Gaps between arrows and labels

Question

I have a question about my diagram. How can I increase the gap between the arrows and the labels? I would like to have more space between the left arrow and the label (2). Thanks for any suggestions.

\documentclass{amsart}
\usepackage{graphicx}
\usepackage[all]{xypic}

\begin{document}
     \begin{equation*}
    \begin{gathered}
    \quad
        \SelectTips{cm}{} \xymatrix@C=4.5em@R=4.5em{ A
       \ar@<-1ex>@{=>}[d] _-{(3)}\ar@<1ex>@{=>}[r]^-{(1)}  & B  
            \ar@<1ex>@{=>}|{{\object@{/}}}[l]^-{(2)}         \\
         C         \ar@<1ex>@{=>}[r] \ar@<-1ex>@{=>}[u] |{\object@{/}}|{}_-{\;(4)}   & D 
     \ar@<1ex>@{=>}[l] \ar@<-1ex>@{=>}[u]_{\;(5)} }
     \end{gathered}
     \end{equation*}
\end{document}

Answer 1

1. You can modify the spacing of labels globally by adding @L=dimen after \xymatrix. In this case remove all additional spaces like \; you've inserted in the code. For example:

   \documentclass{amsart}
   \usepackage{graphicx}
   \usepackage[all]{xy}
   
   \begin{document}
        \begin{equation*}
        \quad
           \SelectTips{cm}{} \xymatrix@L=6pt@C=4.5em@R=4.5em{ A
          \ar@<-1ex>@{=>}[d] _-{(3)}\ar@<1ex>@{=>}[r]^-{(1)}  & B
               \ar@<1ex>@{=>}|{{\object@{/}}}[l]^-{(2)}         \\
            C         \ar@<1ex>@{=>}[r] \ar@<-1ex>@{=>}[u] |{\object@{/}}|{}_-{(4)}   & D
        \ar@<1ex>@{=>}[l] \ar@<-1ex>@{=>}[u]_{(5)} }
        \end{equation*}
   \end{document} 
   

   

2. You can modify the spacing of the single label treating it as an object, that is to say replace ^{...} with ^*modifiers{...}. In your case you will need the modifier +<dimen>, so replace ^-{(2)} with something like ^*+<1em>{^{(2)}} and adjust 1em to your needs. For example:

   \documentclass{amsart}
   \usepackage{graphicx}
   \usepackage[all]{xy}
   
   \begin{document}
        \begin{equation*}
        \quad
           \SelectTips{cm}{} \xymatrix@C=4.5em@R=4.5em{ A
          \ar@<-1ex>@{=>}[d] _-{(3)}\ar@<1ex>@{=>}[r]^-{(1)}  & B
               \ar@<1ex>@{=>}|{{\object@{/}}}[l]^*+<1em>{^{(2)}}         \\
            C         \ar@<1ex>@{=>}[r] \ar@<-1ex>@{=>}[u] |{\object@{/}}|{}_-{\;(4)}   & D
        \ar@<1ex>@{=>}[l] \ar@<-1ex>@{=>}[u]_-{\;(5)} }
        \end{equation*}
   \end{document} 
   

   

Answer 2

They key @L=dimen can be used to change the default margin for labels (see here). Taking out the spaces that you've manually added and adding @L=1.25ex roughly achieves the result that you want, I believe.

You can change the dimension as necessary, however.

\documentclass{amsart}
\usepackage{graphicx}
\usepackage[all]{xypic}

\begin{document}
     \begin{equation*}
    \begin{gathered}
    \quad
        \SelectTips{cm}{} \xymatrix@C=4.5em@R=4.5em@L=1.25ex{ A
       \ar@<-1ex>@{=>}[d] _-{(3)}\ar@<1ex>@{=>}[r]^-{(1)}  & B  
            \ar@<1ex>@{=>}|{{\object@{/}}}[l]^{(2)}         \\
         C         \ar@<1ex>@{=>}[r] \ar@<-1ex>@{=>}[u] |{\object@{/}}|{}_-{(4)}   & D 
     \ar@<1ex>@{=>}[l] \ar@<-1ex>@{=>}[u]_{(5)} }
     \end{gathered}
     \end{equation*}
\end{document}

Answer 3

How about another approach via Tikz-cd? It looks promising.

The arrow distance can be changed via xshift=<dim> and yshift=<dim>.

The node clearance can be changed via inner sep=<dim>.

The label distance can be changed via node [above, below, right, left=<dim>]{label}.

Code

\documentclass[margin=10pt]{standalone}
%\usepackage[margin=1cm]{geometry}
\usepackage{tikz-cd}

\begin{document}

\begin{tikzcd}[row sep=3cm,column sep=3cm,inner sep=3ex]
A   \arrow[thick,Rightarrow,yshift=2ex,]{r}[above=0.5cm]{(1)}        
    \arrow[thick,Leftarrow, xshift=2ex]{d}[description,sloped]{/}[right=0.5cm]{(4)} 
& B \arrow[thick,Rightarrow,yshift=-2ex]{l}[below=0.5cm]{(2)}[description]{/} \\
C   \arrow[thick,Leftarrow, xshift=-2ex]{u}{(3)}   
    \arrow[thick,Leftarrow, yshift=2ex]{r}{}        
& D \arrow[thick,Leftarrow, yshift=-2ex]{l}{}         
    \arrow[thick,Rightarrow,xshift=2ex]{u}[right=0.5cm]{(5)} 
\end{tikzcd}


\end{document}