In these separate notes, we give an exposition on Fredholm operators between Banach spaces. In particular, we prove the theorems stated in the last section of the first lecture .

In this paper, we show that an unbounded weakly S0-demicompact linear operator T, introduced in [18], acting on a Banach space, can be characterized by some measures of weak noncompactness. Moreover, our results are illustrated to discuss the relationship with Fredholm and upper semi-Fredholm operators as well stability essential spectrum T.

Operators of Wiener-Hopf plus Hankel type have been receiving an increasing attention in the last years (see [1, 2, 4, 6, 10, 12–16]). Some of the interest in their study arises directly from concrete applications where these kind of operators appear. This is the case in problems of wave diffraction by some particular rectangular geometries which originate specific boundary-transmission value p...