This paper works in the setting of multi-granulation rough sets on two universes. We combine multi-granulation ideas with set-valued mappings and introduce a multi-granulation T-rough set model built on set-valued mappings. Four inverse approximation operators are defined: a pessimistic upper inverse operator, a pessimistic lower inverse operator, an optimistic upper inverse operator, and an optimistic lower inverse operator. Using these operators, we set up a two-universe framework for multi-granulation T-rough sets. We then spell out the basic properties of the operators, prove several theorems, and clarify how the different operators relate to each other. A few examples are included to show how the model works in practice. The model extends rough set theory on two universes and gives a new way to describe information that comes from multiple sources and multiple granular levels.
Citation: Weihua Lin. A multi-granulation T-rough set model and its properties[J]. AIMS Mathematics, 2026, 11(6): 16174-16198. doi: 10.3934/math.2026665
This paper works in the setting of multi-granulation rough sets on two universes. We combine multi-granulation ideas with set-valued mappings and introduce a multi-granulation T-rough set model built on set-valued mappings. Four inverse approximation operators are defined: a pessimistic upper inverse operator, a pessimistic lower inverse operator, an optimistic upper inverse operator, and an optimistic lower inverse operator. Using these operators, we set up a two-universe framework for multi-granulation T-rough sets. We then spell out the basic properties of the operators, prove several theorems, and clarify how the different operators relate to each other. A few examples are included to show how the model works in practice. The model extends rough set theory on two universes and gives a new way to describe information that comes from multiple sources and multiple granular levels.
| [1] |
Z. Pawlak, Rough sets, International Journal of Computer and Information Sciences, 11 (1982), 341–356. https://doi.org/10.1007/BF01001956 doi: 10.1007/BF01001956
|
| [2] |
Y. H. Qian, J. Y. Liang, Y. Y. Yao, C. Y. Dang, MGRS: A multi-granulation rough set, Inform. Sciences, 180 (2010), 949–970. https://doi.org/10.1016/j.ins.2009.11.023 doi: 10.1016/j.ins.2009.11.023
|
| [3] |
A. M. Khan, A. Talukdar, Reasoning about attribute-relative approximations in multi-source environments: a modal framework with axiomatization, J. Logic. Comput., 36 (2026), exaf057. https://doi.org/10.1093/logcom/exaf057 doi: 10.1093/logcom/exaf057
|
| [4] |
D. Dubois, H. Prade, Rough fuzzy sets and fuzzy rough sets, Int. J. Gen. Syst., 17 (1990), 191–209. https://doi.org/10.1080/03081079008935107 doi: 10.1080/03081079008935107
|
| [5] |
B. Davvaz, A short note on algebraic T-rough sets, Inform. Sciences, 178 (2008), 3247–3252. https://doi.org/10.1016/j.ins.2008.03.014 doi: 10.1016/j.ins.2008.03.014
|
| [6] |
S. B. Hosseini, N. Jafarzadeh, A. Gholami, T-rough ideal and T-rough fuzzy ideal in a semigroup, Advanced Materials Research, 433-440 (2012), 4915–4919. https://doi.org/10.4028/www.scientific.net/AMR.433-440.4915 doi: 10.4028/www.scientific.net/AMR.433-440.4915
|
| [7] | S. B. Hosseini, E. Hosseinpour, T-roughness in semi-lattices, Int. J. Appl. Math. Stat., 30 (2012), 16–26. |
| [8] |
