# Vertical space around \vdots in xymatrix

I'm trying to create a diagram using \xymatrix but cannot find a way to get rid of the excess vertical space above \vdots - does anyone have any suggestions?

\documentclass[10pt,a4paper,twoside]{article}
\usepackage{amsmath, amssymb}
\usepackage{amsthm}
\input xy
\xyoption{all}

\begin{document}

$\xymatrix @R=1pc @C=2.5pc{ B_t(\zeta) \ar@{-}[d] \\ \vdots \ar@{-}[d] \\ B_2(\zeta) \ar@{-}[d] \\ B_1(\zeta) \ar@{-}[d] \\ F(\zeta) \ar@{-}[d] \\ F }$

\end{document}


Playing with both optional arguments of \raisebox you can control the white space above and below the vdots:

\documentclass[10pt,a4paper,twoside]{article}
\usepackage{amsmath, amssymb}
\usepackage{amsthm}
\input xy
\xyoption{all}

\begin{document}

$\xymatrix @R=1pc @C=2.5pc{ B_t(\zeta) \ar@{-}[d]\\ \raisebox{0pt}[0.9\height][0.3\height]{ \vdots } \ar@{-}[d] \\ B_2(\zeta) \ar@{-}[d] \\ B_1(\zeta) \ar@{-}[d] \\ F(\zeta) \ar@{-}[d] \\ F }$
\end{document}


The same with a simple array:

\documentclass{article}
\usepackage{amsmath}
\begin{document}

$\begin{array}{c} B_t(\zeta)\\\vrule\\[-2pt] \vdots \\\vrule\\ B_2(\zeta)\\\vrule\\ B_1(\zeta)\\\vrule\\ F(\zeta) \\\vrule\\ F \end{array}$

\end{document}


Define a new \myvdots instead of \vdots as follows:

\documentclass[10pt,a4paper,twoside]{article}
\usepackage{amsmath, amssymb}
\usepackage{amsthm}
\usepackage[all]{xy}
\newcommand{\myvdots}{\raisebox{.006\baselineskip}{\ensuremath{\vdots}}}

\begin{document}

$\xymatrix @R=1pc @C=2.5pc{ B_t(\zeta) \ar@{-}[d] \\ \myvdots \ar@{-}[d] \\ B_2(\zeta) \ar@{-}[d] \\ B_1(\zeta) \ar@{-}[d] \\ F(\zeta) \ar@{-}[d] \\ F }$

\end{document}


And the effective is

By the way, for xy, please use the neat codes \usepackage[all]{xy}.