Cited by 2Sentiment Analysis and Opinion MiningEmotion and Mood RecognitionTopic Modeling

Emotion Classification With Visibility Graphs

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Şimşek, Ecem, Topcu, Atakan, Koç, Emirhan, Saritas, Emine Ulku, Koç, Aykut·2025·IEEE Signal Processing Letters

Abstract

Transformers have gained prominence in natural language processing due to their representational capabilities and performances. Transformers process natural language as a sequence on finite context windows; however, global relationships among words beyond these windows cannot be completely modeled via sequence processing only. Graph neural network (GNN) based models have been proposed to alleviate this problem, as they provide geometric extensions to neural networks, enabling models to learn associations within a text. However, regular graph-based methods ignore the sequential nature of underlying texts. In this paper, we propose EmoVis, the first generic graph-based neural network that utilizes visibility graphs, which converts classical time-series information to graph representations. We cast the problem as an emotion classification task, enabling the proposed model to learn associations between the labels and words in a sentence. Moreover, EmoVis can be used as a highly modular graph-based extension to any transformer-based model, significantly improving their performance and learning capabilities in various languages. We experimentally show that EmoVis enables transformer-based models to outperform the state-of-the-art baselines across three diverse datasets in different languages in the SemEval2018 competition datasets and the GoEmotions dataset.

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AI snapshot

Written from the paper’s full text.

TL;DR

EmoVis is a modular visibility-graph/GCN extension for transformer-based multi-label emotion classification that preserves sentence order via directed vector visibility graphs. It improves transformer models and reportedly outperforms state-of-the-art baselines on SemEval2018 English/Arabic/Spanish and GoEmotions.

Key findings

  • EmoVis schemes consistently improve F1-Macro, F1-Micro, and Jaccard index (JS) for each tested transformer model on the SemEval2018 MLEC tasks; EmoVis_lin boosts vanilla models’ F1-Micro scores by up to 4.28%.
  • The paper presents EmoVis as the first generic graph-based model using visibility graphs for MLEC across languages, and as a plug-in that can enhance any transformer-based model.
  • SemEval2018 languages all have 11 emotion classes; GoEmotions has 28 emotion classes, and EmoVis_lin is reported to improve transformer performance on GoEmotions, with full details in the Supplementary Material.
  • The abstract claims EmoVis enables transformer-based models to outperform state-of-the-art baselines across three diverse datasets in different languages in SemEval2018 and the GoEmotions dataset.

Methods

  • Sentences are preprocessed/tokenized, passed through a transformer encoder (TwHIN-BERT-Base) to produce contextual embeddings \(X_{BERT} \in \mathbb{R}^{N \times M}\); each token vector becomes a node in a directed vector visibility graph (VVG) using projection-based visibility, then normalized node embeddings and adjacency matrices are fed to a GCN with SAGEConv, ReLU, batch normalization, global max pooling, dropout, and a linear layer.
  • Three integration schemes—EmoVis_lin, EmoVis_nonlin, EmoVis_concat—combine graph and transformer outputs with interpolation coefficient \(\lambda\), apply sigmoid, and threshold at 0.5; training uses label-correlation aware (LCA) loss.
  • Experiments use SemEval2018 English/Arabic/Spanish (11 emotion classes) and GoEmotions (28 classes); fine-tuned models include TwHIN-BERT-Base, BERT-Base variants, RoBERTa-Base (English only), and XLM-RoBERTa-Base; Adam optimizer with learning rate 1.421e-3, batch size 58, 20/18/16 epochs for English/Arabic/Spanish, dropout 0.1675, hidden channel size 128, context window 128; metrics are Micro F1, macro F1, and Jaccard index.

Limitations

  • The paper does not include an explicit limitations section.
  • The paper states the context window is set to 128 to balance performance with computational efficiency, which bounds the modeled context.
  • Evident from the text: full analyses of standalone EmoVis, parameter counts, ablations with state-of-the-art plug-in models, interpolation coefficients, GoEmotions results, and comparisons of graph convolution layers are deferred to the Supplementary Material, so the main text does not provide those details; the provided text also references Table I but does not include the table itself, so exact per-model/per-language scores cannot be verified from the supplied text.

Model-written summary. Check it against the paper before relying on it.

