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Now showing items 1-10 of 23

#### Constant-sign periodic and almost periodic solutions of a system of difference equations

(Elsevier BV, 2005-11-01)

#### On constant-sign periodic solutions in modelling the spread of interdependent epidemics

(Cambridge University Press (CUP), 2006-01-01)

We consider the following model that describes the spread of n types of epidemics which are interdependent on each other:
u(i)(t) = integral(t)(t-r) g(i)(t, s) f(i) (s, u(1)(s), u(2)(s),..., u(n)(s))ds, t is an element of ...

#### Construction of upper and lower solutions for singular discrete initial and boundary value problems via inequality theory

(Springer Nature, 2005-01-01)

We present new existence results for singular discrete initial and boundary value problems. In particular our nonlinearity may be singular in its dependent variable and is allowed to change sign.

#### Solvability of singular second order m-point boundary value problems

(Elsevier BV, 2005-01-01)

#### Twin positive periodic solutions of second order singular differential systems

(Uniwersytet Mikolaja Kopernika/Nicolaus Copernicus University, 2005-06-01)

In this paper, we study positive periodic solutions to singular second order differential systems. It is proved that such a problem has at least two positive periodic solutions. The proof relies on a nonlinear alternative ...

#### Multiplicity of positive periodic solutions to second order differential equations

(Cambridge University Press (CUP), 2006-04-01)

In this paper, we study the existence of positive periodic solutions to the equation x" = f (t, x). It is proved that such a equation has more than one positive periodic solution when the nonlinearity changes sign. ...

#### Singular positone and semipositone boundary value problems of second order delay differential equations

(Institute of Mathematics, Czech Academy of Sciences, 2005-06-01)

In this paper we present some new existence results for singular positone and semipositone boundary value problems of second order delay differential equations. Throughout our nonlinearity may be singular in its dependent ...

#### A note on equilibria for abstract economies

(Elsevier BV, 2001-08-01)