Robustness against design breakdown following observation loss is investigated for Partially Balanced Incomplete Block Designs with two associate classes (PBIBD(2)s). New results are obtained which add to the body of knowledge on PBIBD(2)s. In particular, using an approach based on the E-value of a design, all PBIBD(2)s with triangular and Latin square association schemes are established as having optimal block breakdown number. Furthermore, for group divisible designs not covered by existing results in the literature, a sufficient condition for optimal block breakdown number establishes that all members of some design sub-classes have this property.

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关于 PBIBD(2)s 在观测丢失的情况下对击穿的稳健性的说明

对于具有两个关联类 (PBIBD(2)s) 的部分平衡不完整块设计，研究了针对观察损失后设计故障的稳健性。获得了新的结​​果，这些结果增加了关于 PBIBD(2)s 的知识体系。特别是，使用基于设计的 E 值的方法，所有具有三角形和拉丁方关联方案的 PBIBD(2) 都被建立为具有最佳块故障数。此外，对于文献中现有结果未涵盖的群可分设计，最佳块分解数的充分条件确定某些设计子类的所有成员都具有此属性。