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More integration techniques

In this section the reader is led quickly via a series of integration theorems to the the next section where the theorems are applied.

. If tex2html_wrap_inline16765, i=1,2, and tex2html_wrap_inline16769 then

(9.1)
equation7700

(9.2)
equation7708

Proof: (9.1) Apply theorem 2, noting that tex2html_wrap_inline16771. (9.2) Apply theorem 2 noting that tex2html_wrap_inline16773. Both for tex2html_wrap_inline16775.

. If tex2html_wrap_inline16765, i=1,2, and tex2html_wrap_inline16769 then

(10.1)
eqnarray7720

(10.2)
eqnarray7733

Proof: (10.1) Write the convolution in its integral form and compare with equation 9.117 of appendix 9.4. (10.2) Substitute tex2html_wrap_inline16783 in the result for (10.1).

. If tex2html_wrap_inline16785, and tex2html_wrap_inline16787 then
eqnarray7753

Proof: Apply theorem 10.1 to find the result for the first convolution, then use the series representation for tex2html_wrap_inline16789 for the second convolution, comparing the result with the definition of tex2html_wrap_inline16791 in appendix 9.4. Convolving the series term-by-term is ok since the series is uniformly convergent on [0,1].

Theorem 12 presents preliminary results for the non-overlapping case.

. If the subsets tex2html_wrap_inline16697 defined for tex2html_wrap_inline16797, satisfy tex2html_wrap_inline16799 for all tex2html_wrap_inline16801 and if tex2html_wrap_inline16803 for tex2html_wrap_inline16797, and if tex2html_wrap_inline16807 for tex2html_wrap_inline13113 then
equation7779

Proof: Assume k=1 and tex2html_wrap_inline16817 to begin. Apply tex2html_wrap_inline16819 with respect to tex2html_wrap_inline16821 to the integral (see appendix 9.6.1 for the definition of the T transform) and evaluate the inner T transform. Noting tex2html_wrap_inline16827 and that tex2html_wrap_inline16829 for tex2html_wrap_inline16831, find
equation7794
(See appendix 9.7.1 for the justification of the interchange the integral over tex2html_wrap_inline16159 and the T transform.) Now, write the transformed integral above as the convolution
equation7809
Use theorem 9.1 9.55 and induction to find (with tex2html_wrap_inline16843)
equation7818
Similarly, use theorem 9.2 and induction to find
equation7826
Substituting the last two expressions into tex2html_wrap_inline16845 yields
equation7835
The tex2html_wrap_inline16851 transform may now be taken to find (see appendix 9.4,9.7)
equation7840
Now apply theorem 9.1 in this expression to find for tex2html_wrap_inline16817
equation7845
Refer to appendix 9.8 for the continuation to tex2html_wrap_inline16863. Refer to appendix 9.9 for the existence conditions. Now, for k>1 apply the identity operator tex2html_wrap_inline16819 k times (with respect to tex2html_wrap_inline16871 respectively) and evaluate only the T transforms initially. Since tex2html_wrap_inline16799 for tex2html_wrap_inline16801, the convolution form of the transformed integral becomes
equation7851
Now extend the application of theorem 9.2 to the k convolution products tex2html_wrap_inline16883 for tex2html_wrap_inline16797. Do the substitutions and take the inverse T transforms to find the result. QED.

Appendix 9.5 contains a derivation of an interesting identity based on an alternate form of the result in theorem 12.

Theorem 13 applies theorem 12 to find non-overlap results needed specifically for the expression of Bayes' estimators for the first two moments of the entropy, mutual information, and various other functions.

