w-knum(w;i;k;t) == sum(if (isnull(a(i;n)))  kind(a(i;n)) = k then 1 else 0 fi  | n < t) 

latex

---

clarification:

w-knum(w;i;k;t)
== sum(if (w-isnull(w; w-a(w; i; n)))  w-kind(w; w-a(w; i; n)) = k
== then 1
== else 0
== fi  | n < t) 

latex

Definitions	sum(f(x) | x < k), if b then t else f fi , p  q, b, isnull(a), a = b, kind(a), a(i;t), #$n
FDL editor aliases	w-knum