The minimal vertex - covering problem of graph is a NP-complete problem of graph theory.
图的最小顶点覆盖问题是图论中的一个NP完全问题。
The crossing number of graph, which is an NP-complete problem, has an important theory meaning.
图的交叉数问题属于NP -困难问题，对它的研究有重要的理论意义。
The vessel stowage planning is not only a complex combination and optimization problem, but also a NP-Complete problem.
大型集装箱船舶配载问题是一个复杂的组合优化问题，而且是一个NP问题。
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