I am having trouble getting the qed symbol at the end of my equation, the symbol ends up on the next line. I have tried using the \qedhere command, but that doesn't work in the eqnarray* environment. How do I get around that issue?

```
\begin{proof}
The DM's expected payoff with threshold $t$ and discount factor $\delta $ is%
\begin{eqnarray*}
&&\sum_{i=0}^{\infty }\left( \delta F\left( t\right) ^{n}\right) ^{i}\left(
1-F\left( t\right) ^{n}\right) E\left[ \theta |\theta >t\right] \\
&=&\frac{1-F\left( t\right) ^{n}}{1-\delta F\left( t\right) ^{n}}E\left[
\theta |\theta >t\right]
\end{eqnarray*}%
while each expert's expected payoff is%
\begin{eqnarray*}
&&\sum_{i=0}^{\infty }\left( \delta F\left( t\right) ^{n}\right) ^{i}\left(
1-F\left( t\right) \right) A\left( t\right) E\left[ \theta |\theta >t\right]
\\
&=&\frac{\left( 1-F\left( t\right) \right) A\left( t\right) E\left[ \theta
|\theta >t\right] }{1-\delta F\left( t\right) ^{n}}\text{.}
\end{eqnarray*}%
Eliminating common terms the result then follows since%
\begin{eqnarray*}
\frac{1-F\left( t\right) ^{n}}{1-F\left( t\right) }=\sum_{i=0}^{n-1}F\left(
t\right) ^{i}=n\text{ }A\left( t\right)\text{.}
\end{eqnarray*}
\end{proof}
```

## Best Answer

First and most important:

usenever`eqnarray`

for any reason whatsoever.Second: never leave a blank line before a display.

Third: LaTeX doesn't force anybody to use

`\left`

and`\right`

in front of each parenthesis or bracket; if your editor does it automatically, disable the feature.Fourth: from the chosen breaks, I guess you're writing in a two column format; for this case,

`multline`

is the environment to choose.Fifth:

`amsthm`

provides`\qedhere`

just for this case. It works in every`amsmath`

alignment and in`equation`

, but not with`eqnarray`

. Since you're not going to use`eqnarray`

any moreā¦Note also

`\mid`

instead of`|`

for getting the proper spacing.An alternative to

`multiline`

is`align`

, but I would prefer the above solution.Here are a couple of suggestions about how to modify the appearance.

Use whatever you like instead of

`$\clubsuit$`

.