hateful and toxic expressions into a particular process, entity, or even groups of persons
with some demographic or psychological characteristics by stereotyping them. The latter shows
CLEF 2022 – Conference and Labs of the Evaluation Forum, September 5–8, 2022, Bologna, Italy
$ rlabadiet@gmail.com (R. Labadie-Tamayo); daniel.castro3@udc.es (D. Castro-Castro)
 0000-0001-9102-7601 (D. Castro-Castro)
                                       © 2022 Copyright for this paper by its authors. Use permitted under Creative Commons License Attribution 4.0 International (CC BY 4.0).
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                  ISSN 1613-0073       CEUR Workshop Proceedings (CEUR-WS.org)
why it’s imperative to discriminate whether some content is ironic in order to filter what is
delivered to a user or censure the one harmful and socially inappropriate. Nevertheless, if we
take into account that in this kind of media the receptors of written messages are deprived of
additional knowledge from gestures, prosody features, visual content, and sometimes situational
environment, which are crucial for understanding such a figurative form of communication
as irony is, we can certainly assume that complexity increases for automatic methods. These
methods need to consider at least socio-cultural rules to properly understand the real meaning
behind funny but hateful material.
Twitter as one of the most popular microblogging platforms on the internet, has not escaped
from the raising of misinformation and hate speech spreading phenomena, constituting an
important source of toxicity. Following this line Author Profiling (AP) tasks have been proposed
to identify psychosocial characteristics of Twitter users [2, 3, 4] that could help to detoxify this
scenario.
Last year at PAN 2021, was proposed the task: “Profiling Hate Speech Spreaders on Twitter” [4]
where systems were developed to determine whether a Twitter account tends to spread hateful
speech. A diversity of models reasonably able to profile authors were proposed by participants,
employing techniques ranging from traditional Machine Learning approaches to more novel
methods involving Convolutional, Recurrent, and Graph-based Neural Networks [5, 6, 7].
This year a more complex task in terms of understanding and associativity with contextual
knowledge has been proposed at PAN 2022 [8]: “Profiling Irony and Stereotype Spreaders
on Twitter” (IROSTEREO) [9], aiming at profiling ironic authors on Twitter, paying special
attention to those which mask stereotyping content by employing irony.
Many works have been proposed for predicting automatically whether a textual message is
ironic. These methods rely mainly in the use of Recurrent Neural Networks [10] or more recently,
fine-tuned Transformer Models [11] and conventional Machine Learning models like Logistic
Regression [12] or Support Vector Machines (SVM) [13]. Stereotypical language detection has
also been well-studied [14, 15, 16] yielding proposals aligned with the use of architectures
employed for irony detection, such as [17] with Transformer models.
Regarding the Author Profiling field, the way of aggregating the information of isolated
tweets/texts from the author account has also been studied, especially in the last edition of PAN
were employed successfully different methods such as sequential representations, single-dense
vectors, and graph-based representations.
In this work, we describe our system for participating in the “Profiling Irony and Stereotype
Spreaders on Twitter” task at PAN 2022 and explore with an incremental modeling complex-
ity how to structure the information obtained from a Twitter user account for classifying it
regarding the proposed task. Our general architecture combines Deep Learning techniques
with traditional ones from Machine Learning, particularly, it consists of a Sentence Encoder
Module, based on a transformer architecture for obtaining abstract tweet representations. These
encodings are employed for modeling and classifying the user’s profile. The source code of our
approach is available on GitHub1 .
The paper is organized as follows: In Section 2 we briefly describe the task proposed and datasets
employed. Section 3 presents the system’s architecture and provides details about its modules.

    1
        https://github.com/labadier/IROSTEREO
Section 4 describes the experiments and the achieved results. Finally, we present our conclusions
and provide some directions that we plan to explore in future works.


