Q: pmatrix and vdots are not aligned between rows Consider the following code to create a matrix
\documentclass{svmult}
\usepackage{amssymb,amsmath,amsfonts}
\usepackage{mathtools}
\usepackage{bm}
\usepackage{tikz}    
\usetikzlibrary{arrows,trees,decorations,external,positioning,backgrounds}
\sloppy
\begin{document}
\begin{equation*}
  Y = 
  \begin{pmatrix}
    1  & 0 & \hdots & \hdots & 0
    \\
    1 & 0 & & & \vdots
    \\
    0 & 1 & \ddots & & \vdots
    \\
    \vdots & \ddots & \ddots  & \ddots & \vdots
    \\
   \vdots &   & \ddots & 1 & 0 
    \\
    0 & \hdots & \hdots & 0 &  1 
  \end{pmatrix}
\end{equation*}
\end{document}

The output is the following

What I would like to correct is the fact that several ddots are not aligned in the sense there is no one straight line passing through these dots.
In particular, the diagonal dots of the third and fourth row and the 1 and 0 of the second last row are not aligned (ddot) 
EdIT: Here is the class file is available here :
class file

A: Here's a workaround, adding a small negative vertical space between  well-chosen rows. I also used \hdotsfor{2} rather than two consecutive \hdots.  To have similar  continuous or diagonal  vertical dots, you can use  the nicematrix package, based on TikZ.
\documentclass{article}

\usepackage{amsmath}

\begin{document}

  \begin{equation*}
  Y =
  \begin{pmatrix}
    1 & 0 & \hdotsfor{2}& 0
    \\
    1 & 0 & & & \vdots
    \\[-0.5ex]
    0 & 1 & \ddots & & \vdots
    \\[-0.5ex]
    \vdots & \ddots & \ddots & \ddots & \vdots
    \\[-0.5ex]
   \vdots & & \ddots & 1 & 0
    \\
    0 & \hdotsfor{2} & 0 & 1
  \end{pmatrix}
 \end{equation*}

\end{document} 


