@article{Xu2023, 
author = {Jiaqi Xu and Chunyan Xue},
title = {Uniqueness and existence of positive periodic solutions of functional differential equations},
year = {2023},
journal = {AIMS Mathematics},
volume = {8},
number = {1},
pages = {676-690},
keywords = {functional differential equation, positive periodic solution, uniqueness and existence, Hilbert's metric, fixed point theorem},
url = {https://www.sciopen.com/article/10.3934/math.2023032},
doi = {10.3934/math.2023032},
abstract = {In this paper, some new findings on the uniqueness and existence of positive periodic solutions to first-order functional differential equations are presented. These equations have wide applications in a variety of fields. The most important feature of our argument is that we use the theory of Hilbert's metric to prove the uniqueness of the positive periodic solution when    q  =  −  1 and    −  1  <  q  <  0. In addition, we also investigate the existence results of positive periodic solutions by applying a fixed point theorem for completely continuous maps in a cone. Two examples demonstrate our findings.}
}