On the algebraic structures in $\A_Φ(G)$

Abstract: Let $G$ be a locally compact group and $(\Phi, \Psi)$ be a complementary pair of $N$-functions. In this paper, using the powerful tool of porosity, it is proved that when $G$ is an amenable group, then the Fig`a-Talamanca-Herz-Orlicz algebra ${\A}{\Phi}(G)$ is a Banach algebra under convolution product if and only if $G$ is compact. Then it is shown that ${\A}{\Phi}(G)$ is a Segal algebra, and as a consequence, the amenability of ${\A}{\Phi}(G)$ and the existence of a bounded approximate identity for ${\A}{\Phi}(G)$ under the convolution product is discussed. Furthermore, it is shown that for a compact abelian group $G$, the character space of ${\A}_{\Phi}(G)$ under convolution product can be identified with $\widehat{G}$, the dual of $G$.