In this thread, I couldn't get the following to work.

\begin{pmatrix}x_1\\\vdots\\x_n\end{pmatrix}=\begi n{pmatrix}\alpha\wedge x_1\\\vdots\\\alpha\wedge x_n\end{pmatrix}

It gives

I had to interject "[/tex][tex]" after "=". Why is that?

PS: I have no idea where the space in the second "begin" comes from. It's not there when I edit the text.