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«THE BULLETIN OF IRKUTSK STATE UNIVERSITY». SERIES «MATHEMATICS»
«IZVESTIYA IRKUTSKOGO GOSUDARSTVENNOGO UNIVERSITETA». SERIYA «MATEMATIKA»
ISSN 1997-7670 (Print)
ISSN 2541-8785 (Online)

List of issues > Series «Mathematics». 2026. Vol 56

Fixed Points of Multi-valued Almost Pseudo-contractions in Quasimetric Spaces

Author(s)

Luong V. Nguyen

Hong Duc University, Thanh Hoa, Vietnam

Abstract
In this paper, we establish a new fixed point theorem for multi-valued almost pseudo-contractive mappings in quasimetric spaces, extending and improving several known results in the literature. Our approach generalizes earlier works by allowing the contractive constant to the whole interval [0, 1), rather than being subject to more restrictive bounds. As an application, we derive new data dependence results for the fixed point sets of such mappings in quasimetric spaces.
About the Authors
Luong V. Nguyen, Dr. (Math.), Assoc. Prof., Faculty of Natural Sciences, Hong Duc University, Thanh Hoa, 440000, Vietnam, nguyenvanluong@hdu.edu.vn
For citation
Nguyen L. V. Fixed Points of Multi-valued Almost Pseudo-contractions in Quasimetric Spaces. The Bulletin of Irkutsk State University. Series Mathematics, 2026, vol. 56, pp. 97–112. https://doi.org/10.26516/1997-7670.2026.56.97
Keywords
multi-valued mappings, almost pseudo-contractions, fixed point, data dependence, quasimetric spaces
UDC
517.98
MSC
47H10, 49J53, 54H25
DOI
https://doi.org/10.26516/1997-7670.2026.56.97
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