### Three methods for the study of semilinear equations at resonance

Bogdan Przeradzki (1993)

Colloquium Mathematicae

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Three methods for the study of the solvability of semilinear equations with noninvertible linear parts are compared: the alternative method, the continuation method of Mawhin and a new perturbation method [22]-[27]. Some extension of the last method and applications to differential equations in Banach spaces are presented.