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Tahmasebi, S., Hamad, M., Payberah, A. H. & Matskin, M. (2026). PureBiasoMeter: Decoupling Popularity Bias from User Fairness in LLM-Based Recommender Systems. In: Recommender Systems for Sustainability and Social Good - Second International Workshop, RecSoGood 2025, Proceedings: . Paper presented at 2nd International Workshop on Recommender Systems for Sustainability and Social Good, RecSoGood 2025, Prague, Czechia, September 26, 2025 (pp. 155-168). Springer Science and Business Media Deutschland GmbH
Open this publication in new window or tab >>PureBiasoMeter: Decoupling Popularity Bias from User Fairness in LLM-Based Recommender Systems
2026 (English)In: Recommender Systems for Sustainability and Social Good - Second International Workshop, RecSoGood 2025, Proceedings, Springer Science and Business Media Deutschland GmbH , 2026, p. 155-168Conference paper, Published paper (Refereed)
Abstract [en]

Large Language Models (LLMs) have transformed Recommendation Systems (RecSys) by enabling more user-aware interactions. However, this shift raises new challenges in evaluating fairness, particularly due to confounding systemic biases such as popularity bias. Conventional fairness assessments often confuse disparities in user treatment with systemic biases toward popular items, resulting in misleading conclusions. In this paper, we introduce PureBiasoMeter, a diagnostic framework that decouples popularity bias from user-level fairness in LLM-based RecSys. Our approach is based on the hypothesis that accurate fairness evaluation requires first mitigating popularity bias and then remeasuring fairness metrics. We generate a comprehensive set of 72 prompts using different user profiling strategies, demographic variants, and bias mitigation instructions. By applying these prompts in a black-box LLM setting, we evaluate fairness sensitivity, recommendation quality, and bias levels across multiple dimensions. Our results demonstrate that removing popularity bias substantially alters fairness measurements and reveals underlying disparities that were previously unknown. PureBiasoMeter thus provides a more reliable basis for fairness analysis and contributes a practical tool for disentangling intertwined sources of bias in modern RecSys.

Place, publisher, year, edition, pages
Springer Science and Business Media Deutschland GmbH, 2026
Keywords
Large Language Models, Popularity Bias, Recommendation Systems, User Fairness
National Category
Computer Sciences
Identifiers
urn:nbn:se:kth:diva-376718 (URN)10.1007/978-3-032-13342-7_14 (DOI)2-s2.0-105028087664 (Scopus ID)
Conference
2nd International Workshop on Recommender Systems for Sustainability and Social Good, RecSoGood 2025, Prague, Czechia, September 26, 2025
Note

Part of ISBN 9783032133410

QC 20260218

Available from: 2026-02-18 Created: 2026-02-18 Last updated: 2026-02-18Bibliographically approved
Khan, A. Q., Nikolov, N., Matskin, M., Prodan, R., Bussler, C., Roman, D. & Soylu, A. (2024). A Taxonomy for Cloud Storage Cost. In: Management of Digital EcoSystems - 15th International Conference, MEDES 2023, Revised Selected Papers: . Paper presented at 15th International Conference on Management of Digital, MEDES 2023, Heraklion, Greece, May 5 2023 - May 7 2023 (pp. 317-330). Springer Nature
Open this publication in new window or tab >>A Taxonomy for Cloud Storage Cost
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2024 (English)In: Management of Digital EcoSystems - 15th International Conference, MEDES 2023, Revised Selected Papers, Springer Nature , 2024, p. 317-330Conference paper, Published paper (Refereed)
Abstract [en]

The cost of using cloud storage services is complex and often an unclear structure, while it is one of the important factors for organisations adopting cloud storage. Furthermore, organisations take advantage of multi-cloud or hybrid solutions to combine multiple public and/or private cloud service providers to avoid vendor lock-in, achieve high availability and performance, optimise cost, etc. This complicated ecosystem makes it even harder to understand and manage cost. Therefore, in this paper, we provide a taxonomy of cloud storage cost in order to provide a better understanding and insights on this complex problem domain.