2. Task and Datasets
This year the Profiling Task at PAN, in contrast with its last editions, is deployed in a monolingual
perspective, analyzing just the English language. It aims at classifying a Twitter user account
as an Irony and Stereotypes Spreader or not, given 200 posts from its feed. Also, as a subtask,
participants are asked to determine whether the use of stereotypical language was intended
to hurt or support the targeted social group. The dataset provided by the organizers [18], as
usual, only contains annotations at the profile level and is balanced concerning the positive and
negative classes distribution for the first subtask. For the second subtask, the hurting class is
underrepresented.
We introduce additional data from the training set proposed in Task 3A at SemEval-2018: “Irony
Detection in English Tweets” [19], annotated regarding the presence of irony and also uniformly
distributed for positive and negative classes. This training set is composed of 3817 data points,
with 1901 examples of ironic messages.
The training set from SemEval-2019 Task 5: Detection of Hate Speech Against Immigrants
and Women in Twitter (HateEval)[20] was also taken into account. This dataset is annotated
regarding the hateful speech towards specific social groups, the presence of an aggressive
language, and its range, indicating whether the hate targets a person or a group. It contains
9000 tweets for the English language, with 3783 annotated as hateful. In this work, it is of our
interest just the latter information from the dataset.


3. System Description
As in previous works [6, 7] our system relies on a modular architecture, conditioned by the use
of data representations learned through fine-tuned state-of-the-art neural language models;
while introducing a more sophisticated modelation and aggregation for the Twitter feed and
whose improvement target is to bypass as much as we can the hyperparameters from Deep
Impostor Method in [7]. We also propose a non-graph-based system to compare with this
modelation.
From a general standpoint, given a user account, our system at first approach the tweet encoding
to afterward aggregate them and classify the profile in IROSTEREO spreader or not. This
procedure also applies to the stance detection subtask.

3.1. Data Representation
Three pre-trained Transformers Language Models (LMs) [21] were employed to encode in a
dense way the semantic information contained in a tweet. All three employ the BERT-base [22]
configuration but are pre-trained or fine-tuned into a different data domain.
The first model, a simple BERT-base, pre-trained on a dataset consisting of 11,038 unpublished
books from BookCorpus2 and texts from English Wikipedia, is employed as a raw encoder,
unbiased into any downstream NLP task but just the Masked Language Modeling (MLM) and
Next Sentence Prediction (NSP).
A second encoding for tweets was learned by Twitter-roBERTa-base for Irony Detection [23]
(irony encoding). This model was fine-tuned into the Irony Detection task, by employing the
training dataset from Task 3A at SemEval-2018: “Irony Detection in English Tweets”. With
this representation, we aim to capture abstract features that the model relies on for classifying
whether a tweet is ironic, which is a key matter for the studied AP task.
Finally, we also include the encodings learned by the pre-trained LM HateXplain [24] fine-
tuned with the data from HatEval over the downstream task of classifying whether a tweet
comes hatefully undertoned (h-stereo encoding). Taking into account this dataset has the
particularity that hate is spread toward immigrants and women, and in the case of sarcastic
language generally, the speaker aims to hurt [25], we hypothesize that these encodings capture
relations regarding stereotyping and toxicity of posts.
For each case, we made use of the HuggingFace Transformers library 3 and when the fine-tuning
was carried out, we stacked to the Transformer Model (TM) an intermediate layer as a bottleneck
for extracting a representation of the input message in a latent space. This intermediate layer is
fed with the first token of the output sequence from the TM. Then, this encoding is passed to
an output neuron which makes the prediction for the targeted task.
As in [7], in the tuning phase, we employed a gradual unfreezing-discriminative setting, proposed
in the Universal Language Model Fine-tuning (ULMFiT) [26] by employing a different learning
rate for each encoder layer in the TM, increasing it while the neural network gets deeper.

3.2. Graph-based Profile Modeling
In [7] we proposed modeling the profile in terms of tweets as a graph-based structure assuming
the facts:

   (i) In social media accounts, sentiments towards a group of people, topic, or simply some
speech target are spread in a scattered manner e.g., the hateful content of an idea can be con-
structed by relating the information from different posts.

   (ii) The profiles within the data were not structured following any temporal order, which is
also aligned with our actual data.

