Songkiat Sumetkijakan

Songkiat Sumetkijakan

Ajarn Weng (อาจารย์เว้ง)

Publications

You can also find my articles on my Google Scholar profile.

Journal Articles

Joining Copulas of Extreme Implicit Dependence Copulas

Published in International Journal of Approximate Reasoning, 2025

We characterize extreme implicit dependence copulas in terms of the extremality of the joining copulas in the class of subcopulas on a domain involving the invertible copulas.

Recommended citation: N. Yanpaisan, T. Santiwipanont, S. Sumetkijakan (2025). "Joining copulas of extreme implicit dependence copulas." International Journal of Approximate Reasoning. 186, 109518.
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Extremality of Factorizable Copulas and Implicit Dependence Copulas

Published in Journal of Mathematical Analysis and Applications, 2024

We obtain characterizations of extreme factorizable copulas and prove that implicit dependence copulas whose joining copula is one of the Fréchet-Hoeffding bounds are extreme. This condition, however, is not necessary, which will be shown via some examples of extreme implicit dependence copulas.

Recommended citation: T. Santiwipanont, S. Sumetkijakan, N. Yanpaisan, Extremality of factorizable copulas and implicit dependence copulas, Journal of Mathematical Analysis and Applications, Volume 543, Issue 1, 2025, 128863.
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Characterization of Idempotent Copulas

Published in Dependence Modeling, 2023

We obtain an explicit characterization of pre-idempotent copulas, which is split into cases according to the atomicity of its associated \(\sigma\)-algebras, where the nonatomic case gives all factorizable copulas and the totally atomic case yields conjugates of ordinal sums of copies of the product copula.

Recommended citation: W. Chamnan, S. Sumetkijakan, Characterization of Pre-idempotent Copulas, Dependence Modeling, vol. 11, no. 1, 2023, pp. 20230106.
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Countably Piecewise Monotonic Surjection Implicit Dependence Copulas

Published in Fuzzy Sets and Systems, 2022

We obtain a characterization of implicit dependence copulas in terms of generalized Markov products of CPMS left and right invertible copulas.

Recommended citation: P. Panyasakulwong, T. Santiwipanont, S. Sumetkijakan, N. Yanpaisan, Countably piecewise monotonic surjection implicit dependence copulas, Fuzzy Sets and Systems, Volume 448, 2022, Pages 49-64.
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Conference Papers

Paper Title Number 4

Published in GitHub Journal of Bugs, 2024

This paper is about fixing template issue #693.

Recommended citation: Your Name, You. (2024). "Paper Title Number 3." GitHub Journal of Bugs. 1(3).
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