Step 3



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Step 3

We have now reduced the proof of theorem 3 to that of establishing

almost surely. We will prove this by establishing

 

almost surely and

 

almost surely.

To prove 9 note that differs from

by a constant not depending on (note that we suppress the dependence of and on ). For fixed this is maximized as a function of by . The profile obtained by replacing by is concave and is maximized over all by . Since this estimate is strongly consistent on the explosion set, the profile is maximized, subject to at one of the two points . Finally, 9 is easily established by considering the two values individually.

Fix and let be the event that for all . Then and is the explosion set except for a -null event. For trajectories in with chosen large we write

 

We will choose and depending on . In particular let

with to be chosen later and

Each is a probability so bounded by 1. Thus

 

The first term in 12 is free of and after division by converges to 0 almost surely on . Also on grows exponentially when and so . From 1 we obtain

 

On we have . Thus, except for a fixed number of (depending only on and ) the right hand side of 13 is less than permitting a Taylor expansion of the . Hence

almost surely.

For the fourth term in 12 we have

 

for all . Letting a Taylor expansion of the logarithm then shows that

which converges to 0 almost surely.

It remains to deal with the second term in 12. This is the most technical part of the argument. Consider now any for which . (Remember that depends on .) There is an for which . There is then a constant not depending on or such that for all small

Since is in the convex hull of the points as runs over and since this convex hull is a regular polygon there is a constant depending only on such that there must exist an with

Finally there is a depending only on such that

 

Let be the set of all such that 15 holds. Note that either and the second term above is 0 or belongs to some . For in and we have

Let

Then

An argument like that at (14) shows that the sequence is asymptotically an iid sequence of uniformly distributed random variables. Using this argument we can establish

Since we can choose so that

With this choice of we can use the lemma to prove

Theorem 3 follows.



next up previous
Next: Discussion Up: Consistency of the Previous: Step 2



Richard Lockhart
Thu Oct 26 23:26:04 PDT 1995