My textbook defines a bipartite graph in the following way:
A graph $G = (V, E)$ is called bipartite if $V = V_1 \cup V_2$ with $V_1 \cap V_2 = \emptyset$, and every edge of $G$ is of the form $\{a, b\}$ with $a \in V_1$ and $b \in V_2$.
So from this definition, we could have $V_1 = \emptyset$ and $V_2 = H$ where $H$ is a set of vertices with no edges. In otherwards, any graph containing only vertices and not edges is considered bipartite.
Is this true?