Re: (1 Combination 2) = 0 -- Better explanation?

HenHanna <HenHanna@devnull.tb> writes:

Python says:  (1 Combination 2) = 0
        Ok... It's Impossible (to do).
             ------- is there a Better explanation?

JB has given you an explanation to do with generalising the algebraic
equations, but there are also simple explanations from first principles.

(5 Combination 0) = 1  <---- This is explained by  Comb(5,0)=Comb(5,5)
                                     in general:   Comb(N,r)=Comb(N,N-r)

I'll write |[5,0]| for this.  In general |[n,m]| is the number of
m-element subsets of a typical set of n elements.  So how many
zero-element subsets of such a set are there?  Just 1.  |[n,0]| = 1.

And how many 2-element subsets of a 1-element set are there?  0, so
|[1,2]| = 0.

--
Ben.