Impact of Membership Function Design on Grammatical Acceptability in Fuzzy Grammar Models

Authors

  • Thomas Rihonggao

    Telecommunication Engineering Study Program, School of Electrical Engineering, Telkom University, Bandung 40257, Indonesia
  • Rustam

    Telecommunication Engineering Study Program, School of Electrical Engineering, Telkom University, Bandung 40257, Indonesia

    Center of Excellence for Strategic Advancement for Key Digital Transformation Indonesia, Research Institute for Intelligent Business and Sustainable Economy, Telkom University, Bandung 40257, Indonesia

DOI:

https://doi.org/10.30564/fls.v7i11.11518
Received: 6 August 2025 | Revised: 20 August 2025 | Accepted: 3 September 2025 | Published Online: 28 October 2025

Abstract

Grammatical acceptability, the extent to which a sentence conforms to the structural and usage norms of a language, has long been recognized as a gradient phenomenon rather than a binary distinction. Linguistic research on gradient grammaticality has examined how factors such as syntactic configuration, word order, and clause integration influence native speaker judgments. This study adopts a fuzzy grammar framework to model such gradience and investigates how the design of membership functions influences the evaluation of sentence acceptability. A curated dataset of five English sentences was selected to represent a range of linguistic structures, including canonical declaratives, syntactic inversion, passive voice, and clausal subordination. For each sentence, rule-based violation scores were assigned for three linguistic dimensions: subject–verb agreement, phrase structure and word order, and clause integration and cohesion. Four types of membership functions, Linear, Sigmoid, Gaussian, and Trapezoidal, were applied to transform these scores into fuzzy membership degrees, which were then aggregated into overall acceptability judgments. Results reveal that while the relative ranking of sentences by acceptability remains stable across functions, the absolute scores vary substantially, with Gaussian producing the most conservative evaluations and Trapezoidal yielding plateau effects. These differences have direct implications for how fuzzy models capture subtle linguistic variation and for the interpretability of computational tools used in grammaticality assessment. The findings highlight the necessity of treating membership function selection as a theoretically motivated decision in fuzzy linguistic modeling, thereby contributing to more transparent and linguistically grounded applications in both theoretical and applied language studies.

Keywords:

Fuzzy Grammar; Fuzzy Logic; Grammatical Acceptability; Interpretability; Linguistic Modeling; Membership Function Design; Natural Language Processing; Rule-Based Evaluation

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How to Cite

Rihonggao, T., & Rustam. (2025). Impact of Membership Function Design on Grammatical Acceptability in Fuzzy Grammar Models. Forum for Linguistic Studies, 7(11), 1491–1507. https://doi.org/10.30564/fls.v7i11.11518

Issue

Vol. 7 , Iss. 11 (November 2025)

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Article

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Copyright © 2025 Thomas Rihonggao, Rustam

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This is an open access article under the Creative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0) License.