[Xy-pic] How to resolve "Command \l already defined ..."

[KIRAVU, C. (MR.)]

My system has installed:

\usepackage[all]{xy}
\usepackage{tikz-cd}

My LaTeX program includes code statements of the type,

\begin{equation}
\xymatrix {A \ar[r]^f & B \ar[r]^{{\Phi} & H }
\end{equation}

On compiling the LaTeX program the error message on console is:

(/usr/local/texlive/2013/texmf-dist/tex/generic/pgf/frontendlayer/tikz/libraries/tikzlibrarymatrix.code.tex)) (./Definitions.tex

./Definitions.tex:32: LaTeX Error: Command \l already defined
         Or name \end… illegal, see p.192 of manual.

See the LaTeX manual or LaTeX Companion for explanation.
Type H<return> for immediate help.
L l.32 \newcommand{\l}{\v(1)}
?

Observation: Upon pressing <return> following the above prompt, the program runs to the end and renders the graph correctly.  However I must do this every time I compile my (long) program.  This intermediate manual intervention is annoying and I would like to automate the compilation.

Question: What could I possibly do or go  to remove the conflicting definition?


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