Some representation of literals that will be accepted by minisat. NOTE the representation used by minisat is not based on sign but parity. Do not try to encode negative literals as negative integers.
val make : int -> t
make n creates the literal whose index is
n must be strictly positive. Use
neg to obtain the negation of a literal.
val sign : t -> bool
true if the literal is positive,
false for a negated literal. Invariants:
sign (abs x) = true
sign (neg x) = not (sign x)
val to_int : t -> int
val to_string : t -> string