Place, publisher, year, edition, pages
Springer Nature, 2024
Keywords
Cloud, StaaS, Storage cost, Taxonomy
National Category
Computer and Information Sciences
Identifiers
urn:nbn:se:kth:diva-350571 (URN)10.1007/978-3-031-51643-6_23 (DOI)001260534100023 ()2-s2.0-85189635557 (Scopus ID)
Conference
15th International Conference on Management of Digital, MEDES 2023, Heraklion, Greece, May 5 2023 - May 7 2023
Note

Part of ISBN 9783031516429

QC 20240718

Available from: 2024-07-18 Created: 2024-07-18 Last updated: 2024-09-05Bibliographically approved
Khan, A. Q., Matskin, M., Prodan, R., Bussler, C., Roman, D. & Soylu, A. (2024). Cloud storage cost: a taxonomy and survey. World wide web (Bussum), 27(4), Article ID 36.
Open this publication in new window or tab >>Cloud storage cost: a taxonomy and survey
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2024 (English)In: World wide web (Bussum), ISSN 1386-145X, E-ISSN 1573-1413, Vol. 27, no 4, article id 36Article in journal (Refereed) Published
Abstract [en]

Cloud service providers offer application providers with virtually infinite storage and computing resources, while providing cost-efficiency and various other quality of service (QoS) properties through a storage-as-a-service (StaaS) approach. Organizations also use multi-cloud or hybrid solutions by combining multiple public and/or private cloud service providers to avoid vendor lock-in, achieve high availability and performance, and optimise cost. Indeed cost is one of the important factors for organizations while adopting cloud storage; however, cloud storage providers offer complex pricing policies, including the actual storage cost and the cost related to additional services (e.g., network usage cost). In this article, we provide a detailed taxonomy of cloud storage cost and a taxonomy of other QoS elements, such as network performance, availability, and reliability. We also discuss various cost trade-offs, including storage and computation, storage and cache, and storage and network. Finally, we provide a cost comparison across different storage providers under different contexts and a set of user scenarios to demonstrate the complexity of cost structure and discuss existing literature for cloud storage selection and cost optimization. We aim that the work presented in this article will provide decision-makers and researchers focusing on cloud storage selection for data placement, cost modelling, and cost optimization with a better understanding and insights regarding the elements contributing to the storage cost and this complex problem domain.

Place, publisher, year, edition, pages
Springer, 2024
Keywords
Cloud storage, Cost optimization, Cost taxonomy, Hybrid cloud, Multi-cloud, Storage-as-a-Service
National Category
Computer and Information Sciences
Identifiers
urn:nbn:se:kth:diva-347292 (URN)10.1007/s11280-024-01273-4 (DOI)001232370800001 ()2-s2.0-85194288566 (Scopus ID)
Note

QC 20240612

Available from: 2024-06-10 Created: 2024-06-10 Last updated: 2024-06-12Bibliographically approved
Khan, A. Q., Matskin, M., Prodan, R., Bussler, C., Roman, D. & Soylu, A. (2024). Cloud storage tier optimization through storage object classification. Computing, 106(11), 3389-3418
Open this publication in new window or tab >>Cloud storage tier optimization through storage object classification
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2024 (English)In: Computing, ISSN 0010-485X, E-ISSN 1436-5057, Vol. 106, no 11, p. 3389-3418Article in journal (Refereed) Published
Abstract [en]

Cloud storage adoption has increased over the years given the high demand for fast processing, low access latency, and ever-increasing amount of data being generated by, e.g., Internet of Things applications. In order to meet the users’ demands and provide a cost-effective solution, cloud service providers offer tiered storage; however, keeping the data in one tier is not cost-effective. In this respect, cloud storage tier optimization involves aligning data storage needs with the most suitable and cost-effective storage tier, thus reducing costs while ensuring data availability and meeting performance requirements. Ideally, this process considers the trade-off between performance and cost, as different storage tiers offer different levels of performance and durability. It also encompasses data lifecycle management, where data is automatically moved between tiers based on access patterns, which in turn impacts the storage cost. In this respect, this article explores two novel classification approaches, rule-based and game theory-based, to optimize cloud storage cost by reassigning data between different storage tiers. Four distinct storage tiers are considered: premium, hot, cold, and archive. The viability and potential of the proposed approaches are demonstrated by comparing cost savings and analyzing the computational cost using both fully-synthetic and semi-synthetic datasets with static and dynamic access patterns. The results indicate that the proposed approaches have the potential to significantly reduce cloud storage cost, while being computationally feasible for practical applications. Both approaches are lightweight and industry- and platform-independent.