Integrity signals

Registry

Crossref · 10.1109/lsp.2025.3567033

Cites

54 of 54 references verified0 citation errors · 0 not checkable

Statistics

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Claims the paper makes

20 of 26 cited sources checked · 8 supported · 0 flagged · accuracy not yet measured

  • Premisecitation

    Integrating external domain knowledge into emotion recognition models is usually a complex and time-consuming process.

    “However, integrating external domain knowledge into emotion recognition models is usually a complex and timeconsuming process [19].”
    Quote in the paperSubstantial claim1 of 1 sources checked
    • cites [19] source

      The Introduction (‘Focus of the paper’; page not provided) describes increasing complexity in ways of incorporating domain knowledge, and ‘Challenges and concluding remarks’ identifies technical difficulties. The passages do not establish that integration is usually time-consuming or address emotion recognition models specifically. (LLM, conf=0.84)

      Experimental — accuracy not yet measured
  • Premisecitation

    Visibility graphs offer an effective means of representing sequential signals by connecting data points according to their value-based visibility, thereby preserving the underlying temporal structure while introducing geometric relationships.

    “To this end, visibility graphs offer an effective means of representing sequential signals by connecting data points according to their value-based visibility, thereby preserving the underlying temporal structure while introducing geometric relationships [22], [23].”
    Quote in the paperSubstantial claim1 of 2 sources checked
    • cites [22] source
    • cites [23] source
  • Premisecitation

    Incorporating a significant number of graph convolution layers in network architectures can result in over-smoothing of dataset features, thereby diminishing the performance of the training process.

    “As for the GNN-based approaches, incorporating a significant number of graph convolution layers in network architectures can result in over-smoothing of dataset features, thereby diminishing the performance of the training process [20].”
    Quote in the paperSubstantial claim1 of 1 sources checked
  • Interpretationcitation

    EmoVis captures semantic relations previously not emphasized by existing sequential models.

    “It also captures semantic relations previously not emphasized by existing sequential models [28], [29].”
    Quote in the paperSubstantial claim1 of 2 sources checked
    • cites [28] source

      The Introduction says GNNs capture relations between graph nodes, and Section 3.1 describes BertGCN using graph structure to update document representations. The paper does not assess EmoVis or establish that existing sequential models neglect the semantic relations claimed here. (LLM, conf=0.80)

      Experimental — accuracy not yet measured
    • cites [29] Michel, 2019, Are sixteen heads really better than one? source
  • Premisecitation

    GCNs primarily focus on local graph structures, which restricts their ability to utilize global context within graphs fully.

    “Furthermore, GCNs primarily focus on local graph structures, which restrict their ability to utilize global context within graphs fully [20].”
    Quote in the paperSubstantial claim1 of 1 sources checked
  • Classified as probably not a substantial claim. 9
  • May combine two claims. 7
  • Classified as probably not a substantial claim.

    Premisecitation

    The vector visibility graph (VVG) algorithm extends the univariate visibility graph concept to multivariate time series data.

    “The vector visibility graph (VVG) algorithm [25] extends the univariate visibility graph [22], [24] concept to multivariate time series data”
    Quote in the paperSubstantial claim2 of 3 sources checked
    • cites [25] source
    • cites [22] source
    • cites [24] source
  • May combine two claims.

    Premisecitation

    Transformers process natural language as a sequence on finite context windows, and global relationships among words beyond these windows cannot be completely modeled via sequence processing only.

    “Transformers process natural language as a sequence on finite context windows; however, global relationships among words beyond these windows cannot be completely modeled via sequence processing only.”
    • Also stated in: § Abstract · plain
      “More specifically, sequential models process text as token sequences within fixed context windows, limiting their ability to capture word-level dependencies that span beyond those boundaries [12], [13].”
    Quote in the paperSubstantial claim2 of 2 sources checked
    • cites [12] source

      The Introduction says Transformer language models have maximum sequence lengths and that small context windows prevent models from using long-range discourse structure. The Conclusion reports that the two models studied rarely take advantage of long-range context. The paper does not establish the broader claim that sequence processing alone cannot completely model relationships beyond a window. (LLM, conf=0.85)

      Experimental — accuracy not yet measured
    • cites [13] source

      Section 5 (page not available in our copy) reports that the LSTM language model has a limited effective context and becomes less sensitive to word order farther back. The paper studies LSTMs, not Transformers, and does not establish that sequence processing cannot completely model relationships beyond a finite window. (LLM, conf=0.85)

      Experimental — accuracy not yet measured
  • Probably not a substantial claim: may not pass S2 (checkable).

