On a boundary value problem for scalar linear functional differential equations

Abstract

Theorems on the Fredholm alternative and well-posedness of the linear boundary value problem u′(t)=ℓ(u)(t)+q(t), h(u)=c, where ℓ:C([a,b];ℝ)→L([a,b];ℝ) and h:C([a,b];ℝ)→ℝ are linear bounded operators, q∈L([a,b];ℝ), and c∈ℝ, are established even in the case when ℓ is not a strongly bounded operator. The question on the dimension of the solution space of the homogeneous equation u′(t)=ℓ(u)(t) is discussed as well.