Place, publisher, year, edition, pages
Springer Nature, 2024
Keywords
68M11, 68M14, 68T09, Cloud computing, Cloud storage, Cost optimization, StaaS, Storage cost, Storage tiers
National Category
Communication Systems
Identifiers
urn:nbn:se:kth:diva-366348 (URN)10.1007/s00607-024-01281-2 (DOI)001196187100001 ()2-s2.0-85189651806 (Scopus ID)
Note

QC 20250707

Available from: 2025-07-07 Created: 2025-07-07 Last updated: 2025-07-07Bibliographically approved
Khan, A. Q., Matskin, M., Prodan, R., Bussler, C., Roman, D. & Soylu, A. (2024). Cost modelling and optimisation for cloud: a graph-based approach. Journal of Cloud Computing: Advances, Systems and Applications, 13(1), Article ID 147.
Open this publication in new window or tab >>Cost modelling and optimisation for cloud: a graph-based approach
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2024 (English)In: Journal of Cloud Computing: Advances, Systems and Applications, E-ISSN 2192-113X, Vol. 13, no 1, article id 147Article in journal (Refereed) Published
Abstract [en]

Cloud computing has become popular among individuals and enterprises due to its convenience, scalability, and flexibility. However, a major concern for many cloud service users is the rising cost of cloud resources. Since cloud computing uses a pay-per-use model, costs can add up quickly, and unexpected expenses can arise from a lack of visibility and control. The cost structure gets even more complicated when working with multi-cloud or hybrid environments. Businesses may spend much of their IT budget on cloud computing, and any savings can improve their competitiveness and financial stability. Hence, an efficient cloud cost management is crucial. To overcome this difficulty, new approaches and tools are being developed to provide greater oversight and command over cloud a graph-based approach for modelling cost elements and cloud resources and a potential way to solve the resulting constraint problem of cost optimisation. In this context, we primarily consider utilisation, cost, performance, and availability. The proposed approach is evaluated on three different user scenarios, and results indicate that it could be effective in cost modelling, cost optimisation, and scalability. This approach will eventually help organisations make informed decisions about cloud resource placement and manage the costs of software applications and data workflows deployed in single, hybrid, or multi-cloud environments.

Place, publisher, year, edition, pages
Springer Nature, 2024
Keywords
Cloud computing, Cost optimisation, Cost modelling, Graph theory, Resource placement
National Category
Computer Sciences
Identifiers
urn:nbn:se:kth:diva-354788 (URN)10.1186/s13677-024-00709-6 (DOI)001322682600002 ()2-s2.0-85205680039 (Scopus ID)
Note

QC 20241015

Available from: 2024-10-15 Created: 2024-10-15 Last updated: 2024-10-15Bibliographically approved
Layegh, A., Payberah, A. H. & Matskin, M. (2024). REA: Refine-Estimate-Answer Prompting for Zero-Shot Relation Extraction. In: Natural Language Processing and Information Systems - 29th International Conference on Applications of Natural Language to Information Systems, NLDB 2024, Proceedings: . Paper presented at 29th International Conference on Natural Language and Information Systems, NLDB 2024, Turin, Italy, Jun 25 2024 - Jun 27 2024 (pp. 301-316). Springer Nature
Open this publication in new window or tab >>REA: Refine-Estimate-Answer Prompting for Zero-Shot Relation Extraction
2024 (English)In: Natural Language Processing and Information Systems - 29th International Conference on Applications of Natural Language to Information Systems, NLDB 2024, Proceedings, Springer Nature , 2024, p. 301-316Conference paper, Published paper (Refereed)
Abstract [en]

Zero-shot relation extraction (RE) presents the challenge of identifying entity relationships from text without training on those specific relations. Despite significant advancements in natural language processing by applying large language models (LLMs), their application to zero-shot RE remains less effective compared to traditional models that fine-tune smaller pre-trained language models. This limitation is attributed to insufficient prompting strategies that fail to leverage the full capabilities of LLMs for zero-shot RE, considering the intrinsic complexities of the RE task. A compelling question is whether LLMs can address complex tasks, such as RE, by decomposing them into more straightforward, distinct tasks that are easier to manage and solve individually. We propose the Refine-Estimate-Answer (REA) approach to answer this question. This multi-stage prompting strategy of REA decomposes the RE task into more manageable subtasks and applies iterative refinement to guide LLMs through the complex reasoning required for accurate RE. Our research validates the effectiveness of REA through comprehensive testing across multiple public RE datasets, demonstrating marked improvements over existing LLM-based frameworks. Experimental results on the FewRel, Wiki-ZSL, and TACRED datasets show that our proposed approach significantly boosts the vanilla prompting F1 scores by 31.57, 19.52, and 15.39, respectively, thereby outperforming the performance of state-of-the-art LLM-based methods.

