Positive periodic solutions for a neutral Lotka–Volterra system with state dependent delays

By using a fixed point theorem of strict-set-contraction, some new criteria are established for the existence of positive periodic solutions of the following periodic neutral Lotka–Volterra system with state dependent delaysdxi(t)dt=xi(t)ri(t)-∑j=1naij(t)xj(t)+∑j=1nbij(t)xj(t-τij(t,x1(t),…,xn(t)))+∑j=1ncij(t)xj′(t-σij(t,x1(t),…,xn(t))),i=1,2,…,n,where ri,aij∈C(R,R+),bij,cij∈C(R,R)(i,j=1,2,…,n)ri,aij∈C(R,R+),bij,cij∈C(R,R)(i,j=1,2,…,n) are ω  -periodic functions and τij,σij∈C(Rn+1,R)(i,j=1,2,…,n)τij,σij∈C(Rn+1,R)(i,j=1,2,…,n) are ω-periodic functions with respect to their first arguments, respectively.