refactor(language): clarify containment hierarchy

11 files changed, 326 insertions, 88 deletions

diff --git a/subprojects/frontend/package.json b/subprojects/frontend/package.json
index 4ecf2efb..02c6e026 100644
--- a/subprojects/frontend/package.json
+++ b/subprojects/frontend/package.json
@@ -23,7 +23,7 @@
   },
   "homepage": "https://refinery.tools",
   "dependencies": {
-    "@codemirror/autocomplete": "^6.1.1",
+    "@codemirror/autocomplete": "^6.2.0",
     "@codemirror/commands": "^6.1.0",
     "@codemirror/language": "^6.2.1",
     "@codemirror/lint": "^6.0.0",
@@ -39,7 +39,7 @@
     "@lezer/lr": "^1.2.3",
     "@material-icons/svg": "^1.0.33",
     "@mui/icons-material": "5.10.3",
-    "@mui/material": "5.10.4",
+    "@mui/material": "5.10.5",
     "ansi-styles": "^6.1.1",
     "escape-string-regexp": "^5.0.0",
     "lodash-es": "^4.17.21",
@@ -53,7 +53,7 @@
     "react": "^18.2.0",
     "react-dom": "^18.2.0",
     "xstate": "^4.33.6",
-    "zod": "^3.19.0"
+    "zod": "^3.19.1"
   },
   "devDependencies": {
     "@lezer/generator": "^1.1.1",
@@ -61,16 +61,16 @@
     "@types/html-minifier-terser": "^7.0.0",
     "@types/lodash-es": "^4.17.6",
     "@types/ms": "^0.7.31",
-    "@types/node": "^18.7.16",
+    "@types/node": "^18.7.18",
     "@types/prettier": "^2.7.0",
-    "@types/react": "^18.0.19",
+    "@types/react": "^18.0.20",
     "@types/react-dom": "^18.0.6",
-    "@typescript-eslint/eslint-plugin": "^5.36.2",
-    "@typescript-eslint/parser": "^5.36.2",
+    "@typescript-eslint/eslint-plugin": "^5.37.0",
+    "@typescript-eslint/parser": "^5.37.0",
     "@vitejs/plugin-react": "^2.1.0",
     "@xstate/cli": "^0.3.3",
     "cross-env": "^7.0.3",
-    "eslint": "^8.23.0",
+    "eslint": "^8.23.1",
     "eslint-config-airbnb": "^19.0.4",
     "eslint-config-airbnb-typescript": "^17.0.0",
     "eslint-config-prettier": "^8.5.0",
diff --git a/subprojects/frontend/src/language/problem.grammar b/subprojects/frontend/src/language/problem.grammar
index 95861110..7feb6bfe 100644
--- a/subprojects/frontend/src/language/problem.grammar
+++ b/subprojects/frontend/src/language/problem.grammar
@@ -18,7 +18,10 @@ statement {
     (EnumBody { "{" sep<",", IndividualNodeName> "}" } | ".")
   } |
   PredicateDefinition {
-    (ckw<"error"> ckw<"pred">? | ckw<"pred">)
+    (
+      (ckw<"error"> | ckw<"contained"> | ckw<"containment">) ckw<"pred">? |
+      ckw<"pred">
+    )
     RelationName ParameterList<Parameter>?
     PredicateBody { ("<->" sep<OrOp, Conjunction>)?  "." }
   } |
@@ -28,23 +31,29 @@ statement {
     RuleBody { ":" sep<OrOp, Conjunction> "==>" sep<OrOp, Consequent> "." }
   } |
   Assertion {
-    kw<"default">? (NotOp | UnknownOp)? RelationName
+    ckw<"default">? (NotOp | UnknownOp)? RelationName
     ParameterList<AssertionArgument> (":" LogicValue)? "."
   } |
   NodeValueAssertion {
-    IndividualNodeName ":" Constant "."
+    QualifiedName ":" Constant "."
   } |
   IndividualDeclaration {
     ckw<"indiv"> sep<",", IndividualNodeName> "."
   } |
   ScopeDeclaration {
-    kw<"scope"> sep<",", ScopeElement> "."
