This innovative reference contains a detailed study of linear abstract degenerate differential equations and the regularity of their relations, using the semigroups generated by multivalued (linear) operators and extensions of the operational method of Da Prato and Grisvard. With over 1500 references and equations, Degenerate Differential Equations in Banach Spaces is suitable for mathematical analysts, differential geometers, topologists, pure and applied mathematicians, physicists, engineers, and graduate students in these disciplines.