. If the subsets tex2html_wrap_inline16697 defined for tex2html_wrap_inline16797, satisfy tex2html_wrap_inline16799 for all tex2html_wrap_inline16801 and if tex2html_wrap_inline16803 for tex2html_wrap_inline16797, and if tex2html_wrap_inline16807 for tex2html_wrap_inline13113 then the following hold

(13.1) One logarithm subset sum.
eqnarray7871

(13.2) Two logarithms of subset sums, different subsets.
eqnarray7888

(13.3) Squared logarithm of a subset sum.
eqnarray7910

Proof: The proof is done for theorem 13.1; theorem 13.2 and 13.3 follow in a similar manner. Differentiate both sides of the formula for tex2html_wrap_inline16917 given in theorem 12 with respect to tex2html_wrap_inline16735 using the fact that tex2html_wrap_inline16921. (See appendix 9.7.2 for justification of the interchange the integral and derivative.) Doing this gives the desired result. QED.

Theorems 12 and 13 dealt with non-overlap sums. Theorems 14 and 15 below discuss pair-wise overlap sums. In theorem 14a the non-contained overlap case is discussed. In theorem 14b the contained overlap case is discussed. See appendix 9.4 for the definition of the hypergeometric function tex2html_wrap_inline16923 .

. If the subsets tex2html_wrap_inline16925 and tex2html_wrap_inline16927 satisfy tex2html_wrap_inline16929tex2html_wrap_inline16931tex2html_wrap_inline16933tex2html_wrap_inline16935, and tex2html_wrap_inline16807tex2html_wrap_inline13113, then
eqnarray7951

Proof: To begin, assume that tex2html_wrap_inline16945, i=1,2, and that the tex2html_wrap_inline16949 are not integers. Apply tex2html_wrap_inline16951 (tex2html_wrap_inline16953 is with respect to tex2html_wrap_inline16949, see appendix 9.6.1) to the integral tex2html_wrap_inline16957. Evaluating the (non-inverse) T transforms yields the convolution (see theorem 1)
eqnarray7982
(See appendix 9.7.1 for justification of the interchange of the integral over tex2html_wrap_inline16159 and the T transform.) Apply theorem 9.1 and induction to find (where tex2html_wrap_inline16967)
eqnarray8011
Similarly, use theorem 9.2 and induction to find
eqnarray8025
Substitute the result for theorem 11 into the triple convolution above, and substitute the last two expressions into the convolution form of the transformed integral to find
eqnarray8058
Now, take inverse T transforms and apply theorem 9.1 to find the desired result. Refer to appendix 9.9 to determine the conditions for the existence of the identity. Refer to appendix 9.8 for the continuation of the result to tex2html_wrap_inline16975. Finally, for values of tex2html_wrap_inline16977, refer to appendix 9.10. QED.

See appendix 9.5 for a derivation of two interesting identities resulting from alternate forms of this proof. When tex2html_wrap_inline16979 the above result simplifies as in theorem 14b below.

. If the subsets tex2html_wrap_inline16981 satisfy tex2html_wrap_inline16929tex2html_wrap_inline16979tex2html_wrap_inline16987tex2html_wrap_inline16989, and tex2html_wrap_inline16807tex2html_wrap_inline13113, then

14b.1
eqnarray8096

14b.2
eqnarray8115

Proof: Similar to proof of theorem 14a, but apply theorem 10.1 instead of theorem 11. The second form (theorem 14b.2) of the result is derived by applying Gauss's identity (see appendix 9.5) to the first form of the result above. QED.

Theorems 15a and 15b build upon the results of theorems 14a and 14b respectively and state results needed to express specific terms of the various Bayes' estimators. Theorem 15a contains results for the non-contained overlap case. Theorem 15b contains results for the contained overlap case. Since we are most directly interested in non-negative integer tex2html_wrap_inline14461's and because simplification occurs at those tex2html_wrap_inline14461's, Theorem 15a is stated only for non-negative integer tex2html_wrap_inline14461's.

. If tex2html_wrap_inline17009 and tex2html_wrap_inline17011 are integers and the conditions for theorem 14a hold then

15a.1
eqnarray8134

15a.2
eqnarray8143

15a.3
eqnarray8152

15a.4
eqnarray8161
where
eqnarray8170
and

(a)
eqnarray8191

(b)
eqnarray8202
with tex2html_wrap_inline17023 given by
eqnarray8212

(c) tex2html_wrap_inline17025 is the same as (b) with tex2html_wrap_inline17027 and tex2html_wrap_inline17029.

