diff --git a/grammar/src/control.grm b/grammar/src/control.grm
index 89ea3d6ee54..66091a81b97 100644
--- a/grammar/src/control.grm
+++ b/grammar/src/control.grm
@@ -1,5 +1,5 @@
 /**
-h3. Control structures
+h2. Control structures
 
 bq. See [Control structures]
 */
diff --git a/grammar/src/notation.grm b/grammar/src/notation.grm
index 94e4316bc21..dc684f42daf 100644
--- a/grammar/src/notation.grm
+++ b/grammar/src/notation.grm
@@ -21,8 +21,8 @@ alpha{color:blue}*{*{color}beta{color:blue}*}*{color} denotes a nonempty _beta_-
 
 h1. Semicolons
 
-*Up* provides "semicolon inference": syntactically, subsentences (e.g., statements, declarations etc) are separated by
+[Up] provides "semicolon inference": syntactically, subsentences (e.g., statements, declarations etc) are separated by
 the pseudo-token [SEMI|#SEMI], which stands for "semicolon or newline". In most cases, there's no need for semicolons in
-*Up* code.
+[Up] code.
 
 */
diff --git a/idea/src/jet/Library.jet b/idea/src/jet/Library.jet
index 2f4673a74d7..04df29fc7ae 100644
--- a/idea/src/jet/Library.jet
+++ b/idea/src/jet/Library.jet
@@ -7,6 +7,30 @@ namespace typeinfo {
     }
 }
 
+namespace io {
+  fun print(message : Any?)
+  fun print(message : Int)
+  fun print(message : Long)
+  fun print(message : Byte)
+  fun print(message : Short)
+  fun print(message : Char)
+  fun print(message : Boolean)
+  fun print(message : Float)
+  fun print(message : Double)
+
+  fun println(message : Any?)
+  fun println(message : Int)
+  fun println(message : Long)
+  fun println(message : Byte)
+  fun println(message : Short)
+  fun println(message : Char)
+  fun println(message : Boolean)
+  fun println(message : Float)
+  fun println(message : Double)
+
+  fun readLine() : String?
+}
+
 // Can't write a body due to a bootstrapping problem (see JET-74)
 fun Any?.equals(other : Any?) : Boolean// = this === other
 
diff --git a/idea/src/org/jetbrains/jet/lang/resolve/TopDownAnalyzer.java b/idea/src/org/jetbrains/jet/lang/resolve/TopDownAnalyzer.java
index e4761ac25b6..48869941b6c 100644
--- a/idea/src/org/jetbrains/jet/lang/resolve/TopDownAnalyzer.java
+++ b/idea/src/org/jetbrains/jet/lang/resolve/TopDownAnalyzer.java
@@ -275,12 +275,14 @@ public class TopDownAnalyzer {
         List<JetImportDirective> importDirectives = namespace.getImportDirectives();
         for (JetImportDirective importDirective : importDirectives) {
             if (importDirective.isAbsoluteInRootNamespace()) {
-                throw new UnsupportedOperationException();
+                trace.getErrorHandler().genericError(namespace.getNode(), "Unsupported by TDA"); // TODO
+                continue;
             }
             if (importDirective.isAllUnder()) {
                 JetExpression importedReference = importDirective.getImportedReference();
                 if (importedReference != null) {
-                    JetType type = semanticServices.getTypeInferrerServices(trace, JetFlowInformationProvider.THROW_EXCEPTION).getTypeWithNamespaces(namespaceScope, importedReference, false);
+                    JetTypeInferrer.Services typeInferrerServices = semanticServices.getTypeInferrerServices(trace, JetFlowInformationProvider.THROW_EXCEPTION);
+                    JetType type = typeInferrerServices.getTypeWithNamespaces(namespaceScope, importedReference, false);
                     if (type != null) {
                         namespaceScope.importScope(type.getMemberScope());
                     }
diff --git a/idea/src/org/jetbrains/jet/lang/types/JetTypeInferrer.java b/idea/src/org/jetbrains/jet/lang/types/JetTypeInferrer.java
index e3590f64ca8..bab31af7a1c 100644
--- a/idea/src/org/jetbrains/jet/lang/types/JetTypeInferrer.java
+++ b/idea/src/org/jetbrains/jet/lang/types/JetTypeInferrer.java
@@ -539,7 +539,7 @@ public class JetTypeInferrer {
 
             if (someNamed) {
                 // TODO : check that all are named
-                throw new UnsupportedOperationException(); // TODO
+                trace.getErrorHandler().genericError(call.asElement().getNode(), "Named arguments are not supported"); // TODO
 
