\begin{LTR}
\fbox{
\begin{alltt}
algorithm network simplex;
begin
determine an initial feasible tree structure (T,L,U);
let x be the flow and \(\pi\) be the node petentials
associated with this tree structure;
while some nontree arc violetes the optimality conditions do
begin
select an entering arc(k,l) violating its optimality
conditions;
add arc(k,l) to the tree and determine the leaving
arc(p,q);
perform a tree update and update the solutions
x and \(\pi\);
end;
end;
\end{alltt}
}
\end{LTR}
\fbox{
\begin{alltt}
algorithm network simplex;
begin
determine an initial feasible tree structure (T,L,U);
let x be the flow and \(\pi\) be the node petentials
associated with this tree structure;
while some nontree arc violetes the optimality conditions do
begin
select an entering arc(k,l) violating its optimality
conditions;
add arc(k,l) to the tree and determine the leaving
arc(p,q);
perform a tree update and update the solutions
x and \(\pi\);
end;
end;
\end{alltt}
}
\end{LTR}