let negativeClause clause =
List.map
(fun term ->
match term with
| TNot(c) -> c
| TCall _ | TReturn _ | TRel _ -> TNot term
| TTrue -> TFalse
| TFalse -> TTrue
| TAnd (_,_)
| TOr (_,_) -> Aorai_option.fatal "not a DNF clause"
) clause