This allowed us to share the information from one tweet (node) to the others while its in-
dividual information was being transformed to express how it belonged in its context, by
employing a Spectral Graph Convolutional Neural Network (SGN). In this graph, every node
was a tweet, and each of them was connected to the others.
Nevertheless, since a trivial complete-graph structuring was employed, no semantic relations
were considered when creating the edges between nodes. On the other hand, as the aggregation

   2
       https://yknzhu.wixsite.com/mbweb
   3
       https://huggingface.co/transformers
function we used a simple normalized and un-weighted sum of the neighbors’ information,
defined by the node-wise operator:

                                         ⎛                         ⎞
                                                 ∑︁          1
                            𝑥′𝑖 = 𝑅𝑒𝐿𝑈 ⎝Θ                 √︁      𝑥𝑗 ⎠                         (1)
                                              𝑗∈𝒩 (𝑖)∪{𝑖}    ˆ ˆ
                                                            𝑑𝑗 𝑑𝑖

Where 𝑥𝑖 represents the encoding of the 𝑖𝑡ℎ node, 𝑑𝑖 the degree of the 𝑖𝑡ℎ node, 𝒩 (𝑖) is the set
of neighbor nodes of 𝑖 and Θ is the matrix of learnable parameters (our filter) which learn the
spectral relations.

Graph Structuring
For our approach, given a profile, we propose to link a pair of nodes according to semantic
similarities captured by our raw encoder described in Section 3.1 in a 𝛽-similar graph. Afterward,
communities are isolated by the Girvan-Newman clustering algorithm [27] for the detection
and analysis of community structure.
Girvan-Newman algorithm relies on the iterative elimination of edges with the highest number
of shortest paths between nodes passing through them, i.e., their betweenness [28]. With this
connection reduction, we aim to group tweets related by topic and/or style within the same
connected component of the graph.
Once nodes are grouped, their vector representation is replaced by the aggregation of irony-
stereotyping features learned by irony and h-stereo. Over this representation, the non-necessarily
connected graph is then fed into a non-Spectral Graph Convolutional Net.

In the prior process, we first model the graph with raw node encodings because we want
to avoid grouping tweets according to biased representations into irony or stereotype infor-
mation. Instead, we want to relate tweets according to their topic and semantic information
regardless of any communicative device and style. All of this, considering how information
is transformed by the Graph ConvNet and how prototypes are selected from topic-connected
components.

Convolutional Operator
For spectral approaches like the one employed in [7], the learned filters Θ depend on the
Laplacian eigenbasis, which depends on the graph structure as can be observed in the matrix-
wise formulation of the message-passing function from [29]. Thus, a model trained on a specific
structure can not be directly applied to a graph with a different structure, causing the high
variance observed in [7] for this encoding-classification method.
In our approach, we employed the Spacial Attention-based operator from [30]. Also, this operator
in the aggregation phase, rather than making an indiscriminate summation over neighbors’
information, allows to compute the hidden representations of each node, by attending over its
neighbors following a self-attention strategy and giving them relative importance; that is:
                                            ∑︁
                                    𝑥′𝑖 =           𝑎𝑖𝑗 Θ𝑥𝑗                                 (2)
                                           𝑗∈𝒩 (𝑖)∪{𝑖}


Where 𝒩 (𝑖) is the set of nodes belonging to the neighborhood of 𝑖, Θ computes higher-level
features of the nodes encoding 𝑥𝑗 and 𝑎𝑖𝑗 corresponds to the weighting factor for node 𝑗 taking
into account the query node 𝑖. This relative importance is computed as:

                                                          𝑒𝑥𝑝(a𝑇 𝑔(Θ[𝑥𝑖 ||𝑥𝑗 ]))
           𝑎𝑖𝑗 = 𝑠𝑜𝑓 𝑡𝑚𝑎𝑥(a𝑇 𝑔(Θ[𝑥𝑖 ||𝑥𝑗 ])) =        (︁ ∑︀                            )︁       (3)
                                                  𝑒𝑥𝑝                  a 𝑇 𝑔(Θ[𝑥 ||𝑥 ])
                                                           𝑘∈𝒩 (𝑖)∪{𝑖}          𝑖   𝑘


Here, 𝑎𝑇 corresponds to a single dense-layer self-attention mechanism and 𝑔 to the non-linear
activation function, in this case, LeakyRelu.

