The existence of multiple positive periodic solutions for functional differential equations

Abstract

The existence of multiple positive solutions for the integral equation x ( t ) = ∫ t t + ω G ( t , s ) b ( s ) f ( s , x ( s - τ 1 ( s ) ) , … , x ( s - τ n ( s ) ) ) ds is studied by using fixed point index theory. Using these results we obtain new results on the existence of multiple positive periodic solutions for some first order periodic functional differential equations.