  Bollob\'{a}s and Scott [5] conjectured that every graph $G$ has a balanced
bipartite spanning subgraph $H$ such that for each $v\in V(G)$, $d_H(v)\ge
(d_G(v)-1)/2$. In this paper, we show that every graphic sequence has a
realization for which this Bollob\'{a}s-Scott conjecture holds, confirming a
conjecture of Hartke and Seacrest [10]. On the other hand, we give an infinite
family of counterexamples to this Bollob\'{a}s-Scott conjecture, which
indicates that $\lfloor (d_G(v)-1)/2\rfloor$ (rather than $(d_G(v)-1)/2$) is
probably the correct lower bound. We also study bipartitions $V_1, V_2$ of
graphs with a fixed number of edges. We provide a (best possible) upper bound
on $e(V_1)^{\lambda}+e(V_2)^{\lambda}$ for any real $\lambda\geq 1$ (the case
$\lambda=2$ is a question of Scott [13]) and answer a question of Scott [13] on
$\max\{e(V_1),e(V_2)\}$.