Components Aggregation and Classification
When information within nodes has been shared and transformed according to their context,
we aggregate all the connected components’ information to approach the graph (profile) classi-
fication, for this, we explored two paradigms.

The first one was to construct for each connected component with a greedy fashion an approxi-
mation of a set of prototypes, where for any path of length 3 (𝑒1 , 𝑒2 , 𝑒3 ), there is one and just
one node belonging to this set. This construction avoids considering two nodes with separation
degrees lower than 3. Taking into account that when one message-passing step is carried out,
the nodes get informed about all their neighbors, by selecting such a set of prototypes we cover
all the information in the original components.
The graph representation is determined by the normalized summation over its prototypes and
it is considered the learned profile modeling.

The second criterion relies on conducting the minimum message-passing iterations needed to
ensure that any node has knowledge about the information of all the other nodes within its
component. Then, under this all-nodes-informed assumption, a random prototype for each
component is selected for modeling the profile as in the first approach.
Assuming the expected degree of a node within a connected component 𝐶 is ¯𝛿 and based on the
social media degrees of separation [31], the maximum expected distance between two nodes is
given by 𝑡 = ⌈log¯𝛿 |𝐶|⌉, and hence the minimum amount of needed iterations.

For both methods, the obtained profile representation is then fed into two sequentially-connected
dense layers in charge to predict the probability of a profile being an irony and stereotypes
spreader.
3.3. Two inner prototypes for a profile
As an alternative to the graph-based modeling, we propose to condense the profile information
by selecting a kernel of posts with highly-shared knowledge. This reduction in the number of
useful tweets to represent the profiles is carried out by considering that not necessarily every
post from an irony and stereotypes spreader contains relevant information regarding being
ironic or not. Hence, we aim to inhibit the probably noisy impact of non-representative tweets.

Given a profile, at first, each tweet is encoded by employing the sn-xlm-roberta-base-snli-
mnli-anli-xnli pre-trained Language Model 4 . This model, as well as the above mentioned TMs,
is based on a RoBERTa pre-training strategy but fine-tuned through a Siamese Neural Network
over Natural Language Inference (NLI) task [32].
Afterward, it is defined for a message the knowledge-sharing score as the average for its cosine
similarity with the rest of the profile’s tweets. Taking into account these scores, we make two
disjoint subsets of tweets for each profile, one containing the half (100 tweets) most knowledge-
sharing (i), whereas the other contains its complement (ii).
The first subset is then composed of tweets associated with the main ideas or content addressed
by the user, the second one can be seen as the set of tweets less representative of the profile.
Finally the embedding of the profile results from the sum of each tweet encoding from the
subset (i).
For this modeling, we classify an unknown profile as an irony and stereotypes spreader or not
using the following steps:

   1. For each profile in the training set (IROSTEREO spreader or not), obtain its embedding as
      described above (𝑘𝑒𝑖 ).
   2. Obtain the embedding for the unknown profile (𝑢𝑒 ).
   3. Compare 𝑢𝑒 with each of the embeddings 𝑘𝑒𝑖 and assign the unknown profile to the class
      of the most similar embedding (1-NN classification).

For this strategy (in 3𝑟𝑑 step), we employed cosine similarity, and we also tried to construct the
embedding with elements from (ii) rather than (i).


