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8. Proof of Proposition 2.3<br />

Semiparametric transformation models 163<br />

Part (i) is verified at the end of the proof. To show part (ii), define<br />

D(λ) = �<br />

D(t, u, λ) = �<br />

(−1) m<br />

m≥0<br />

(−1) m<br />

m≥0<br />

m! λm dm,<br />

m! λm Dm(t, u).<br />

The numbers dm and the functions Dm(t, u) are given by dm = 1, Dm(t, u) = k(t, u)<br />

for m = 0. For m≥1 set<br />

� �<br />

dm = . . .<br />

det ¯ dm(s)b(ds1)·. . .·b(dsm),<br />

Dm(t, u) =<br />

�<br />

�<br />

. . .<br />

(s1,...,sm)∈(0,τ]<br />

(s1,...,sm)∈(0,τ]<br />

det ¯ Dm(t, u;s)b(ds1)·. . .·b(dsm),<br />

where for any s = (s1, . . . , sm), ¯ dm(s) is an m×m matrix with entries ¯ dm(s) =<br />

[k(si, sj)], and ¯ Dm(t, u;s) is an (m + 1)×(m + 1) matrix<br />

¯Dm(t, u;s) =<br />

� k(t, u), Um(t;s)<br />

Vm(s;u), ¯ dm(s)<br />

where Um(t;s) = [k(t, s1), . . . , k(t, sm)], Vm(s;u) = [k(s1, u), . . . , k(sm, u)] T .<br />

By Fredholm determinant formula [25], the resolvent of the kernel k is given by<br />

˜∆(t, u, λ) = D(t, u, λ)/D(λ), for all λ such that D(λ)�= 0, so that<br />

� �<br />

dm = . . . det<br />

s1 ,...,sm∈(0,τ]<br />

distinct<br />

¯ dm(s)b(ds1)·. . .·b(dsm),<br />

because the determinant is zero whenever two or more points si, i = 1, . . . , m are<br />

equal. By Fubini theorem, the right-hand side of the above expression is equal to<br />

�<br />

� �<br />

. . .<br />

det ¯ dm(sπ(1), . . . , sπ(m))b(ds1)·. . .·b(dsm)<br />

π<br />

�<br />

= m!<br />

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