    Interpretationcitation

    The challenges in capturing relationships and dependencies among emotions indicate the necessity for an architecture that is both easy to construct and preserves the structure of the underlying signal in its topology to improve both performance and interpretability.

    “The challenges in capturing relationships and dependencies among emotions indicate the necessity for an architecture that is both easy to construct and preserves the structure of the underlying signal in its topology to improve both performance and interpretability [21], [22].”
    Quote in the paperNot a substantial claim2 of 2 sources checked
    • cites [21] Horn, 2022, Topological graph neural networks source

      Split into 2 atoms — 0 confirmed, 2 partially supported, 0 disputed, 0 misattributed, 0 unverifiable. Expand the claim to see per-atom verdicts.

      Experimental — accuracy not yet measured
    • cites [22] source

      Split into 2 atoms — 0 confirmed, 2 partially supported, 0 disputed, 0 misattributed, 0 unverifiable. Expand the claim to see per-atom verdicts.

      Experimental — accuracy not yet measured
  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    In VVG, edge directionality stems from the projection-based asymmetry between multidimensional vectors; when M = 1, vectors reduce to scalars, eliminating projections and making visibility symmetric, resulting in an undirected graph.

    “In VVG, edge directionality stems from the projection-based asymmetry between multidimensional vectors.When M = 1, vectors reduce to scalars, eliminating projections and making visibility symmetric, resulting in an undirected graph [22], [25].”
    Quote in the paperNot a substantial claim1 of 2 sources checked
    • cites [22] source

      The visibility-algorithm description (Resumen, p. 1) says that a graph built from scalar time-series values is undirected because its links have no defined direction. It does not discuss VVG, multidimensional vectors, M = 1, or projection-based asymmetry as the reason directionality disappears. Its discussion of a possible directed graph instead relates direction to the temporal axis (Resumen, p. 6). (LLM, conf=0.87)

      Experimental — accuracy not yet measured
    • cites [25] source
  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    The natural visibility graph (NVG) algorithm is a foundational method for mapping univariate (scalar) time series into graph networks.

    “The natural visibility graph (NVG) algorithm [22] is a foundational method for mapping univariate (scalar) time series into graph networks.”
    Quote in the paperNot a substantial claim1 of 1 sources checked
  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    The visibility graph transformation supports both scalar and vector representations, with applications spanning time series analysis and language processing.

    “This simple yet versatile transformation supports both scalar [22], [24] and vector representations [25], with applications spanning time series analysis and language processing [26], [27].”
    Quote in the paperNot a substantial claim2 of 3 sources checked
    • cites [22] source
    • cites [24] source
    • cites [25] source
  • Probably not a substantial claim: may not pass S4 (based).

    Interpretationnone given

    The model-agnostic and modular nature of EmoVis, with its low complexity and streamlined set of hyperparameters, facilitates easy integration with other models across various languages to increase their performance.

    “Additionally, the model-agnostic and modular nature of the EmoVis, with its low complexity and streamlined set of hyperparameters, facilitates easy integration with other models across various languages to increase their performance.”
    Quote in the paperNot a substantial claim
    • Rests on an assumption: The SemEval2018 and GoEmotions datasets and their partitions are suitable and representative for evaluating multilingual multi-label emotion classification.
  • May combine two claims.

    Interpretationreasoning

    EmoVis implements an advanced pooling strategy involving graph-based message passing followed by maximum pooling for classification, offering a significant improvement over standard transformer models solely relying on [CLS] or pooled tokens.

    “This approach allows EmoVis to implement an advanced pooling strategy involving graph-based message passing followed by maximum pooling for classification, offering a significant improvement over standard transformer models solely relying on [CLS] or pooled tokens.”
    Quote in the paperSubstantial claim
    • Rests on an assumption: The order of token embeddings in a transformer output can be treated as a time series whose visibility graph captures meaningful sequential and semantic relationships for emotion classification.
  • May combine two claims.

    Interpretationown data

    EmoVis can be used as a highly modular graph-based extension to any transformer-based model, significantly improving their performance and learning capabilities in various languages.

