Periodic Solutions of Periodic Retarded Functional Differential Equations
Marcin Pawłowski (2004)
Bulletin of the Polish Academy of Sciences. Mathematics
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The paper presents a geometric method of finding periodic solutions of retarded functional differential equations (RFDE) , where f is T-periodic in t. We construct a pair of subsets of ℝ × ℝⁿ called a T-periodic block and compute its Lefschetz number. If it is nonzero, then there exists a T-periodic solution.