Place, publisher, year, edition, pages
Springer Nature, 2024
Keywords
Large Language Models, Prompting Strategy, Relation Extraction
National Category
Natural Language Processing
Identifiers
urn:nbn:se:kth:diva-354657 (URN)10.1007/978-3-031-70239-6_21 (DOI)001331199300021 ()2-s2.0-85205393225 (Scopus ID)
Conference
29th International Conference on Natural Language and Information Systems, NLDB 2024, Turin, Italy, Jun 25 2024 - Jun 27 2024
Note

Part of ISBN 9783031702389]

QC 20241010

Available from: 2024-10-09 Created: 2024-10-09 Last updated: 2025-12-08Bibliographically approved
Layegh, A., Payberah, A. H., Soylu, A., Roman, D. & Matskin, M. (2024). Wiki-based Prompts for Enhancing Relation Extraction using Language Models. In: 39th Annual ACM Symposium on Applied Computing, SAC 2024: . Paper presented at 39th Annual ACM Symposium on Applied Computing, SAC 2024, Avila, Spain, Apr 8 2024 - Apr 12 2024 (pp. 731-740). Association for Computing Machinery (ACM)
Open this publication in new window or tab >>Wiki-based Prompts for Enhancing Relation Extraction using Language Models
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2024 (English)In: 39th Annual ACM Symposium on Applied Computing, SAC 2024, Association for Computing Machinery (ACM) , 2024, p. 731-740Conference paper, Published paper (Refereed)
Abstract [en]

Prompt-tuning and instruction-tuning of language models have exhibited significant results in few-shot Natural Language Processing (NLP) tasks, such as Relation Extraction (RE), which involves identifying relationships between entities within a sentence. However, the effectiveness of these methods relies heavily on the design of the prompts. A compelling question is whether incorporating external knowledge can enhance the language model's understanding of NLP tasks. In this paper, we introduce wiki-based prompt construction that leverages Wikidata as a source of information to craft more informative prompts for both prompt-tuning and instruction-tuning of language models in RE. Our experiments show that using wiki-based prompts enhances cutting-edge language models in RE, emphasizing their potential for improving RE tasks. Our code and datasets are available at GitHub 1

Place, publisher, year, edition, pages
Association for Computing Machinery (ACM), 2024
Keywords
knowledge integration, language models, prompt construction, relation extraction
National Category
Natural Language Processing
Identifiers
urn:nbn:se:kth:diva-350722 (URN)10.1145/3605098.3635949 (DOI)001236958200108 ()2-s2.0-85197687891 (Scopus ID)
Conference
39th Annual ACM Symposium on Applied Computing, SAC 2024, Avila, Spain, Apr 8 2024 - Apr 12 2024
Note

Part of ISBN 9798400702433

QC 20240719

Available from: 2024-07-17 Created: 2024-07-17 Last updated: 2025-02-07Bibliographically approved
Wessén, J., Carlsson, M., Schulte, C., Flener, P., Pecora, F. & Matskin, M. (2023). A constraint programming model for the scheduling and workspace layout design of a dual-arm multi-tool assembly robot. Constraints, 28(2), 71-104
Open this publication in new window or tab >>A constraint programming model for the scheduling and workspace layout design of a dual-arm multi-tool assembly robot
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2023 (English)In: Constraints, ISSN 1383-7133, E-ISSN 1572-9354, Vol. 28, no 2, p. 71-104Article in journal (Refereed) Published
Abstract [en]

The generation of a robot program can be seen as a collection of sub-problems, where many combinations of some of these sub-problems are well studied. The performance of a robot program is strongly conditioned by the location of the tasks. However, the scope of previous methods does not include workspace layout design, likely missing high-quality solutions. In industrial applications, designing robot workspace layout is part of the commissioning. We broaden the scope and show how to model a dual-arm multi-tool robot assembly problem. Our model includes more robot programming sub-problems than previous methods, as well as workspace layout design. We propose a constraint programming formulation in MiniZinc that includes elements from scheduling and routing, extended with variable task locations. We evaluate the model on realistic assembly problems and workspaces, utilizing the dual-arm YuMi robot from ABB Ltd. We also evaluate redundant constraints and various formulations for avoiding arm-to-arm collisions. The best model variant quickly finds high-quality solutions for all problem instances. This demonstrates the potential of our approach as a valuable tool for a robot programmer.