+    ckw<"scope"> sep<",", ScopeElement> "."
   }
 }
 
 ReferenceDeclaration {
-  (kw<"refers"> | kw<"contains">)?
-  RelationName
+  (
+    ExplicitContainmentReference[@dynamicPrecedence=1] {
+      (ckw<"refers"> | ckw<"contains"> | ckw<"container">) RelationName ~containment
+    } |
+    ImplicitContainmentReference {
+      RelationName ~containment
+    }
+  )
   ("[" Multiplicity? "]")?
   RelationName
   (kw<"opposite"> RelationName)?
diff --git a/subprojects/frontend/src/language/problemLanguageSupport.ts b/subprojects/frontend/src/language/problemLanguageSupport.ts
index 07a884e7..03a7c4cc 100644
--- a/subprojects/frontend/src/language/problemLanguageSupport.ts
+++ b/subprojects/frontend/src/language/problemLanguageSupport.ts
@@ -27,7 +27,8 @@ const parserWithMetadata = parser.configure({
       LineComment: t.lineComment,
       BlockComment: t.blockComment,
       'problem class enum pred rule indiv scope': t.definitionKeyword,
-      'abstract extends refers contains opposite error default': t.modifier,
+      'abstract extends refers contains container opposite': t.modifier,
+      'default error contained containment': t.modifier,
       'true false unknown error': t.operatorKeyword,
       'may must current count': t.operatorKeyword,
       'new delete': t.keyword,
diff --git a/subprojects/frontend/src/theme/ThemeProvider.tsx b/subprojects/frontend/src/theme/ThemeProvider.tsx
index ffb18a06..550b3b30 100644
--- a/subprojects/frontend/src/theme/ThemeProvider.tsx
+++ b/subprojects/frontend/src/theme/ThemeProvider.tsx
@@ -70,8 +70,8 @@ const typography: TypographyVariantsOptions = {
   fontFamily:
     '"InterVariable", "Inter", "Roboto", "Helvetica", "Arial", sans-serif',
   fontWeightMedium: 600,
-  fontWeightEditorNormal: 450,
-  fontWeightEditorBold: 650,
+  fontWeightEditorNormal: 400,
+  fontWeightEditorBold: 700,
   editor: {
     fontFamily:
       '"JetBrains MonoVariable", "JetBrains Mono", "Cascadia Code", "Fira Code", monospace',
@@ -173,7 +173,7 @@ const lightTheme = createResponsiveTheme({
     divider: alpha('#19202b', 0.16),
     outer: {
       background: '#f5f5f5',
-      border: '#d6d7d9',
+      border: '#c8c8c8',
     },
     highlight: {
       number: '#0084bc',
@@ -200,8 +200,8 @@ const lightTheme = createResponsiveTheme({
 const darkTheme = createResponsiveTheme({
   typography: {
     ...typography,
-    fontWeightEditorNormal: 400,
-    fontWeightEditorBold: 600,
+    fontWeightEditorNormal: 350,
+    fontWeightEditorBold: 650,
   },
   components: {
     ...components,
diff --git a/subprojects/language-ide/src/main/java/tools/refinery/language/ide/syntaxcoloring/ProblemSemanticHighlightingCalculator.java b/subprojects/language-ide/src/main/java/tools/refinery/language/ide/syntaxcoloring/ProblemSemanticHighlightingCalculator.java
index 9c061c8f..477940aa 100644
--- a/subprojects/language-ide/src/main/java/tools/refinery/language/ide/syntaxcoloring/ProblemSemanticHighlightingCalculator.java
+++ b/subprojects/language-ide/src/main/java/tools/refinery/language/ide/syntaxcoloring/ProblemSemanticHighlightingCalculator.java
