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New conditions for the existence of non trivial solutions to some Volterra equations.

W. Okrasinski (1990)

Extracta Mathematicae

We consider the following Volterra equation:(1)       u(x) = ∫0x k(x-s) g(u(s)) ds,   where,k: [0, δ0] → R is an increasing absolutely continuous function such thatk(0) = 0g: [0,+ ∞) → [0,+ ∞) is an increasing absolutely continuous function such that g(0) = 0 and g(u)/u → ∞ as u → 0+ (see [3]).Let us note that (1) has always the trivial solution u = 0.Some necessary and sufficient conditions for the existence of nontrivial solutions to (1) with k(x) = xα - 1 (α>0) are given in [1], [2] and...

New spectral criteria for almost periodic solutions of evolution equations

Toshiki Naito, Nguyen Van Minh, Jong Son Shin (2001)

Studia Mathematica

We present a general spectral decomposition technique for bounded solutions to inhomogeneous linear periodic evolution equations of the form ẋ = A(t)x + f(t) (*), with f having precompact range, which is then applied to find new spectral criteria for the existence of almost periodic solutions with specific spectral properties in the resonant case where e i s p ( f ) ¯ may intersect the spectrum of the monodromy operator P of (*) (here sp(f) denotes the Carleman spectrum of f). We show that if (*) has a bounded...

Non-autonomous implicit integral equations with discontinuous right-hand side

Giovanni Anello, Paolo Cubiotti (2004)

Commentationes Mathematicae Universitatis Carolinae

We deal with the implicit integral equation h ( u ( t ) ) = f ( t , I g ( t , z ) u ( z ) d z ) for a.a. t I , where I : = [ 0 , 1 ] and where f : I × [ 0 , λ ] , g : I × I [ 0 , + [ and h : ] 0 , + [ . We prove an existence theorem for solutions u L s ( I ) where the contituity of f with respect to the second variable is not assumed.

Non-autonomous vector integral equations with discontinuous right-hand side

Paolo Cubiotti (2001)

Commentationes Mathematicae Universitatis Carolinae

We deal with the integral equation u ( t ) = f ( t , I g ( t , z ) u ( z ) d z ) , with t I : = [ 0 , 1 ] , f : I × n n and g : I × I [ 0 , + [ . We prove an existence theorem for solutions u L s ( I , n ) , s ] 1 , + ] , where f is not assumed to be continuous in the second variable. Our result extends a result recently obtained for the special case where f does not depend explicitly on the first variable t I .

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