关于一个定义的解释，请求帮忙！

skysophie

Definitions.-An arrangement of v objects (called treatments) in b sets
(called blocks) will be called a pairwise balanced design of index unity and type
0 f, `$ b. |* {(v; ki, k2, .. ., ki) if each block contains either k1, k2, .. ., or km treatments which
6 Z/ f  W7 r3 F9 Z; V$ G4 oare all distinct (k, < v, k, $ kj), and every pair of distinct treatments occurs exactly
in one block of the design. If the number of blocks containing k, treatments is
  n  P' j% F) j7 S$ V% [% rb,, then clearly  b = A bi, v(v-1) = i biki(k -1)。。。
- Z* m6 v2 ^3 R3 l: R4 {& a
谁能帮我解释一下，可以举个简单的例子。。谢谢！~
0 |- [+ ]' e) V8 @2 Q

角凳

是告诉我们这是哪个领域的么？？