Generalized monogamy inequalities of convex-roof extended negativity in   $N$-qubit systems
  In this paper, we present some generalized monogamy inequalities based on negativity and convex-roof extended negativity (CREN). These monogamy relations are satisfied by the negativity of $N$-qubit quantum systems $ABC_1\cdots C_{N-2}$, under the partitions $AB|C_1\cdots C_{N-2}$ and $ABC_1|C_2\cdots C_{N-2}$. Furthermore, the $W$-class states are used to test these generalized monogamy inequalities. 
Yanmin Yang, Wei Chen, Gang Li and Zhu-Jun Zheng
quant-ph