Help please

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SANZEED
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Help please

Unread post by SANZEED » Sun Jan 06, 2013 10:44 pm

(This is a direct problem from the book "Combinatorics:A Problem Oriente Approach" by Daniel A. Marcus.)
Find the number of ways to seat $m$ dogs and $n$ cats around a circular table so that the cats are all seoarated from each other.
$\color{blue}{\textit{To}} \color{red}{\textit{ problems }} \color{blue}{\textit{I am encountering with-}} \color{green}{\textit{AVADA KEDAVRA!}}$
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kfoozminus
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Re: Help please

Unread post by kfoozminus » Mon Jan 07, 2013 1:22 pm

first permute $m-1$ dogs keeping fixed $1$ dog, and then permute $n$ cats among $m$ blank seats between the dogs.
$(m-1)!\cdot ^mP_n$
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