N. Yaqoob, S. Haq, Generalized rough Γ-hyperideals in Γ-semihypergroups, J. Appl. Math., 2014 (2014), 658252. https://doi.org/10.1155/2014/658252 doi: 10.1155/2014/658252
|
| [9] |
M. A. Ansari, N. Yaqoob, T-rough ideals in ternary semigroups, International Journal of Pure and Applied Mathematics, 86 (2013), 411–424. http://doi.org/10.12732/ijpam.v86i2.15 doi: 10.12732/ijpam.v86i2.15
|
| [10] |
K. M. Alsager, S. M. El-Deeb, Rough and T-rough sets arising from intuitionistic fuzzy ideals in BCK-algebras, Mathematics, 12 (2024), 2925. https://doi.org/10.3390/math12182925 doi: 10.3390/math12182925
|
| [11] |
O. Kazancı, S. Yamak, B. Davvaz, The lower and upper approximations in a quotient hypermodule with respect to fuzzy sets, Inform. Sciences, 178 (2008), 2349–2359. https://doi.org/10.1016/j.ins.2008.01.006 doi: 10.1016/j.ins.2008.01.006
|
| [12] |
E. Hosseinpour, T-rough fuzzy subgroups of groups, J. Math. Comput. Sci., 12 (2014), 186–195. http://doi.org/10.22436/jmcs.012.03.02 doi: 10.22436/jmcs.012.03.02
|
| [13] |
X. H. Zhang, Y. N. Zhang, Z. N. Xue, Y. C. Ma, T-rough approximation pairs and covering based rough sets, Fund. Inform., 142 (2015), 195–212. https://doi.org/10.3233/FI-2015-1291 doi: 10.3233/FI-2015-1291
|
| [14] |
S. Khodaii, A. A. Estaji, S. M. Anvariyeh, On category of T-rough sets, Filomat, 36 (2022), 1873–1893. https://doi.org/10.2298/FIL2206873K doi: 10.2298/FIL2206873K
|
| [15] |
C. Gallardo, G. Pelaitay, C. S. Gallardo, T-rough symmetric Heyting algebras with tense operators, Fuzzy Set. Syst., 466 (2023), 108455. https://doi.org/10.1016/j.fss.2022.12.011 doi: 10.1016/j.fss.2022.12.011
|
| [16] |
H. Garg, M. Atef, Cq-ROFRS: covering q-rung orthopair fuzzy rough sets and its application to multi-attribute decision-making process, Complex Intell. Syst., 8 (2022), 2349–2370. https://doi.org/10.1007/s40747-021-00622-4 doi: 10.1007/s40747-021-00622-4
|
| [17] |
J. H. Li, R. Zhang, H. L. Zhi, W. Sun, A review of knowledge space theory, Pattern Recognit. Artif. Intell., 37 (2024), 106–127. https://doi.org/10.16451/j.cnki.issn1003-6059.202402002 doi: 10.16451/j.cnki.issn1003-6059.202402002
|
| [18] |
J. J. Li, W. Sun, Knowledge space, formal context and knowledge base, J. Northwest Univ. (Nat. Sci. Ed.), 49 (2019), 517–526. https://doi.org/10.16152/j.cnki.xdxbzr.2019-04-004 doi: 10.16152/j.cnki.xdxbzr.2019-04-004
|
| [19] |
T. L. Yang, J. J. Li, Z. W. Li, M. Jin, Y. F. Zhou, Y. D. Lin, Two variable-precision models for constructing knowledge structures based on skills and reduction of skill subsets, Pattern Recognit. Artif. Intell., 35 (2022), 671–687. https://doi.org/10.16451/j.cnki.issn1003-6059.2022080001 doi: 10.16451/j.cnki.issn1003-6059.2022080001
|
| [20] |
Y. F. Zhou, J. J. Li, D. L. Feng, T. L. Yang, Learning paths and skill assessment in formal contexts, Pattern Recognit. Artif. Intell., 34 (2021), 1069–1084. https://doi.org/10.16451/j.cnki.issn1003-6059.202112001 doi: 10.16451/j.cnki.issn1003-6059.202112001
|
| [21] |
Y. F. Zhou, J. J. Li, H. K. Wang, W. Sun, Skills and fuzzy knowledge structures, Applications in Engineering and Technology, 42 (2022), 2629–2645. https://doi.org/10.3233/JIFS-212018 doi: 10.3233/JIFS-212018
|
| [22] | T. L. Yang, Two variable-precision models for constructing knowledge structures, Master Thesis, Minnan Normal University, 2023. |
