Published online by Cambridge University Press: 20 November 2018
We give necessary and sufficient conditions of the ${{L}^{p}}$-well-posedness (resp. $B_{p,\,q}^{s}$-wellposedness) for the second order degenerate differential equation with finite delays
with periodic boundary conditions $\left( Mu \right)\,\left( 0 \right)\,=\,\left( Mu \right)\,\left( 2\pi \right),\,{{\left( Mu \right)}^{\prime }}\left( 0 \right)\,=\,{{\left( Mu \right)}^{\prime }}\left( 2\pi \right)$, where $A,\,B,\,\text{and}\,M$ are closed linear operators on a complex Banach space $X$ satisfying $D\left( A \right)\,\cap \,D\left( B \right)\,\subset \,D\left( M \right)$, $F\,\text{and}\,G$ are bounded linear operators from ${{L}^{p}}\left( \left[ -2\pi ,\,0 \right];\,X \right)\,\left( \text{resp}\text{.}\,\text{B}_{p,q}^{s}\left( \left[ -2\pi ,\,0 \right];\,X \right) \right)$ into $X$.