2

I want to align two columns in an equation next to each other with no space. I am using the following code.

\begin{equation*}
    \begin{aligned}[b]
    N(vw)=N(s_iuw)=N(s_i(uw))
    & = N(s_i) & \Delta \; &  s_iN(uw)s_i \\
    & = N(s_i) & \Delta \; & s_iN(u)s_i \; \Delta \; s_iuN(w)u^{-1}s_i \\
    & = N(v)   & \Delta \; & s_iuN(w)(s_iu)^{-1} \\ 
    & = N(v)   & \Delta \; & vN(w)v^{-1}.
    \end{aligned}
    \qedhere
\end{equation*}

but there's a space between the two columns as below.

enter image description here

How do I get rid of the space?

2
  • 1
    See the alignedat env, note that it takes a mandatory argument which in this case would be 2
    – daleif
    Mar 22, 2020 at 23:21
  • 2
    Is \Delta to be considered as a binary operation symbol?
    – egreg
    Mar 22, 2020 at 23:50

1 Answer 1

3

Judging from all \; commands, your Delta should be considered as a binary operation symbol.

Use alignedat.

\documentclass{article}
\usepackage{amsmath,amsthm}

\newcommand{\bDelta}{\mathbin{\Delta}}

\begin{document}

\begin{proof}
\begin{equation*}
\begin{alignedat}[b]{2}
N(vw)=N(s_iuw)=N(s_i(uw))
  & = N(s_i) && \bDelta s_iN(uw)s_i \\
  & = N(s_i) && \bDelta s_iN(u)s_i \bDelta s_iuN(w)u^{-1}s_i \\
  & = N(v)   && \bDelta s_iuN(w)(s_iu)^{-1} \\
  & = N(v)   && \bDelta vN(w)v^{-1}.
\end{alignedat}\qedhere
\end{equation*}
\end{proof}

\end{document}

enter image description here

2
  • heading shows 2 answers but there is only one answer -- going the virus way
    – js bibra
    Mar 23, 2020 at 0:44
  • @jsbibra there are two deleted answers
    – daleif
    Mar 23, 2020 at 9:49

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