# H. Boua

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Articles: 2

### Equality between different types of invertibility

Methods Funct. Anal. Topology 27 (2021), no. 1, 31-36

Necessary and sufficient conditions for the between different types of invertibility are established.

Встановлені необхідні та достатні умови співпадіння різних типів оборотності.

### Upper semi-Fredholm and Kato spectrum of an $\alpha$-times integrated semigroup

Hamid Boua

Methods Funct. Anal. Topology 26 (2020), no. 1, 63-67

Let $(T(t))_{t\geq 0}$ be an $\alpha$-times integrated semigroup with generator $A$ on a Banach space $X$. In this paper, we show that the spectral mapping theorem holds for upper semi-Fredholm spectrum and we will give some consequences of this result. We also give an application on the Schrödinger operator.