@@ -20,6 +20,7 @@ import tools.refinery.language.model.problem.ClassDeclaration;
 import tools.refinery.language.model.problem.NamedElement;
 import tools.refinery.language.model.problem.Node;
 import tools.refinery.language.model.problem.PredicateDefinition;
+import tools.refinery.language.model.problem.PredicateKind;
 import tools.refinery.language.model.problem.ProblemPackage;
 import tools.refinery.language.model.problem.ReferenceDeclaration;
 
@@ -99,10 +100,12 @@ public class ProblemSemanticHighlightingCalculator extends DefaultSemanticHighli
                 if (eObject instanceof ClassDeclaration classDeclaration && classDeclaration.isAbstract()) {
                         classesBuilder.add(ABSTRACT_CLASS);
                 }
-                if (eObject instanceof ReferenceDeclaration referenceDeclaration && referenceDeclaration.isContainment()) {
+                if (eObject instanceof ReferenceDeclaration referenceDeclaration
+                                && ProblemUtil.isContainmentReference(referenceDeclaration)) {
                         classesBuilder.add(CONTAINMENT_CLASS);
                 }
-                if (eObject instanceof PredicateDefinition predicateDefinition && predicateDefinition.isError()) {
+                if (eObject instanceof PredicateDefinition predicateDefinition
+                                && predicateDefinition.getKind() == PredicateKind.ERROR) {
                         classesBuilder.add(ERROR_CLASS);
                 }
                 if (eObject instanceof Node node) {
diff --git a/subprojects/language-model/problem.aird b/subprojects/language-model/problem.aird
index 9bd76766..60d52cc4 100644
--- a/subprojects/language-model/problem.aird
+++ b/subprojects/language-model/problem.aird
@@ -7,7 +7,7 @@
     <semanticResources>build/resources/main/model/problem.genmodel</semanticResources>
     <ownedViews xmi:type="viewpoint:DView" uid="_CsAAYKA4EeuqkpDnuik1sg">
       <viewpoint xmi:type="description:Viewpoint" href="platform:/plugin/org.eclipse.emf.ecoretools.design/description/ecore.odesign#//@ownedViewpoints[name='Design']"/>
-      <ownedRepresentationDescriptors xmi:type="viewpoint:DRepresentationDescriptor" uid="_CsYa4KA4EeuqkpDnuik1sg" name="problem" repPath="#_CsUwgKA4EeuqkpDnuik1sg" changeId="e743d94a-193b-4553-83d6-610f55227616">
+      <ownedRepresentationDescriptors xmi:type="viewpoint:DRepresentationDescriptor" uid="_CsYa4KA4EeuqkpDnuik1sg" name="problem" repPath="#_CsUwgKA4EeuqkpDnuik1sg" changeId="dcbd311b-404e-4566-9e24-dcd52dba4c23">
         <description xmi:type="description_1:DiagramDescription" href="platform:/plugin/org.eclipse.emf.ecoretools.design/description/ecore.odesign#//@ownedViewpoints[name='Design']/@ownedRepresentations[name='Entities']"/>
         <target xmi:type="ecore:EPackage" href="src/main/resources/model/problem.ecore#/"/>
       </ownedRepresentationDescriptors>
@@ -50,9 +50,9 @@
         <children xmi:type="notation:Node" xmi:id="_c-HCQKA4EeuqkpDnuik1sg" type="2003" element="_c-A7oKA4EeuqkpDnuik1sg">
