Document Type : Research Paper


Department of Mathematics, Ardabil Branch, Islamic Azad University, Ardabil, Iran.


Let $\mathcal{X}$ be a partially ordered set and $d$ be a generalized metric on $\mathcal{X}$. We obtain some results in coupled and coupled coincidence of $g$-monotone functions on $\mathcal{X}$, where $g$ is a function from $\mathcal{X}$ into itself. Moreover, we show that a nonexpansive mapping on a partially ordered Hilbert space has a fixed point lying in  the unit ball of  the Hilbert space. Some applications for linear and nonlinear matrix equations are given.


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