Combination is defined as $C(n,k) = n! / k!(n-k)!$, where n & k are non-negative integers.
Now, the definition can be extend to C(r,k), where r is real number and k is an integer:
C(r,k) = r(r-1)...(r-k+1)/k! , where k>=0; = 1 , where k = 0; = 0 , where k < 0.
Question: is it possible to extend the definition even further, to be based on 2 real numbers, C(r,s), where both r and s are real numbers?