4. Experiments and Results
For evaluating the conducted experiments over the prior proposals, we employed a cross-
validation approach with 5-folds, taking into account the original distribution for each intro-
duced dataset. Also, we used the evaluation metrics proposed by the profiling task organizers,
the accuracy and F1-Macro for first and second subtask respectively.
As naturally, we first fine-tuned the LMs seeking a good performance in the introduced interme-
diate tasks and hence latent representations able to capture ironic and/or stereotyping features
to construct the final modelation of the whole profile.
For the stacked dense layer between the TM and the softmax classification layer refereed in
Section 3.1, we employed the ReLU non-linear activation function and optimized the models’
   4
       https://huggingface.co/symanto/sn-xlm-roberta-base-snli-mnli-anli-xnli/discussions
parameters with the RMSprop algorithm [33]. Over this configuration, we tuned the batch size,
starting learning rate with values sampled in the range [1e-5, 5e-5] and the learning rate decay,
resulting in the most stable results by employing an initial learning rate of 2e-5 and equal decay
with a batch size of 64 examples over 8 epochs, as shown in Table 1.

Table 1
Data Representation Models Results for Intermediate Tasks.
                                    Task         Model                 Accuracy
                                                 irony-encoder           0.979
                                    Irony        bertweet                0.940
                                                 bertweet-mtl            0.610
                                                 h-stereo-encoder        0.965
                                    h-stereo     bertweet                0.941
                                                 bertweet-mtl            0.730


Here, bertweet refers to a model pre-trained in general-topic tweets [34] and fine-tuned into
the corresponding task and data. It is introduced as a base model for a multitask approach
(bertweet-mtl) to unify the ironic and stereotyping features learning.
As can be observed, in both feature-learners the higher accuracy was reached by models trained
and fine-tuned within the downstream task domain, whereas the worst performance is obtained
by the multi-task approach. Hence, the more effective combination of features for each tweet
results from aggregating the ironic and stereotyping representations learned individually.

At the profile modeling stage, we tuned the 𝛽-value for constructing the 𝛽-similar graph.
The most stable constructions were obtained for 𝛽 = 0.97 , with expected node degree ¯𝛿 = 18
and expected component size ¯𝑐 = 53, above this value almost every node remained isolated,
which is equivalent to at aggregation and classification stage, making a summation over the
tweets representation. Below 0.97, the components became considerably big, yielding a modela-
tion similar to not making any grouping over style-content representations given by the LM.
Also, intuitively5 we can assume that function 𝑓 (𝛽) = ¯𝛿 , as well as 𝑔(𝛽) = ¯𝑐, is monotonically
decreasing because of the way 𝛽-similar graphs are constructed, therefore the results obtained
within a sampled and relaxed neighborhood such as [0.9, 0.99] can be extended to the whole
𝑓 -domain (𝑔-domain).
Employing this construction and after tuning the batch size, learning rate as well as the number
of hidden units for the condensation layer after the Graph Neural Net message passing, we
explored avoiding the community refining phase by the Girvan-Newman algorithm on strategies
described in Section 3.2.
Here, GreedySharing refers to the first aggregation method based on greedily selecting pro-
totypes after message passing. LogSharing, refers to the second strategy, which is based on
approaching as many sharings as needed to ensure every node to know about each other (based
on the expected node degree). Also, the * stands for the no application of the Girvan-Newman
algorithm. For all the configurations, the best results were achieved by employing a batch size
   5
       Two cases must be considered when 𝛽 increases: (i) the edges remain the same, (ii) they decrease at least by 1.
Table 2
Community Refining Results.
                                  Modelation        Accuracy
                                  GreedySharing      0.845
                                  GreedySharing*      0.833
                                  LogSharing         0.714
                                  LogSharing*         0.711



of 16, a learning rate of 2𝑒 − 3, and 32 neurons for the intermediate dense layer, and as we can
see, isolating communities and sharing their prototypes information, outperforms the accuracy
in both methods, especially for the greedy-based approach.

Finally, to compare these architectures’ results, jointly with the method described in Sec-
tion 3.3 we bring the ideas previously proposed in [7]. The latter experimental models were fed
with the latent representation learned by the intermediate layer of our Spacial Graph Network
(SGN).
Table 3
Architectures Cross-validation Results.
                                 Modelation            Accuracy
                                 GreedySharing           0.845
                                 kernel+                 0.897
                                 kernel-                 0.864
                                         Previous Works
                                 LSTM                    0.821
                                 SGN                     0.761
                                 GreedySharing+SVM       0.783
                                 GreedySharing+DIM       0.775


In Table 3 kernel+ and kernel- refers to methodologies described in Section 3.3, where tweets
with higher or lower knowledge-sharing score are taken into account for modeling the pro-
file respectively. LSTM modelation, instead considering the aggregation of irony and h-stereo
features as nodes encodings, it analyzed the profile as a sequence. GreedySharing+SVM and
GreedySharing+DIM employ the latent representation of the GreedySharing-SGN wit a SVM
and the Deep Impostor Method [7] respectively.

