How to write centered multi-line conclusion in inference rule?

Question

I'm using the semantic package to write inference rules and I have trouble with the following:

\usepackage[inference]{semantic}
\usepackage{amsmath}


\begin{equation}
  \inference{ expr }{ \begin{aligned} long_expr1 \\ long_expr2 \end{aligned} }
\end{equation}

In this code, I want long_expr1 and long_expr2 to be centered. However, the aligned environment aligns them on the right. How can I fix this?

Answer 1

Answering my own question, the problem is solved with the gathered environment.

\begin{equation}
  \inference{ expr }{ \begin{gathered} long_expr1 \\ long_expr2 \end{gathered} }
\end{equation}