Tighter generalized monogamy and polygamy relations for multiqubit systems

We present a different kind of monogamy and polygamy relations based on concurrence and concurrence of assistance for multiqubit systems. By relabeling the subsystems associated with different weights, a smaller upper bound of the $\alpha$th ($0\le \alpha \le 2$) power of concurrence for multiqubit states is obtained. We also present tighter monogamy relations satisfied by the $\alpha$th ($0\le \alpha \le 2$) power of concurrence for $N$-qubit pure states under the partition $AB$ and $C_1\mathrm{.}\mathrm{.}\mathrm{.}{C}_{N-2}$, as well as under the partition $AB{C}_1$ and $C_2\cdots C_{N-2}$. These inequalities give rise to the restrictions on entanglement distribution and the trade off of entanglement among the subsystems. Similar results are also derived for negativity.