aspg-21-3704-1791465327 20261008131527 American Scientific Publishing Group admin@americaspg.com American Scientific Publishing Group International Journal of Neutrosophic Science IJNS 2692-6148 2690-6805 2025 26 2 Sarra Boudaoud Laboratory of Pure and Applied Mathematics, Faculty of Mathematics and Computer Science, University of M’sila, University Pole, Raod Bordj Bou Arreridj, M’sila 28000, Algeria Lemnaouar Zedam Laboratory of Pure and Applied Mathematics, Faculty of Mathematics and Computer Science, University of M’sila, University Pole, Raod Bordj Bou Arreridj, M’sila 28000, Algeria Soheyb Milles Laboratory of Science for Mathematics, Computer Science and Engineering Applications, Department of Mathematics, University Center of Barika, Amdoukal Road, Barika, 05001, Algeria In this paper, we study the notion of principal (crisp) fuzzy ideals (resp. filters) on the setting of trellises (or weakly associative lattices as called by several authors). More specifically, we introduce the notions of L-fuzzy ideals and L-fuzzy filters on a given trellis and provide basic characterizations of these notions based on their weakly associative meet and join operations. We pay particular attention to the kind of principal L-fuzzy ideals (resp. filters) on a given trellis, which are more complicated in the absence of the (associativity) transitivity property. 2025 164 181 3704 https://creativecommons.org/licenses/by/4.0/ 10.54216/IJNS.260212 https://www.americaspg.com/journal/21/article/3704 https://www.americaspg.com/storage/71741962395.pdf