From here, we can see how employing information commonly shared across the tweets within
a profile outperforms our greedy prototypes aggregation through the Spacial Graph Neural
Network. Nevertheless, this approach outperforms the deep-aggregation made by the Spectral
Network and the LSTM sequential analysis.

For facing second subtask, we employed the best-performed models configurations on irony and
stereotyping spreader detection. These are kernel+ and GreadySharing strategies, achieving
0.587 and 0.581 of F1-Macro resectivelly.
Regarding the official competition results, in the unblinded submission our Graph-based mod-
elation achieved 81.1% of accuracy under the test dataset for the first subtask, showing an
important variance-issue reduction w.r.t. the method proposed in last year’s competition.
Hence, increasing the model size would be a reasonable way to squeeze the biased scenario
shown by cross-validation results taking into account the proposed kernel-based method. For
the second subtask, we were allowed to make two submissions achieving 0.4886 and 0.4685 of
F1-Macro for kernel+ and GreadySharing strategies respectively.


5. Conclusions and Future Works
In this paper, we described two systems for addressing the task shared on PAN 2022: “Profiling
Irony and Stereotype Spreaders on Twitter”. The first approach relies on a 𝛽-similar graph
construction for each profile, whose nodes represent the tweets within the account, encoded as a
combination of irony and stereotyping-related features. The graph’s information is propagated
through a Spacial Attention-based Graph Neural Network and prototype nodes are selected and
aggregated to classify the profile with a Feed-forward Neural Net.
The second approach is supported by a profile reduction, under the assumption that given an
ironic profile, non-ironic tweets may introduce some noise at the classification stage. Firstly,
the tweets are encoded and compared for determining a knowledge-sharing score. Afterward,
the highest scored tweets are selected as prototypes and aggregated, taking into account that
containing highly employed contextual/stylistic abstract features indicates a particular behavior
of users. Finally, an unknown profile is classified with the label of its more similar aggregation
from the training set.
Experimental results show our graph-based model outperforms the combination of its latent
representation with another meta-classifier, especially the Deep Impostor Method (DIM) pro-
posed in [7]. The latter solves two issues; (i) sensible hyper-parameter selection for DIM, and (ii)
the high variance observed with previously graph-based architecture. On the other hand, the
approach based on profile reduction achieved even better results, which indicates that effectively
some elements may result in noise when modeling and classifying the profile.
Since the new construction of the graph and its analysis paradigm (spacial instead of spec-
tral) achieved competitive results with the kernel-based method, besides 𝛽-similar graphs still
looking as a natural way to represent profile information, we plan to introduce the reduction
schema described in Section 3.3. Also, for constructing the initial graph instead the raw encoder,
employing a more similarity-oriented pre-trained LM as sn-xlm-roberta-base-snli-mnli-anli-xnli
from Section 3.3, would yield a more robust graph structure. Finally, since the optimizing
problem is now the bias reduction instead of the variance of the model, introducing a bigger
architecture, possibly by using a more complex aggregation function, would help to this end.


Acknowledgments
This work was supported by projects PLEC2021-007662 (MCIN/AEI/10.13039/501100011033,
Ministerio de Ciencia e Innovación, Agencia Estatal de Investigación, Plan de Recuperación,
Transformación y Resiliencia, Unión Europea-Next Generation EU) and RTI2018-093336-B-C22
(Ministerio de Ciencia e Innovación, Agencia Estatal de Investigación). The second author also
thanks the financial support supplied by the Consellería de Cultura, Educación e Universidade
(GPC ED431B 2022/33)


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