Can someone please refresh my memory on what a 'combinatorial proof' is? I'm having trouble grasping the concept and how to apply it here. Thanks!
There are good examples in the book that are used to prove Pascal's Identity and Vandermonde's Identity (pgs 366-367). It's really more about explaining the types of combinations you're considering and the number of possibilities there are rather than using algebra to manipulate numbers / equations. Sorry, I know that was a horrible explanation, but hopefully the book will help you out more. --Rhollowe 16:56, 4 February 2009 (UTC)
