casing sub meaning in English

套管异径接头

In this thesis , we first introduce the methodology of combinatorial design of testing parameters and the effectiveness of pairwise testing . then we define pair - combinatorial graph ( pcg ) and case sub graph ( csg ) to analyze the pair - cover problem and indicate that to achieve a minimum test set for pairwise testing is an npc problem , but the size of such test set is in a predictable range
本文首先介绍基于参数组合的测试设计方法和配对覆盖测试方法的有效性，并提出配对组合图( pair - combinatorialgraph ， pcg )和案例子图( casesubgraph ， csg )的概念来描述配对覆盖问题。