\doc{Proofs by well-founded induction}
To prove a formula \fq{F} by well-founded induction over a variable \fq{x} of
sort \fq{S} using a relation \fq{R} that has been
\dlink{../commands/assert}{asserted} or \dlink{of-ir}{proved} to be
well founded, LP generates a single subgoal that involves proving the formula
\fq{F(xc)} using the additional hypothesis \fq{R(x, xc) => F(x)}, where \fq{xc}
is a new \llink{constant}{constant} of sort \fq{S}.  

\head{2}{Example}
\begin{verbatim}
assert well founded <
prove 0 + x = x by induction

  New constant:         xc
  Induction subgoal:    0 + xc = xc
  Induction hypothesis: x < xc => 0 + x = x
\end{verbatim}
