[Cover] [Contents] [Index] Previous page Next Section

Page 238
10.34 Claim 0238-001.gif.
Proof: Suppose by way of contradiction that some scientist M ApaEx*-identifies Image-2402.gif. We show that the existence of such an M implies that Image-2403.gif is Ex*-identifiable, contradicting Corollary 6.11. First, let p* be a program such that
0238-002.gif
Clearly, for each 0238-003.gif, we have that 0238-004.gif and 0238-005.gif. Hence,  j p* is 1-conforming with each member of Image-2404.gif. Next, for each f, define
0238-006.gif
So, if 0238-007.gif, then 0238-008.gif. Also let r be a recursive function such that, for all i and j,  j r(i)(j) =  j i(min(Sj)). So if  j i = f', for some 0238-009.gif, then  j r(i) = f. Finally, let M' be a scientist such that, for each f,
0238-010.gif
As the reader may check, it follows from our assumption on M and the above definitions that M' must 0238-011.gif. Thus we have the desired contradiction.
10.35 Claim Suppose 0238-012.gif. Then 0238-013.gif.
Proof: Let p be a recursive function such that, for each s and x,
0238-014.gif
Also, let M be a scientist such that, for all s and  s , M(s,  s ) = p(s).
Fix some 0238-015.gif and suppose that s is such that  j s is uniformly d-conforming to f. Then it easily follows that, for each j, 0238-016.gif, and hence,  j p(s) = f. Therefore, M UapdEx-identifies f.
Let us contrast the preceding result with the following proposition, showing that Uap-type additional information cannot, in general, compensate for a higher density Ap-type additional information. The proof of this proposition is left to Exercise 10-18.

 
[Cover] [Contents] [Index] Previous page Next Section