Fix some typos in the library documentation comments

share/minizinc/std/int_set_channel.mzn

@@ -1,6 +1,6 @@
 /** @group globals.channeling
   Requires that array of int variables \a x and array of set variables \a y
-  are related such that (\a x[\p i] = \p j) ↔ (\p i in \a y[\p j]).
+  are related such that (\a x[\p i] = \p j) if and only if (\p i in \a y[\p j]).
 */
 predicate int_set_channel(array[int] of var int: x,
                           array[int] of var set of int: y) =

share/minizinc/std/link_set_to_booleans.mzn

@@ -1,6 +1,6 @@
 /** @group globals.channeling
   Constrain the array of Booleans \a b to be a representation of the set \a s:
-  \p i in \a s ↔ \a b[\p i].
+  \p i in \a s if and only if \a b[\p i].
 
   The index set of \a b must be a superset of the possible values of \a s.
 */

share/minizinc/std/value_precede_chain.mzn

@@ -5,8 +5,8 @@ include "value_precede_chain_set.mzn";
   Requires that \a c[\p i] precedes \a c[\p i +1] in the array \a x.
 
   Precedence means that if any element of \a x
-  is equal to \a \a c[\p i +1], then another element of \a x with a  lower index is equal
-  to \a \a c[\p i].
+  is equal to \a c[\p i +1], then another element of \a x with a  lower index is equal
+  to \a c[\p i].
 */
 predicate value_precede_chain(array[int] of int: c, array[int] of var int: x) =
     value_precede_chain_int(c, x);
@@ -15,8 +15,8 @@ predicate value_precede_chain(array[int] of int: c, array[int] of var int: x) =
   Requires that \a c[\p i] precedes \a c[\p i +1] in the array \a x.
 
   Precedence means that if an element of \a x
-  contains \a \a c[\p i +1] but not \a \a c[\p i], then another element of \a x with lower index contains
-  \a \a c[\p i] but not \a \a c[\p i +1].
+  contains \a c[\p i +1] but not \a c[\p i], then another element of \a x with lower index contains
+  \a c[\p i] but not \a c[\p i +1].
 */
 predicate value_precede_chain(array[int] of int: c, array[int] of var set of int: x) =
     value_precede_chain_set(c, x);