急急急~双变量柏松(Bivariate Poisson)

shiyiming

<!-- s:? --><img src="{SMILIES_PATH}/icon_confused.gif" alt=":?" title="Confused" /><!-- s:? --> 在下尝试修改双变量柏松（意：两个不独立的柏松），请问有哪位可以指教吗？请问在下是否有写错呢？

[img:3unxqa5r]http&#58;//www&#46;madio&#46;cn/math/attachment&#46;php?aid=6400&amp;k=a9874d317b5205648b87334d9f2ab091&amp;t=1241739264&amp;fid=44&amp;nothumb=yes&amp;sid=393e4DL3JRFMkTmy90nlwnTe37EyZEDOZvupm9wzpFNll8g[/img:3unxqa5r]

shiyiming

请问哪位兄台可以证实双变量柏松的期望值是否如下呢？

Poisson(x1)
Poisson(x2)
Poisson(x3)=cov(X,Y)

X~Pois(x1+x3)
Y~Pois(x2+x3)

[img:hyb29dw7]http&#58;//kbs&#46;cnki&#46;net/forums/UploadFiles/UserUploads/ryusukekenji/da3c08ab-ab2d-409b-994c-92829384a554&#46;jpg[/img:hyb29dw7]

shiyiming

[img:14veja1j]http&#58;//www&#46;mathchina&#46;com/cgi-bin/attachment&#46;cgi?forum=1&amp;topic=1056&amp;postno=4&amp;name=PoissonLogLikeli_1243393584&amp;type=&#46;jpg[/img:14veja1j]

~
[img:14veja1j]http&#58;//www&#46;flykaoyan&#46;com/images/smilies/paopaobing/xnyucai%20(138)&#46;gif[/img:14veja1j] 求救，请问有谁可以解答在下附件上的方程？