content_image/312244.jpg content_image/312243.jpg content_image/312242.jpg content_image/312241.jpg
We thus have 

<img src='content_image/312244.jpg'>

by the identity DC − $^{1}$( DC − $^{1}$+ I ) − 1 = ( I + ( DC − $^{1}$) − $^{1}$) − 1 (Henderson and Searle, 1981), which we can use as B$_{T}$$_{l}$$_{+1}$$_{T}$$_{l}$$_{+1}$A − 1 T$_{l}$$_{T$_{l}$}$+ I$_{|}$$_{T}$$_{l}$$_{|}$ is invertible from earlier. Then 

Now 

thus det( A − 1 T$_{l}$$_{+1}$$_{T$_{l}$$_{+1}$}$) > 0 as required, and 

<img src='content_image/312243.jpg'>

<img src='content_image/312242.jpg'>

<img src='content_image/312241.jpg'>