    “Moreover, EmoVis can be used as a highly modular graph-based extension to any transformer-based model, significantly improving their performance and learning capabilities in various languages.”
    • Also stated in: § IV. CONCLUSION · plain
      “Additionally, the model-agnostic and modular nature of the EmoVis, with its low complexity and streamlined set of hyperparameters, facilitates easy integration with other models across various languages to increase their performance.”
    Quote in the paperSubstantial claim
    • Rests on an assumption: The SemEval2018 and GoEmotions datasets and their partitions are suitable and representative for evaluating multilingual multi-label emotion classification.
  • Classified as probably not a substantial claim. May combine two claims.

    Premisereasoning

    GNN-based models provide geometric extensions to neural networks, enabling models to learn associations within a text, and have been proposed to alleviate the problem of limited context modeling.

    “Graph neural network (GNN) based models have been proposed to alleviate this problem, as they provide geometric extensions to neural networks, enabling models to learn associations within a text.”
    Quote in the paperSubstantial claim
  • Probably not a substantial claim: may not pass S2 (checkable), S3 (load-bearing), S4 (based).

    Interpretationnone given

    EmoVis is easy to construct.

    “EmoVis (Emotion Classification with Visibility Graphs), a novel, highly modular graph-based model that preserves the topology of the input sentence, is easy to construct, and, most importantly, improves the performance of any transformer-based model to which it is added.”
    Quote in the paperNot a substantial claim
  • May combine two claims.

    Interpretationreasoning

    EmoVis effectively captures complex representations overlooked by traditional deep learning models by maintaining the temporal sequence of text and recognizing patterns through its directed node connections.

    “EmoVis effectively captures complex representations overlooked by traditional deep learning models by maintaining the temporal sequence of text and recognizing patterns through its directed node connections.”
    Quote in the paperSubstantial claim
    • Rests on an assumption: The order of token embeddings in a transformer output can be treated as a time series whose visibility graph captures meaningful sequential and semantic relationships for emotion classification.
  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductnone given

    The experiments used a fixed initialization seed.

    “We used a fixed initialization seed.”
    Quote in the paperNot a substantial claim
13 of 13
  • The paper relies on this without support.

    The SemEval2018 and GoEmotions datasets and their partitions are suitable and representative for evaluating multilingual multi-label emotion classification.

    “We primarily utilize the SemEval2018 Twitter multilingual multi-class multi-label dataset [9], the most common MLEC task benchmark.”
    “We use the respective languages' same Train/Valid/Test partitions.”
  • The paper relies on this without support.

    The baseline performances taken from the literature are directly comparable to the paper's experimental setup and results.

    “The performances of these baselines on the SemEval2018 benchmark are taken directly from the corresponding literature.”
  • The paper relies on this without support.

    The order of token embeddings in a transformer output can be treated as a time series whose visibility graph captures meaningful sequential and semantic relationships for emotion classification.

    “EmoVis represents sentences as graph-based time series using high-dimensional embeddings on graph nodes.”
    “each vector in the sequence X BERT ∈ R N ×M is treated as a node within the VVG structure”
3 of 3

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Authors
Şimşek, E., Topcu, A., Koç, E., Saritas, E. U., & Koç, A.
Affiliations
  • Bilkent University (TR)
  • Department of Electrical and Electronics Engineering, Bilkent University, Ankara, Türkiye
Venue
IEEE Signal Processing Letters
Published
2025
Volume
32
Pages
2055-2059
ISSN
  • 1070-9908 (ISSN-L)
  • 1558-2361
OpenAlex
W4410086475
Cited by
2
References
48
Citations by year
2026: 1 · 2025: 1
FWCI
0.82
Type
journal article
Language
en
Open access
Locations
  • IEEE Signal Processing Letters (publishedVersion)
  • Bilkent University Institutional Repository (Bilkent University) (submittedVersion, cc-by)
Funders
  • BAGEP Award of the Science Academy (124E179)
  • Communication Technologies Authority
  • Scientific and Technological Research Council (5249902)
Topics
  • Physical Sciences › Computer Science › Artificial Intelligence › Sentiment Analysis and Opinion Mining
  • Social Sciences › Psychology › Experimental and Cognitive Psychology › Emotion and Mood Recognition
  • Physical Sciences › Computer Science › Artificial Intelligence › Topic Modeling
Keywords
emotion classification, visibility graph, graph neural networks, transformer models, text representation, GoEmotions

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