f:(
), n:, i:(n+1). f(n-MinAr(f;i;n)) = f(n) min_ar_sound
(f(n))
i else MinAr(f;i-1;n) fi (recursive)
Thm* f:(), n:, i:(n+1). f(n-MinAr(f;i;n)) = f(n) min_ar_sound
Thm* f:(), n:, i:(n+1), j:(n-i+1).
f(n-i) = f(n) 
MinAr(f;j+i;n) = MinAr(f;j;n-i)+i
min_ar_alt