Bug fix in CNF conversion (from Yuyang).

git-svn-id: https://www.prismmodelchecker.org/svn/prism/prism/trunk@10595 bbc10eb1-c90d-0410-af57-cb519fbb1720

prism/etc/scripts/prism-auto

@@ -668,6 +668,8 @@ if options.logDir and not os.path.isdir(options.logDir):
     print "Log directory \"" + options.logDir + "\" does not exist"
     sys.exit(1)
 if options.nailgun:
+    exitCode = subprocess.Popen([options.ngprism, "--nailgun-help"], stderr=open(os.devnull, 'w')).wait()
+    print exitCode
     os.system(options.prismExec + " -ng &")
     time.sleep(0.5)
 for arg in args:

prism/src/parser/BooleanUtils.java

@@ -133,7 +133,7 @@ public class BooleanUtils
 					return Expression.Or(Expression.Not(a), b);
 				}
 				// Remove iff: a <=> b
-				if (Expression.isImplies(e)) {
+				if (Expression.isIff(e)) {
 					Expression a = (Expression)(e.getOperand1().accept(this));
 					Expression b = (Expression)(e.getOperand2().accept(this));
 					// a <=> b  ==  (a | !b) & (!a | b)