答案1
我的评论中提到了两种可能性:
\documentclass[twocolumn]{article}
\usepackage{lipsum}
%\usepackage{newtxtext, newtxmath}
\usepackage{nccmath}
\begin{document}
With smaller font as defined by use of the \verb+\medmath+ of \verb+nccmath+ package:
\[\medmath{
b_{d,j}(w_{n},w_{m}) =
\begin{cases}
1,& w_{n},w_{m} \in \{w_{d,j}^{C}, w_{d,j+1}^{C},\dotsc, w_{d,j+s}^{C} \}, \\
0,& \text{else}. \\
\end{cases}}
\]
or with normal font size and new variable for series $\{w_{d,j}^{C}, w_{d,j+1}^{C},\dotsc, w_{d,j+s}^{C}\}$:
\[
b_{d,j}(w_{n},w_{m}) =
\begin{cases}
1,& w_{n},w_{m} \in W_k \\
0,& \text{else}. \\
\end{cases},
\]
where
\[
W_{k} = \{w_{d,j}^{C}, w_{d,j+1}^{C}, ... , w_{d,j+s}^{C} \}
\]
or what your equation should be?
\lipsum
\end{document}