1 files changed, 23 insertions, 9 deletions

diff --git a/subprojects/language/src/main/java/tools/refinery/language/Problem.xtext b/subprojects/language/src/main/java/tools/refinery/language/Problem.xtext
index 0fb96954..f0d6c38c 100644
--- a/subprojects/language/src/main/java/tools/refinery/language/Problem.xtext
+++ b/subprojects/language/src/main/java/tools/refinery/language/Problem.xtext
@@ -1,5 +1,5 @@
 /*
- * SPDX-FileCopyrightText: 2021-2023 The Refinery Authors <https://refinery.tools/>
+ * SPDX-FileCopyrightText: 2021-2024 The Refinery Authors <https://refinery.tools/>
  *
  * SPDX-License-Identifier: EPL-2.0
  */
@@ -9,13 +9,19 @@ import "http://www.eclipse.org/emf/2002/Ecore" as ecore
 import "https://refinery.tools/emf/2021/Problem"
 
 Problem:
-        ("problem" name=Identifier ".")?
+        (kind=ModuleKind name=QualifiedName? ".")?
         statements+=Statement*;
 
+enum ModuleKind:
+        PROBLEM="problem" | MODULE="module";
+
 Statement:
-        Assertion | ClassDeclaration | EnumDeclaration |
+        ImportStatement | Assertion | ClassDeclaration | EnumDeclaration |
         PredicateDefinition | /* FunctionDefinition | RuleDefinition | */
-        ScopeDeclaration | IndividualDeclaration;
+        ScopeDeclaration | NodeDeclaration;
+
+ImportStatement:
+        "import" importedModule=[Problem|QualifiedName] ("as" alias=ID)? ".";
 
 ClassDeclaration:
         abstract?="abstract"? "class"
@@ -252,23 +258,28 @@ RangeMultiplicity:
 ExactMultiplicity:
         exactValue=INT;
 
-IndividualDeclaration:
-        "indiv" nodes+=EnumLiteral ("," nodes+=EnumLiteral)* ".";
+NodeDeclaration:
+        ("declare" | "declare"? kind=NodeKind)
+        nodes+=EnumLiteral ("," nodes+=EnumLiteral)* ".";
+
+enum NodeKind:
+        ATOM="atom" | MULTI="multi";
 
 UpperBound returns ecore::EInt:
         INT | "*";
 
 QualifiedName hidden():
-        Identifier ("::" Identifier)*;
+        "::"? Identifier (QUALIFIED_NAME_SEPARATOR Identifier)*;
 
 NonContainmentQualifiedName hidden():
-        NonContainmentIdentifier ("::" Identifier)*;
+        (NonContainmentIdentifier | "::" Identifier) (QUALIFIED_NAME_SEPARATOR Identifier)*;
 
 Identifier:
         NonContainmentIdentifier | "contains" | "container";
 
 NonContainmentIdentifier:
-        ID | "contained" | "sum" | "prod" | "min" | "max";
+        ID | "atom" | "multi" | "contained" |
+        "sum" | "prod" | "min" | "max" | "problem" | "module";
 
 Real returns ecore::EDouble:
         EXPONENTIAL | INT "." (INT | EXPONENTIAL);
@@ -276,6 +287,9 @@ Real returns ecore::EDouble:
 terminal TRANSITIVE_CLOSURE:
         "synthetic:TRANSITIVE_CLOSURE";
 
+terminal QUALIFIED_NAME_SEPARATOR:
+        "synthetic::QUALIFIED_NAME_SEPARATOR";
+
 @Override
 terminal ID:
         ('a'..'z' | 'A'..'Z' | '_') ('a'..'z' | 'A'..'Z' | '_' | '0'..'9')*;