(d)
eqnarray8223

(e)
eqnarray8232
with tex2html_wrap_inline17031 given by
eqnarray8242

Proof: The proof is done for theorem 15a.2. The other cases have similar proofs. Differentiate both sides of the expression for tex2html_wrap_inline16957 given in theorem 14a with respect to tex2html_wrap_inline16821. After differentiating, the left-hand side is given by tex2html_wrap_inline17037. (The justification of the interchange of the integral and derivative is given in appendix 9.7.1.) Write the differentiated right-hand side as
equation8270
This expands totex2html_wrap_inline17039. The derivative of tex2html_wrap_inline17041 is given by tex2html_wrap_inline17043. The undifferentiated hypergeometric is evaluated at tex2html_wrap_inline16821 and tex2html_wrap_inline17047 using the results in appendix 9.10, cases 1 and 2. This evaluates to tex2html_wrap_inline17049 defined in (a) above. The derivative of the hypergeometric may be taken term-by-term (this is justified below). Use the results in appendix 9.10, cases 1 and 2, equations 9.144 and 9.147, to evaluate this derivative tex2html_wrap_inline16821 and tex2html_wrap_inline17047. Doing this gives the expression tex2html_wrap_inline17055 defined in (b). With these derivatives and evaluations, theorem 15a.2 follows immediately. Now consider the validity of term-by-term differentiation of the hypergeometric. There exists a closed neighborhood N containing the integer tex2html_wrap_inline16821 with tex2html_wrap_inline17061tex2html_wrap_inline17063. The results of appendix 9.10 show that any truncation (in j) of the series for tex2html_wrap_inline17067 (see appendix 9.4) may be differentiated with respect to x on N. The sequence of derivatives of the increasing order truncations converges uniformly on N. (To see this, note that tex2html_wrap_inline17075 is convergent for each i, and tex2html_wrap_inline17079. Now, note that tex2html_wrap_inline17081 is a series of terms each monotonic on N with the same monotonicity in x holding for each term, and that the summation over i in (b) is finite. These observations and the convergence just established demonstrate the claim of uniform convergence.) Finally, by theorem 7.17 of [73], the sequence of derivatives of the increasing order truncations converges to the derivative of the limit of the series on N, justifying the term-by-term differentiation of the infinite series. QED.

See appendix 9.5 for some comments regarding alternate forms for the results given above in theorem 15a. Theorem 15b builds on theorem 14b and states the results for the case in which there are two subset sums, with the indices of one subset completely contained in the other. Here, unlike in theorem 15a, there is no hypergeometric function to consider, so the presentation of these results is much shorter. Further, unlike theorem 15a, the expressions given are valid for all tex2html_wrap_inline14461's in the range specified (not just at nonnegative integers as in theorem 15a) because there are no poles in the expressions being considered at the integers and therefore no further simplification occurs at these points.

. If the conditions for theorem 14b hold, then

15b.1
eqnarray8311

15b.2
eqnarray8325

15b.3
eqnarray8348

15b.4
eqnarray8383

15b.5
eqnarray8402
where
eqnarray8441

Proof: The proof is done for theorem 15b.2. The proofs of the other results follow in a similar manner. The result of theorem 14b is
eqnarray8451
Differentiate both sides of this with respect to tex2html_wrap_inline17047. The left-hand side of the differentiated expression is tex2html_wrap_inline17111. (The justification of the interchange of the integral and derivative is given in appendix 9.7.2.) The derivative of tex2html_wrap_inline17113 is given by tex2html_wrap_inline17115. The derivative of tex2html_wrap_inline17117 is given by tex2html_wrap_inline17119. Substituting these expressions for the appropriate derivatives in the overall derivative of the right-hand side of the equality above for tex2html_wrap_inline17121 gives the claimed result. QED.


nextuppreviouscontents
Next:Estimators for functions involving Up:Estimating functions of probability Previous:Extended notation for more
David Wolf

Tue Mar 25 08:11:49 CST 1997