--- /dev/null
+#LyX 2.2 created this file. For more info see http://www.lyx.org/
+\lyxformat 508
+\begin_document
+\begin_header
+\save_transient_properties true
+\origin unavailable
+\textclass article
+\use_default_options true
+\begin_modules
+subequations
+\end_modules
+\maintain_unincluded_children false
+\language english
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+\justification true
+\use_refstyle 1
+\index Index
+\shortcut idx
+\color #008000
+\end_index
+\secnumdepth 3
+\tocdepth 3
+\paragraph_separation indent
+\paragraph_indentation default
+\quotes_language english
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+\end_header
+
+\begin_body
+
+\begin_layout Standard
+The
+\family typewriter
+subequations
+\family default
+ environment, provided by the
+\family typewriter
+amsmath
+\family default
+ package, is helpful to group logically-linked equations.
+ For example, the one-speed one-dimensional integro-differential equation
+ with
+\begin_inset Formula $0\le x\le X$
+\end_inset
+
+ and
+\begin_inset Formula $-1\le\mu\le1$
+\end_inset
+
+ shown in Eq.
+\begin_inset space ~
+\end_inset
+
+
+\begin_inset CommandInset ref
+LatexCommand ref
+reference "eq:odoglbe"
+
+\end_inset
+
+ has associated boundary conditions shown in Eqs.
+\begin_inset space ~
+\end_inset
+
+
+\begin_inset CommandInset ref
+LatexCommand ref
+reference "eq:rlbc"
+
+\end_inset
+
+ and
+\begin_inset CommandInset ref
+LatexCommand ref
+reference "eq:vrbc"
+
+\end_inset
+
+.
+\begin_inset Flex Subequations
+status open
+
+\begin_layout Plain Layout
+\begin_inset Formula
+\begin{align}
+\mu\frac{d\psi\left(x,\mu\right)}{dx}+\Sigma_{t}\left(x\right)\psi\left(x,\mu\right) & =\intop_{-1}^{1}\frac{\Sigma_{s}\left(x,\mu'\to\mu\right)}{2}\psi\left(x,\mu'\right)d\mu'+\frac{Q\left(x,\mu\right)}{2},\label{eq:odoglbe}\\
+\psi\left(0,\mu\right) & =\psi\left(0,-\mu\right)\,,\,0<\mu\le1,\label{eq:rlbc}\\
+\psi\left(X,\mu\right) & =0\,,\,-1\le\mu<0.\label{eq:vrbc}
+\end{align}
+
+\end_inset
+
+
+\begin_inset CommandInset label
+LatexCommand label
+name "eq:odoglbeset_aligned"
+
+\end_inset
+
+
+\end_layout
+
+\end_inset
+
+
+\end_layout
+
+\begin_layout Standard
+In the previous case, the equations use the
+\family typewriter
+amsmath
+\family default
+
+\family typewriter
+align
+\family default
+ environment; however, this is not necessary as shown in Eqs.
+\begin_inset space ~
+\end_inset
+
+
+\begin_inset CommandInset ref
+LatexCommand ref
+reference "eq:odoglbenoa"
+
+\end_inset
+
+–
+\begin_inset CommandInset ref
+LatexCommand ref
+reference "eq:vrbcnoa"
+
+\end_inset
+
+.
+
+\begin_inset Flex Subequations
+status open
+
+\begin_layout Plain Layout
+\begin_inset Formula
+\begin{equation}
+\mu\frac{d\psi\left(x,\mu\right)}{dx}+\Sigma_{t}\left(x\right)\psi\left(x,\mu\right)=\intop_{-1}^{1}\frac{\Sigma_{s}\left(x,\mu'\to\mu\right)}{2}\psi\left(x,\mu'\right)d\mu'+\frac{Q\left(x,\mu\right)}{2},\label{eq:odoglbenoa}
+\end{equation}
+
+\end_inset
+
+
+\begin_inset Formula
+\begin{equation}
+\psi\left(0,\mu\right)=\psi\left(0,-\mu\right)\,,\,0<\mu\le1,\label{eq:rlbcnoa}
+\end{equation}
+
+\end_inset
+
+
+\begin_inset CommandInset label
+LatexCommand label
+name "eq:odoglbeset_individual"
+
+\end_inset
+
+
+\begin_inset Formula
+\begin{equation}
+\psi\left(X,\mu\right)=0\,,\,-1\le\mu<0.\label{eq:vrbcnoa}
+\end{equation}
+
+\end_inset
+
+
+\end_layout
+
+\end_inset
+
+
+\end_layout
+
+\begin_layout Standard
+As an alternative to cross-referencing each subequation directly, the group
+ of subequations (i.e., Eq.
+\begin_inset space ~
+\end_inset
+
+
+\begin_inset CommandInset ref
+LatexCommand ref
+reference "eq:odoglbeset_aligned"
+
+\end_inset
+
+ and/or Eq.
+\begin_inset space ~
+\end_inset
+
+
+\begin_inset CommandInset ref
+LatexCommand ref
+reference "eq:odoglbeset_individual"
+
+\end_inset
+
+) can be referenced by placing a label within the subequation inset but
+ outside the equation(s).
+\end_layout
+
+\end_body
+\end_document