           <children xmi:type="notation:Node" xmi:id="_c-HCQ6A4EeuqkpDnuik1sg" type="5007"/>
           <children xmi:type="notation:Node" xmi:id="_c-HCRKA4EeuqkpDnuik1sg" type="7004">
-            <children xmi:type="notation:Node" xmi:id="_HjIR8KA5EeuqkpDnuik1sg" type="3010" element="_HjDZcKA5EeuqkpDnuik1sg">
-              <styles xmi:type="notation:FontStyle" xmi:id="_HjIR8aA5EeuqkpDnuik1sg" fontColor="2697711" fontName="Noto Sans" fontHeight="8"/>
-              <layoutConstraint xmi:type="notation:Location" xmi:id="_HjIR8qA5EeuqkpDnuik1sg"/>
+            <children xmi:type="notation:Node" xmi:id="_91XrMDNlEe2fD4dIhR_vzA" type="3010" element="_902GwDNlEe2fD4dIhR_vzA">
+              <styles xmi:type="notation:FontStyle" xmi:id="_91XrMTNlEe2fD4dIhR_vzA" fontColor="2697711" fontName="Noto Sans" fontHeight="8"/>
+              <layoutConstraint xmi:type="notation:Location" xmi:id="_91XrMjNlEe2fD4dIhR_vzA"/>
             </children>
             <styles xmi:type="notation:SortingStyle" xmi:id="_c-HCRaA4EeuqkpDnuik1sg"/>
             <styles xmi:type="notation:FilteringStyle" xmi:id="_c-HCRqA4EeuqkpDnuik1sg"/>
@@ -76,9 +76,9 @@
         <children xmi:type="notation:Node" xmi:id="_fit3kKA5EeuqkpDnuik1sg" type="2003" element="_fihqUKA5EeuqkpDnuik1sg">
           <children xmi:type="notation:Node" xmi:id="_fit3k6A5EeuqkpDnuik1sg" type="5007"/>
           <children xmi:type="notation:Node" xmi:id="_fit3lKA5EeuqkpDnuik1sg" type="7004">
-            <children xmi:type="notation:Node" xmi:id="_sv1ZIKA5EeuqkpDnuik1sg" type="3010" element="_svs2QKA5EeuqkpDnuik1sg">
-              <styles xmi:type="notation:FontStyle" xmi:id="_sv1ZIaA5EeuqkpDnuik1sg" fontColor="2697711" fontName="Noto Sans" fontHeight="8"/>
-              <layoutConstraint xmi:type="notation:Location" xmi:id="_sv1ZIqA5EeuqkpDnuik1sg"/>
+            <children xmi:type="notation:Node" xmi:id="_id6DcDNoEe2fD4dIhR_vzA" type="3010" element="_ida7QDNoEe2fD4dIhR_vzA">
+              <styles xmi:type="notation:FontStyle" xmi:id="_id6DcTNoEe2fD4dIhR_vzA" fontColor="2697711" fontName="Noto Sans" fontHeight="8"/>
+              <layoutConstraint xmi:type="notation:Location" xmi:id="_id6DcjNoEe2fD4dIhR_vzA"/>
             </children>
             <styles xmi:type="notation:SortingStyle" xmi:id="_fit3laA5EeuqkpDnuik1sg"/>
             <styles xmi:type="notation:FilteringStyle" xmi:id="_fit3lqA5EeuqkpDnuik1sg"/>
@@ -219,7 +219,7 @@
             <styles xmi:type="notation:FilteringStyle" xmi:id="_BMfjNqA9EeuqkpDnuik1sg"/>
           </children>
           <styles xmi:type="notation:ShapeStyle" xmi:id="_BMfjMaA9EeuqkpDnuik1sg" fontName="Noto Sans" fontHeight="8"/>
-          <layoutConstraint xmi:type="notation:Bounds" xmi:id="_BMfjMqA9EeuqkpDnuik1sg" x="1917" y="180" width="120" height="100"/>
+          <layoutConstraint xmi:type="notation:Bounds" xmi:id="_BMfjMqA9EeuqkpDnuik1sg" x="1921" y="60" width="120" height="100"/>
         </children>
         <children xmi:type="notation:Node" xmi:id="_QUDYMKA9EeuqkpDnuik1sg" type="2003" element="_QTzgkKA9EeuqkpDnuik1sg">
