Major Section: THEORIES
Example:
(theory-invariant (incompatible (:rewrite left-to-right)
                                (:rewrite right-to-left)))
General Form:
(incompatible rune1 rune2)
where rune1 and rune2 are two specific runes.  The arguments are
not evaluated.  Invariant is just a macro that expands into a term
that checks that not both runes are enabled.  See theory-invariant.
 
 