Circuits and Efficiency in Incomplete Block Designs
本文解释了设计品种共现图中的回路数量为何能作为其效率的衡量指标，并提出一个猜想：寻找最优调和平均效率因子的设计可限于短回路数量最少的设计，这能大幅节省高效设计的构造工作。
This paper explains why numbers of circuits in the variety concurrence graph of a design provide an attractive measure of its efficiency. It is conjectured that the search for designs with an optimal value of the harmonic mean efficiency factor can be restricted to those with minimal numbers of circuits of shorter lengths. This conjecture is seen to be highly plausible, to be a natural generalization of a conjecture that is already widely accepted and to offer significant savings in the construction of efficient designs.