improve documentation for Model:eval.
@@ -38,14 +38,17 @@ public interface Model extends Iterable<ValueAssignment>, AutoCloseable {
/**
* Evaluate a given formula substituting the values from the model and return it as formula.
*
- * <p>If a value is not relevant to the satisfiability result, the model can choose either an
- * arbitrary value (e.g., the value <code>0</code> for the matching type) or just return <code>
- * null</code>.
+ * <p>If a value is not relevant to the satisfiability result, the solver can choose either to
+ * insert an arbitrary value (e.g., the value <code>0</code> for the matching type) or just return
+ * <code>null</code>.
*
- * <p>The formula does not need to be a variable, we also allow complex expression.
+ * <p>The formula does not need to be a variable, we also allow complex expression. The solver
+ * will replace all symbols from the formula with their model values and then simplify the formula
+ * into a simple formula, e.g., consisting only of a numeral expression.
*
- * @param formula Input formula to be evaluated
- * @return evaluation of the given formula or <code>null</code> if the formula has no evaluation
+ * @param formula Input formula to be evaluated.
+ * @return evaluation of the given formula or <code>null</code> if the solver does not provide a
+ * better evaluation.
*/
@Nullable
<T extends Formula> T eval(T formula);
