Concatenating Ordered Set

Definition

• With ${\beta }_1=\{{\alpha }_1,\dots ,{\alpha }_n\}$
• With ${\beta }_2=\{x_1,\dots ,x_k\}$
• $\{{\beta }_1,{\beta }_2\}=\{{\alpha }_1,\dots ,{\alpha }_n,x_1,\dots ,x_k\}$