Horizontal spacing within a Split Equation

Question

I am trying to split an equation across two lines with a single \Bigg parentheses enclosing both lines. I found a way to do that using \split but there is a massive block of white space at the start of the split that I haven't been able to get rid of. Is there a way to remove that white space (or use a different combination of environments to not have it in the first place)?

\begin{equation*}
    d(\{2,3,4\},2) = min \Bigg( \begin{split}
        &d(\{3,4\},3) + w(3,2) = 12 + 6 = 18 \\ 
        &d(\{3,4\},4) + w(4,2) = 8 + 5 = 13 
    \end{split} \Bigg) = 13
\end{equation*}

The above code creates this text

Additionally while I was able to align the d's using an & when I tried to do the same with the equals at the end it didn't work and replaced the "extra alignment tab" with \cr which obviously isn't what I wanted. Is there a way to align at multiple points within a split or only one?

Answer 1

Don't use a split environment. Instead, use an array environment if you prefer tight line spacing or an aligned environment if you prefer more generous line spacing. In any case, do write \min, not just min.

\documentclass{article}
\usepackage{amsmath}  % for aligned env.
\begin{document}

\begin{equation*}
    d(\{2,3,4\},2) = \min 
    \left( \begin{array}{@{}l@{}}
     d(\{3,4\},3) + w(3,2) = 12 + 6 = 18 \\ 
     d(\{3,4\},4) + w(4,2) =  8 + 5 = 13 
    \end{array} \right)  
    = 13
\end{equation*}

\begin{equation*}
    d(\{2,3,4\},2) = \min 
    \left( \begin{aligned}
     d(\{3,4\},3) + w(3,2) &= 12 + 6 = 18 \\ 
     d(\{3,4\},4) + w(4,2) &=  8 + 5 = 13 
    \end{aligned} \right)  
    = 13
\end{equation*}

\end{document}