           <children xmi:type="notation:Node" xmi:id="_QUDYM6A9EeuqkpDnuik1sg" type="5007"/>
@@ -550,7 +550,7 @@
             <styles xmi:type="notation:FilteringStyle" xmi:id="_eKwNAxEKEe2AArBmfNpEZA"/>
           </children>
           <styles xmi:type="notation:ShapeStyle" xmi:id="_eKvl8REKEe2AArBmfNpEZA" fontName="Noto Sans" fontHeight="8"/>
-          <layoutConstraint xmi:type="notation:Bounds" xmi:id="_eKvl8hEKEe2AArBmfNpEZA" x="2072" y="180" width="120" height="100"/>
+          <layoutConstraint xmi:type="notation:Bounds" xmi:id="_eKvl8hEKEe2AArBmfNpEZA" x="2076" y="60" width="120" height="100"/>
         </children>
         <children xmi:type="notation:Node" xmi:id="_BnoHYBg0Ee2_erjsEmF9GQ" type="2003" element="_BmVG4Bg0Ee2_erjsEmF9GQ">
           <children xmi:type="notation:Node" xmi:id="_BnrxwBg0Ee2_erjsEmF9GQ" type="5007"/>
@@ -605,7 +605,57 @@
             <styles xmi:type="notation:FilteringStyle" xmi:id="_LinJ1hg0Ee2_erjsEmF9GQ"/>
           </children>
           <styles xmi:type="notation:ShapeStyle" xmi:id="_LinJ0Rg0Ee2_erjsEmF9GQ" fontName="Noto Sans" fontHeight="8"/>
-          <layoutConstraint xmi:type="notation:Bounds" xmi:id="_LinJ0hg0Ee2_erjsEmF9GQ" x="2223" y="180" width="120" height="111"/>
+          <layoutConstraint xmi:type="notation:Bounds" xmi:id="_LinJ0hg0Ee2_erjsEmF9GQ" x="2232" y="60" width="120" height="111"/>
+        </children>
+        <children xmi:type="notation:Node" xmi:id="_xp1icDNlEe2fD4dIhR_vzA" type="2003" element="_xpDfUDNlEe2fD4dIhR_vzA">
+          <children xmi:type="notation:Node" xmi:id="_xp2JgDNlEe2fD4dIhR_vzA" type="5007"/>
+          <children xmi:type="notation:Node" xmi:id="_xp2JgTNlEe2fD4dIhR_vzA" type="7004">
+            <children xmi:type="notation:Node" xmi:id="_2OW2gDNlEe2fD4dIhR_vzA" type="3010" element="_2N3HQDNlEe2fD4dIhR_vzA">
+              <styles xmi:type="notation:FontStyle" xmi:id="_2OW2gTNlEe2fD4dIhR_vzA" fontName="Noto Sans" fontHeight="8"/>
+              <layoutConstraint xmi:type="notation:Location" xmi:id="_2OW2gjNlEe2fD4dIhR_vzA"/>
+            </children>
+            <children xmi:type="notation:Node" xmi:id="_20SOEDNlEe2fD4dIhR_vzA" type="3010" element="_2zSIgDNlEe2fD4dIhR_vzA">
+              <styles xmi:type="notation:FontStyle" xmi:id="_20SOETNlEe2fD4dIhR_vzA" fontName="Noto Sans" fontHeight="8"/>
+              <layoutConstraint xmi:type="notation:Location" xmi:id="_20SOEjNlEe2fD4dIhR_vzA"/>
+            </children>
+            <children xmi:type="notation:Node" xmi:id="_4LeqgDNlEe2fD4dIhR_vzA" type="3010" element="_4K8fADNlEe2fD4dIhR_vzA">
+              <styles xmi:type="notation:FontStyle" xmi:id="_4LeqgTNlEe2fD4dIhR_vzA" fontName="Noto Sans" fontHeight="8"/>
+              <layoutConstraint xmi:type="notation:Location" xmi:id="_4LeqgjNlEe2fD4dIhR_vzA"/>
+            </children>
+            <children xmi:type="notation:Node" xmi:id="_5M7gcDNlEe2fD4dIhR_vzA" type="3010" element="_5MhQwDNlEe2fD4dIhR_vzA">
