n,m:
, f:(n
m). Inj(n; m; f) 
n
mn,k:, c:(nk). 
p:(k( List)). sum(||p(j)|| | j < k) = n & (j:k, x,y:||p(j)||. x < y (p(j))[x] > (p(j))[y]) & (j:k, x:||p(j)||. (p(j))[x] < n & c((p(j))[x]) = j)k,b:, f:(k
). (x:k. f(x)b) sum(f(x) | x < k)b
k