     //                    result = overloadDomain.getFunctionDescriptorForNamedArguments(typeArguments, valueArguments, functionLiteralArgument);
             } else {
@@ -1093,7 +1093,10 @@ public class JetTypeInferrer {
 
             if (context.expectedReturnType != null && returnedType != null) {
                 if (!semanticServices.getTypeChecker().isSubtypeOf(returnedType, context.expectedReturnType)) {
-                    context.trace.getErrorHandler().typeMismatch(returnedExpression == null ? expression : returnedExpression, context.expectedReturnType, returnedType);
+                    JetType enrichedType = enrichOutType(returnedExpression, returnedType);
+                    if (!semanticServices.getTypeChecker().isSubtypeOf(enrichedType, context.expectedReturnType)) {
+                        context.trace.getErrorHandler().typeMismatch(returnedExpression == null ? expression : returnedExpression, context.expectedReturnType, returnedType);
+                    }
                 }
             }
 
@@ -1570,7 +1573,7 @@ public class JetTypeInferrer {
             condition.accept(new JetVisitor() {
                 @Override
                 public void visitIsExpression(JetIsExpression expression) {
-                    if (conditionValue) {
+                    if (conditionValue && !expression.isNegated() || !conditionValue && expression.isNegated()) {
                         JetPattern pattern = expression.getPattern();
                         result[0] = patternsToDataFlowInfo.get(pattern);
                         if (scopeToExtend != null) {
@@ -2015,12 +2018,13 @@ public class JetTypeInferrer {
             }
         }
 
-        private JetType enrichOutType(JetExpression receiverExpression, JetType receiverType) {
-            VariableDescriptor variableDescriptor = getVariableDescriptorFromSimpleName(receiverExpression);
+        private JetType enrichOutType(JetExpression expression, JetType initialType) {
+            if (expression == null) return initialType;
+            VariableDescriptor variableDescriptor = getVariableDescriptorFromSimpleName(expression);
             if (variableDescriptor != null) {
                 return context.dataFlowInfo.getOutType(variableDescriptor);
             }
-            return receiverType;
+            return initialType;
         }
 
         @Nullable
diff --git a/idea/testData/checker/Nullability.jet b/idea/testData/checker/Nullability.jet
index 770ed4c746b..8479b364cd8 100644
--- a/idea/testData/checker/Nullability.jet
+++ b/idea/testData/checker/Nullability.jet
@@ -272,3 +272,9 @@ fun f8(b : String?, a : String) {
     b.get(0)
   }
 }
+
+fun f9(a : Int?) : Int {
+  if (a != null)
+    return a
+  return 1
+}
\ No newline at end of file
diff --git a/idea/testData/checker/infos/Autocasts.jet b/idea/testData/checker/infos/Autocasts.jet
index 8bfdccd7cea..cd930a4f366 100644
--- a/idea/testData/checker/infos/Autocasts.jet
+++ b/idea/testData/checker/infos/Autocasts.jet
@@ -147,3 +147,9 @@ fun f15(a : A?) {
   <info descr="Automatically cast to B">a</info>.bar()
   <error>c</error>.bar()
 }
+
+fun getStringLength(obj : Any) : Char? {
+  if (obj !is String)
+    return null
+  return <info>obj</info>.get(0) // no cast to String is needed
+}
\ No newline at end of file
diff --git a/stdlib/src/jet/typeinfo/TypeInfo.java b/stdlib/src/jet/typeinfo/TypeInfo.java
index 3ef38ffc45f..50c5dddff3d 100644
--- a/stdlib/src/jet/typeinfo/TypeInfo.java
+++ b/stdlib/src/jet/typeinfo/TypeInfo.java
@@ -37,7 +37,7 @@ public class TypeInfo<T> implements JetObject {
         if (!theClass.isAssignableFrom(other.theClass)) {
             return false;
         }
-        if (nullable != other.nullable) {
+        if (nullable && !other.nullable) {
             return false;
         }
         if (typeParameters != null) {