We establish a fixed-point theorem for mappings of square matrices of all sizes which respect the matrix sizes and direct sums of matrices. The conclusions are stronger if such a mapping is a free noncommutative function, i.e., if it respects matrix similarities. As a special case, we obtain the corresponding version of the Banach Contraction Mapping Theorem. This result is then applied to prove the existence and uniqueness of a solution of the initial value problem for ODEs in noncommutative spaces. As a by-product of the ideas developed in this paper, we establish a noncommutative version of the principle of nested closed sets. We prove the implicit function theorem and the inverse function theorem in two different settings: for free noncommutative functions over operator spaces and for free noncommutative functions on the set of nilpotent matrices.
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Title
Fixed-point and implicit/inverse function theorems for free noncommutative functions
Creators
Gulnara K. Abduvalieva - DU
Contributors
Dmitry S. Kaliuzhnyi-Verbovetskyi (Advisor) - Drexel University (1970-)
Awarding Institution
Drexel University
Degree Awarded
Doctor of Philosophy (Ph.D.)
Publisher
Drexel University; Philadelphia, Pennsylvania
Resource Type
Dissertation
Language
English
Academic Unit
College of Arts and Sciences; Drexel University; Mathematics
Other Identifier
6318; 991014632561104721
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