+              <styles xmi:type="notation:FontStyle" xmi:id="_5M7gcTNlEe2fD4dIhR_vzA" fontName="Noto Sans" fontHeight="8"/>
+              <layoutConstraint xmi:type="notation:Location" xmi:id="_5M7gcjNlEe2fD4dIhR_vzA"/>
+            </children>
+            <styles xmi:type="notation:SortingStyle" xmi:id="_xp2JgjNlEe2fD4dIhR_vzA"/>
+            <styles xmi:type="notation:FilteringStyle" xmi:id="_xp2JgzNlEe2fD4dIhR_vzA"/>
+          </children>
+          <styles xmi:type="notation:ShapeStyle" xmi:id="_xp1icTNlEe2fD4dIhR_vzA" fontName="Noto Sans" fontHeight="8"/>
+          <layoutConstraint xmi:type="notation:Bounds" xmi:id="_xp1icjNlEe2fD4dIhR_vzA" x="2076" y="204" width="120" height="100"/>
+        </children>
+        <children xmi:type="notation:Node" xmi:id="_DFHboDNoEe2fD4dIhR_vzA" type="2003" element="_DD1pQDNoEe2fD4dIhR_vzA">
+          <children xmi:type="notation:Node" xmi:id="_DFICsDNoEe2fD4dIhR_vzA" type="5007"/>
+          <children xmi:type="notation:Node" xmi:id="_DFICsTNoEe2fD4dIhR_vzA" type="7004">
+            <children xmi:type="notation:Node" xmi:id="_FDz88DNoEe2fD4dIhR_vzA" type="3010" element="_FDOuIDNoEe2fD4dIhR_vzA">
+              <styles xmi:type="notation:FontStyle" xmi:id="_FDz88TNoEe2fD4dIhR_vzA" fontName="Noto Sans" fontHeight="8"/>
+              <layoutConstraint xmi:type="notation:Location" xmi:id="_FDz88jNoEe2fD4dIhR_vzA"/>
+            </children>
+            <children xmi:type="notation:Node" xmi:id="_F3CwsDNoEe2fD4dIhR_vzA" type="3010" element="_F2glMDNoEe2fD4dIhR_vzA">
+              <styles xmi:type="notation:FontStyle" xmi:id="_F3CwsTNoEe2fD4dIhR_vzA" fontName="Noto Sans" fontHeight="8"/>
+              <layoutConstraint xmi:type="notation:Location" xmi:id="_F3CwsjNoEe2fD4dIhR_vzA"/>
+            </children>
+            <children xmi:type="notation:Node" xmi:id="_GTcY0DNoEe2fD4dIhR_vzA" type="3010" element="_GS7bcDNoEe2fD4dIhR_vzA">
+              <styles xmi:type="notation:FontStyle" xmi:id="_GTcY0TNoEe2fD4dIhR_vzA" fontName="Noto Sans" fontHeight="8"/>
+              <layoutConstraint xmi:type="notation:Location" xmi:id="_GTcY0jNoEe2fD4dIhR_vzA"/>
+            </children>
+            <children xmi:type="notation:Node" xmi:id="_GyKVIDNoEe2fD4dIhR_vzA" type="3010" element="_Gx7EkDNoEe2fD4dIhR_vzA">
+              <styles xmi:type="notation:FontStyle" xmi:id="_GyKVITNoEe2fD4dIhR_vzA" fontName="Noto Sans" fontHeight="8"/>
+              <layoutConstraint xmi:type="notation:Location" xmi:id="_GyKVIjNoEe2fD4dIhR_vzA"/>
+            </children>
+            <styles xmi:type="notation:SortingStyle" xmi:id="_DFICsjNoEe2fD4dIhR_vzA"/>
+            <styles xmi:type="notation:FilteringStyle" xmi:id="_DFICszNoEe2fD4dIhR_vzA"/>
+          </children>
+          <styles xmi:type="notation:ShapeStyle" xmi:id="_DFHboTNoEe2fD4dIhR_vzA" fontName="Noto Sans" fontHeight="8"/>
+          <layoutConstraint xmi:type="notation:Bounds" xmi:id="_DFHbojNoEe2fD4dIhR_vzA" x="1921" y="204" width="120" height="100"/>
         </children>
         <styles xmi:type="notation:DiagramStyle" xmi:id="_CsZB8qA4EeuqkpDnuik1sg"/>