| [23] | M. J. Zhou, Methods for constructing knowledge structures and finding learning paths under the FT-rough set model, Master Thesis, Minnan Normal University, 2025. |
| [24] |
J. P. Doignon, J. C. Falmagne, Spaces for the assessment of knowledge, International Journal of Man-Machine Studies, 23 (1985), 175–196. https://doi.org/10.1016/S0020-7373(85)80031-6 doi: 10.1016/S0020-7373(85)80031-6
|
| [25] | S. B. Hosseini, N. Jafarzadeh, A. Gholami, T-rough (prime, primary) ideal and T-rough fuzzy (prime, primary) ideal on commutative rings, Int. J. Contemp. Math. Sci., 7 (2012), 337–350. |
| [26] |
C. Y. Huang, H. L. Huang, J. J. Yang, Q. J. Wang, J. J. Li, Knowledge structures constructed by variable precision model, J. Shanxi Univ. (Nat. Sci. Ed.), 48 (2025), 43–54. https://doi.org/10.13451/j.sxu.ns.2024135 doi: 10.13451/j.sxu.ns.2024135
|
| [27] |
J. P. Zhang, W. Z. Wu, M. J. Zhou, J. J. Li, Distributed serial fuzzy relations and the meshing of fuzzy knowledge structures, J. Shandong Univ. (Nat. Sci. Ed.), 60 (2025), 116–124. https://doi.org/10.6040/j.issn.1671-9352.0.2024.291 doi: 10.6040/j.issn.1671-9352.0.2024.291
|
| [28] | H. L. Yang, Rough set theory and methods on two universes, Beijing: Science Press, 2016. |
| [29] |
D. L. Wang, Q. Y. Xu, J. J. Li, Y. F. Zhu, Knowledge assessment and learning path selection under knowledge point network, J. Nanjing Univ. (Nat. Sci. Ed.), 59 (2023), 629–643. https://doi.org/10.13232/j.cnki.jnju.2023.04.010 doi: 10.13232/j.cnki.jnju.2023.04.010
|
| [30] |
J. Heller, C. Repitsch, Distributed skill functions and the meshing of knowledge, J. Math. Psychol., 52 (2008), 147–157. https://doi.org/10.1016/j.jmp.2008.01.003 doi: 10.1016/j.jmp.2008.01.003
|
| [31] |
L. Stefanutti, On the assessment of procedural knowledge: from problem spaces to knowledge spaces, Brit. J. Math. Stat. Psy., 72 (2019), 185–218. https://doi.org/10.1111/bmsp.12139 doi: 10.1111/bmsp.12139
|
| [32] |
S. Kousar, N. Kausar, Multi-criteria decision making for sustainable agritourism: an integrated fuzzy-rough approach, Spectrum of Operational Research, 2 (2025), 175–191. https://doi.org/10.31181/sor21202515 doi: 10.31181/sor21202515
|
| [33] |
J. C. Jiang, X. D. Liu, Z. W. Wang, W. P. Ding, S. T. Zhang, H. Xu, Large group decision making with a rough integrated asymmetric cloud model under multi granularity linguistic environment, Inform. Sciences, 678 (2024), 120994. https://doi.org/10.1016/j.ins.2024.120994 doi: 10.1016/j.ins.2024.120994
|
| [34] |
R. Gul, An extension of VIKOR approach for MCDM using bipolar fuzzy preference δ-covering based bipolar fuzzy rough set model, Spectrum of Operational Research, 2 (2025), 72–91. https://doi.org/10.31181/sor21202511 doi: 10.31181/sor21202511
|
| [35] |
T. Fujita, The hyperfuzzy VIKOR and hyperfuzzy DEMATEL methods for multi-criteria decision-making, Spectrum of Decision Making Applications, 3 (2026), 292–315. https://doi.org/10.31181/sdmap31202654 doi: 10.31181/sdmap31202654
|
| [36] |
T. Fujita, Shadowed offset: integrating offset and shadowed set frameworks for enhanced uncertainty modeling, Spectrum of Operational Research, 2025 (2025), 1–17. https://doi.org/10.31181/sor4152 doi: 10.31181/sor4152
|
| [37] | Y. P. Liu, Research on the method of selecting items for cognitive diagnosis adaptive testing based on knowledge space theory, Master Thesis, Bohai University, 2019. |