03/06/2011, 09:41 PM
6. (a + 1)[n]b > a[n]b
Proof:
For n = 1 & 2 lemma 6 is evident.
Let's assume lemma 6 to be true for a given n > 1.
b = 1
=====
(a + 1)[n+1] 1 = a + 1 > a = a [n+1] 1
Assume (a + 1) [n+1] b > a [n+1] b for some b > 0
Then we wish to prove that (a + 1) [n+1] (b + 1) > a [n+1] (b + 1)
This is proved by:
(a + 1) [n+1] (b + 1)
= (a + 1) [n] ((a + 1) [n+1] b)
> (a + 1) [n] (a [n+1] b)
> a [n] (a [n+1] b)
= a [n+1] (b + 1)
This proves lemma 6 for n + 1 by induction applied to b.
So lemma 6 also has been proved for all n by induction applied to n.
Proof:
For n = 1 & 2 lemma 6 is evident.
Let's assume lemma 6 to be true for a given n > 1.
b = 1
=====
(a + 1)[n+1] 1 = a + 1 > a = a [n+1] 1
Assume (a + 1) [n+1] b > a [n+1] b for some b > 0
Then we wish to prove that (a + 1) [n+1] (b + 1) > a [n+1] (b + 1)
This is proved by:
(a + 1) [n+1] (b + 1)
= (a + 1) [n] ((a + 1) [n+1] b)
> (a + 1) [n] (a [n+1] b)
> a [n] (a [n+1] b)
= a [n+1] (b + 1)
This proves lemma 6 for n + 1 by induction applied to b.
So lemma 6 also has been proved for all n by induction applied to n.

