The existence of multiple positive periodic solutions for functional differential equations

The existence of multiple positive solutions for the integral equation x(t)=∫tt+ωG(t,s)b(s)f(s,x(s-τ1(s)),…,x(s-τn(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.