Hi, I uploaded two statements (I guess), and I didn't understand them , can someone help me understand why do they do k times Q(n-1,k-1) or k times Q(n-1,k)??? I don't understand the k times part..
And the lecturer wrote to the properties of Q, Q(n,1)=1.... shouldn't that be equal to n? Q is just a letter he picked for bijection functions...Does he mean by Q(n,k), n!/(n-k)!??? I hope my questions are clear enogh
The whole problem seems strange. I am not familiar with the function Q(n, k). A bijection between A and B exists iff n = k. If f is a bijection, then , and is impossible. Not to say that when the vertical bar in the set-builder notation is followed by another bar from an absolute value, the first bar should be changed into, say, a colon.