Representations and module-extensions of hom 3-Lie algebras

In this paper, we study the representations and module-extensions of hom 3-Lie algebras. We show that a linear map between hom 3-Lie algebras is a morphism if and only if its graph is a hom 3-Lie subalgebra and show that the derivations of a hom 3-Lie algebra is a Lie algebra. Derivation extension of hom 3-Lie algebras are also studied as an application. Moreover, we introduce the definition of $T_{\theta }$-extensions and $T_{\theta }^{\ast }$-extensions of hom 3-Lie sub-algebras in terms of modules, provide the necessary and sufficient conditions for $2k$-dimensional metric hom 3-Lie algebra to be isomorphic to a $T_{\theta }^{\ast }$-extensions.