Place, publisher, year, edition, pages
Springer Nature, 2023
Keywords
Assembly manufacturing, Constraint programming, Robot planning and scheduling, Workspace layout design
National Category
Robotics and automation Computer Sciences
Identifiers
urn:nbn:se:kth:diva-338539 (URN)10.1007/s10601-023-09345-4 (DOI)001032500800001 ()2-s2.0-85164960102 (Scopus ID)
Note

QC 20250509

Available from: 2023-11-14 Created: 2023-11-14 Last updated: 2025-05-09Bibliographically approved
Nikolov, N., Solberg, A., Prodan, R., Soylu, A., Matskin, M. & Roman, D. (2023). Container-Based Data Pipelines on the Computing Continuum for Remote Patient Monitoring. Computer, 56(10), 40-48
Open this publication in new window or tab >>Container-Based Data Pipelines on the Computing Continuum for Remote Patient Monitoring
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2023 (English)In: Computer, ISSN 0018-9162, E-ISSN 1558-0814, Vol. 56, no 10, p. 40-48Article in journal (Refereed) Published
Abstract [en]

The emerging concept of big data pipelines provides relevant solutions and is one of the main enablers of telemedicine. We present a data pipeline for remote patient monitoring and show a real-world example of how data pipelines help address the stringent requirements of telemedicine.

Place, publisher, year, edition, pages
Institute of Electrical and Electronics Engineers (IEEE), 2023
Keywords
Patient monitoring, Telemedicine, Pipelines, Big Data
National Category
Other Computer and Information Science
Identifiers
urn:nbn:se:kth:diva-338966 (URN)10.1109/MC.2023.3285414 (DOI)001077539800007 ()2-s2.0-85174332029 (Scopus ID)
Note

QC 20231101

Available from: 2023-11-01 Created: 2023-11-01 Last updated: 2023-11-01Bibliographically approved
Layegh, A., Payberah, A. H., Soylu, A., Roman, D. & Matskin, M. (2023). ContrastNER: Contrastive-based Prompt Tuning for Few-shot NER. In: Proceedings - 2023 IEEE 47th Annual Computers, Software, and Applications Conference, COMPSAC 2023: . Paper presented at 47th IEEE Annual Computers, Software, and Applications Conference, COMPSAC 2023, Jun 26 2023 - Jun 30 2023, Hybrid, Torino, Italy (pp. 241-249). Institute of Electrical and Electronics Engineers (IEEE)
Open this publication in new window or tab >>ContrastNER: Contrastive-based Prompt Tuning for Few-shot NER
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2023 (English)In: Proceedings - 2023 IEEE 47th Annual Computers, Software, and Applications Conference, COMPSAC 2023, Institute of Electrical and Electronics Engineers (IEEE) , 2023, p. 241-249Conference paper, Published paper (Refereed)
Abstract [en]

Prompt-based language models have produced encouraging results in numerous applications, including Named Entity Recognition (NER) tasks. NER aims to identify entities in a sentence and provide their types. However, the strong performance of most available NER approaches is heavily dependent on the design of discrete prompts and a verbalizer to map the model-predicted outputs to entity categories, which are complicated undertakings. To address these challenges, we present ContrastNER, a prompt-based NER framework that employs both discrete and continuous tokens in prompts and uses a contrastive learning approach to learn the continuous prompts and forecast entity types. The experimental results demonstrate that ContrastNER obtains competitive performance to the state-of-the-art NER methods in high-resource settings and outperforms the state-of-the-art models in low-resource circumstances without requiring extensive manual prompt engineering and verbalizer design.

Place, publisher, year, edition, pages
Institute of Electrical and Electronics Engineers (IEEE), 2023
Keywords
Contrastive learning, Language Models, Named Entity Recognition, Prompt-based learning
National Category
Natural Language Processing Robotics and automation
Identifiers
urn:nbn:se:kth:diva-336748 (URN)10.1109/COMPSAC57700.2023.00038 (DOI)001046484100028 ()2-s2.0-85168863373 (Scopus ID)
Conference
47th IEEE Annual Computers, Software, and Applications Conference, COMPSAC 2023, Jun 26 2023 - Jun 30 2023, Hybrid, Torino, Italy
Note

Part of proceedings ISBN 9798350326970

QC 20231031

Available from: 2023-09-19 Created: 2023-09-19 Last updated: 2025-02-05Bibliographically approved
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ORCID iD: ORCID iD iconorcid.org/0000-0002-4722-0823

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