Bi-Fuzzy S-Approximation Spaces

The S-approximation spaces are significant extension of the rough set model and have been widely applied in intelligent decision-making. However, traditional S-approximation spaces are limited to two crisp universes, whereas bi-fuzzy universes (i.e., two distinct fuzzy domains) are more prevalent in...

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Main Authors: Ronghai Wang, Xiaojie Xie, Huilai Zhi
Format: Article
Language:English
Published: MDPI AG 2025-01-01
Series:Mathematics
Subjects:
Online Access:https://www.mdpi.com/2227-7390/13/2/324
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author Ronghai Wang
Xiaojie Xie
Huilai Zhi
author_facet Ronghai Wang
Xiaojie Xie
Huilai Zhi
author_sort Ronghai Wang
collection DOAJ
description The S-approximation spaces are significant extension of the rough set model and have been widely applied in intelligent decision-making. However, traditional S-approximation spaces are limited to two crisp universes, whereas bi-fuzzy universes (i.e., two distinct fuzzy domains) are more prevalent in practical applications. To bridge this gap, this study introduces the bi-fuzzy S-approximation spaces (BFS approximation spaces) as an advancement of knowledge space theory’s fuzzy extension. Upper and lower approximation operators are formally defined, and the properties of BFS approximation spaces under various operations, such as complement, intersection and union are systematically explored. Special attention is given to a significant form of these operators, under which the monotonicity and complementary compatibility of BFS approximation spaces are rigorously analyzed. These results not only extend the theoretical framework of S-approximation spaces but also pave the way for further exploration of fuzzy extensions within knowledge space theory.
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spelling doaj-art-aea7e283f3e447f3b4947bfaf24f0fe12025-01-24T13:40:11ZengMDPI AGMathematics2227-73902025-01-0113232410.3390/math13020324Bi-Fuzzy S-Approximation SpacesRonghai Wang0Xiaojie Xie1Huilai Zhi2School of Mathematics and Computer Science, Quanzhou Normal University, Quanzhou 362000, ChinaSchool of Mathematics and Statistics, Minnan Normal University, Zhangzhou 363000, ChinaSchool of Mathematics and Computer Science, Quanzhou Normal University, Quanzhou 362000, ChinaThe S-approximation spaces are significant extension of the rough set model and have been widely applied in intelligent decision-making. However, traditional S-approximation spaces are limited to two crisp universes, whereas bi-fuzzy universes (i.e., two distinct fuzzy domains) are more prevalent in practical applications. To bridge this gap, this study introduces the bi-fuzzy S-approximation spaces (BFS approximation spaces) as an advancement of knowledge space theory’s fuzzy extension. Upper and lower approximation operators are formally defined, and the properties of BFS approximation spaces under various operations, such as complement, intersection and union are systematically explored. Special attention is given to a significant form of these operators, under which the monotonicity and complementary compatibility of BFS approximation spaces are rigorously analyzed. These results not only extend the theoretical framework of S-approximation spaces but also pave the way for further exploration of fuzzy extensions within knowledge space theory.https://www.mdpi.com/2227-7390/13/2/324S-approximation spacesrough setsfuzzy setsbi-fuzzy S-approximation spaces (BFS approximation spaces)monotonicitycomplementary compatibility
spellingShingle Ronghai Wang
Xiaojie Xie
Huilai Zhi
Bi-Fuzzy S-Approximation Spaces
Mathematics
S-approximation spaces
rough sets
fuzzy sets
bi-fuzzy S-approximation spaces (BFS approximation spaces)
monotonicity
complementary compatibility
title Bi-Fuzzy S-Approximation Spaces
title_full Bi-Fuzzy S-Approximation Spaces
title_fullStr Bi-Fuzzy S-Approximation Spaces
title_full_unstemmed Bi-Fuzzy S-Approximation Spaces
title_short Bi-Fuzzy S-Approximation Spaces
title_sort bi fuzzy s approximation spaces
topic S-approximation spaces
rough sets
fuzzy sets
bi-fuzzy S-approximation spaces (BFS approximation spaces)
monotonicity
complementary compatibility
url https://www.mdpi.com/2227-7390/13/2/324
work_keys_str_mv AT ronghaiwang bifuzzysapproximationspaces
AT xiaojiexie bifuzzysapproximationspaces
AT huilaizhi bifuzzysapproximationspaces