Functional analysis

This thesis discusses propagators and uses them to
construct a solution to the following initial value problem
under some special conditions: {du(t)/dt = A(t)u(t) u(s) = φ where A(t) is a linear operator in a Banach space X for
every t ε R, φ ε X, and s ε R.

Spectral theory, mathematical system theory, evolution equations, differential and difference equations [electronic resource] : 21st International Workshop on Operator Theory and Applications, Berlin, July 2010.It is known that lattice homomorphisms and G-solvable positive operators on Banach lattices have cyclic peripheral spectrum (See [17]). In my thesis I prove that positive contractions whose spectral radius is 1 on Banach lattices with increasing norm have cyclic peripheral point spectrum. I also prove that if the Banach lattice is a K B space satisfying the growth conditon and º is an eigenvalue of a positive contraction T such that [º] = 1, then 1 is also an eigenvalue of T as well as an eigenvalue of T¨, the dual of T. I also investigate the conditions on contraction operators on Hilbert lattices and AL-spaces which guanantee that 1 is an eigenvalue. As we know from [17], if T : E-E is a positive ideal irreducible operator on E such the r (T) = 1 is a pole of the resolvent R(º, T), then r (T) is simple pole with dimN (T -r(T)I) and ºper(T) is cyclic. Also all points of ºper(T) are simple poles of the resolvent R(º,T). SInce band irreducibility and º-order continuity do not imply ideal irreducibility [2], we prove the analogous results for band irreducible, º-order continuous operators.

Identifying and classifying the complemented subspaces of L p , p > 2, has provided much insight into the geometric structure of Lp . In 1981, Bourgain, Rosenthal, and Schechtman proved the existence of uncountably many isomorphically distinct complemented subspaces of L p , p > 2. In 1999, Dale Alspach introduced a systematic method of studying the complemented subspaces of Lp , p > 2. In this thesis, the theory of Lp spaces is developed with a concentration on techniques used to study the complemented subspaces. We define the Alspach norm and show that the possible complemented subspaces of Lp , p > 2, generated by two compatible partitions and weights are £2, £p, £2 EB £p, and(2.:EfJ £2)ep ' We have not discovered any previously unknown complemented subspaces of Lp , but this method has reduced the study and classification of these subspaces to a study of partitions of N.