I am trying to write the following equation but overfull \hbox will appear after running LaTeX to get a pdf. Could you please help me to write it in a proper way. Many thanks.
$$
(v_{-n}\dots v_{-1} \otimes v_{0} \otimes v_{1}\dots v_{m}) \dashv
(w_{-p}\dots w_{-1} \otimes w_{0} \otimes w_{1} \dots w_{q})\\
&=v_{-n}\dotsv_{-1} \otimes v_{0} \otimes v_{1} \dots v_{m}w_{-p}\dots
w_{q}
$$.
I recommend you use the amsmath package and \[ … \] instead of $$, as described here, or choose any other amsmath environments. I chose multline* for an environment since your & alignment was aligning to nothing.
\documentclass[12pt,oneside,a4paper]{article}
\usepackage{amsmath,amssymb}
\begin{document}
\begin{multline*}
(v_{-n}\dots v_{-1} \otimes v_{0} \otimes v_{1}\dots v_{m}) \mathbin\dashv (w_{-p}\dots w_{-1} \otimes w_{0} \otimes w_{1} \dots w_{q})\\
=v_{-n}\dots v_{-1} \otimes v_{0} \otimes v_{1} \dots v_{m}w_{-p}\dots w_{q}
\end{multline*}
\end{document}
Please mind that you had many typos in the code. Also, as @egreg points out, \dashv needs to be prefixed with \mathbin to yield a binary operator, with proper spacing
\dashv is defined in the kernel, but it's a relation symbol and it seems to be used here as a binary operation, so \mathbin\dashv
– egreg
Jun 01 '17 at 20:18
\documentclass{...}and ending with\end{document}. – Moriambar Jun 01 '17 at 20:09\[...\]preferable to$$...$$? – Werner Jun 01 '17 at 20:12