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
4 P% z' I7 F3 f3 Q: R(called blocks) will be called a pairwise balanced design of index unity and type
2 x5 o: Z: {7 C! g1 |9 N( k3 j(v; ki, k2, .. ., ki) if each block contains either k1, k2, .. ., or km treatments which
are 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
, L9 U  h" t. b6 M* L6 p+ [b,, then clearly  b = A bi, v(v-1) = i biki(k -1)。。。

; Q2 `$ E% l; B& i. Q8 ]2 G谁能帮我解释一下，可以举个简单的例子。。谢谢！~
& m) a8 b: C+ P" d4 ?8 V

角凳

是告诉我们这是哪个领域的么？？