         <edges xmi:type="notation:Edge" xmi:id="_4eaYwKA8EeuqkpDnuik1sg" type="4001" element="_4eU5TqA8EeuqkpDnuik1sg" source="_D1D6MKA4EeuqkpDnuik1sg" target="_xsq_MKA8EeuqkpDnuik1sg">
@@ -722,17 +772,17 @@
         </edges>
         <edges xmi:type="notation:Edge" xmi:id="_Vj1sQKA8EeuqkpDnuik1sg" type="4001" element="_VjwMzqA8EeuqkpDnuik1sg" source="_6KEUMKA6EeuqkpDnuik1sg" target="_EfWNUKA4EeuqkpDnuik1sg">
           <children xmi:type="notation:Node" xmi:id="_Vj1sRKA8EeuqkpDnuik1sg" type="6001">
-            <layoutConstraint xmi:type="notation:Bounds" xmi:id="_Vj1sRaA8EeuqkpDnuik1sg" x="-42" y="526"/>
+            <layoutConstraint xmi:type="notation:Bounds" xmi:id="_Vj1sRaA8EeuqkpDnuik1sg" x="-37" y="526"/>
           </children>
           <children xmi:type="notation:Node" xmi:id="_Vj1sRqA8EeuqkpDnuik1sg" type="6002">
-            <layoutConstraint xmi:type="notation:Bounds" xmi:id="_Vj1sR6A8EeuqkpDnuik1sg" x="174" y="-10"/>
+            <layoutConstraint xmi:type="notation:Bounds" xmi:id="_Vj1sR6A8EeuqkpDnuik1sg" x="176" y="-10"/>
           </children>
           <children xmi:type="notation:Node" xmi:id="_Vj1sSKA8EeuqkpDnuik1sg" type="6003">
-            <layoutConstraint xmi:type="notation:Bounds" xmi:id="_Vj1sSaA8EeuqkpDnuik1sg" x="-51" y="10"/>
+            <layoutConstraint xmi:type="notation:Bounds" xmi:id="_Vj1sSaA8EeuqkpDnuik1sg" x="-41" y="10"/>
           </children>
           <styles xmi:type="notation:ConnectorStyle" xmi:id="_Vj1sQaA8EeuqkpDnuik1sg" routing="Rectilinear"/>
           <styles xmi:type="notation:FontStyle" xmi:id="_Vj1sQqA8EeuqkpDnuik1sg" fontColor="7490599" fontName="Noto Sans" fontHeight="8"/>
-          <bendpoints xmi:type="notation:RelativeBendpoints" xmi:id="_Vj1sQ6A8EeuqkpDnuik1sg" points="[-48, 24, 553, 682]$[-720, 24, -119, 682]$[-720, -708, -119, -50]$[-660, -708, -59, -50]"/>
+          <bendpoints xmi:type="notation:RelativeBendpoints" xmi:id="_Vj1sQ6A8EeuqkpDnuik1sg" points="[-48, 24, 553, 682]$[-720, 24, -119, 682]$[-720, -696, -119, -38]$[-660, -696, -59, -38]"/>
           <sourceAnchor xmi:type="notation:IdentityAnchor" xmi:id="_Vj1sSqA8EeuqkpDnuik1sg" id="(0.4067796610169492,0.0)"/>
           <targetAnchor xmi:type="notation:IdentityAnchor" xmi:id="_Vj1sS6A8EeuqkpDnuik1sg" id="(0.5,1.0)"/>
         </edges>
@@ -864,22 +914,6 @@
           <sourceAnchor xmi:type="notation:IdentityAnchor" xmi:id="_-YCtQNawEeuymriYTNxK2g" id="(1.0,0.12244897959183673)"/>
           <targetAnchor xmi:type="notation:IdentityAnchor" xmi:id="_-YCtQdawEeuymriYTNxK2g" id="(0.0,0.6122448979591837)"/>
         </edges>
-        <edges xmi:type="notation:Edge" xmi:id="_2ko-QKA9EeuqkpDnuik1sg" type="4001" element="_2kWqbKA9EeuqkpDnuik1sg" source="_zaq8oKA9EeuqkpDnuik1sg" target="_JT0o8KA4EeuqkpDnuik1sg">
-          <children xmi:type="notation:Node" xmi:id="_2ko-RKA9EeuqkpDnuik1sg" type="6001">
-            <layoutConstraint xmi:type="notation:Bounds" xmi:id="_2ko-RaA9EeuqkpDnuik1sg" x="-53" y="-17"/>
-          </children>
-          <children xmi:type="notation:Node" xmi:id="_2ko-RqA9EeuqkpDnuik1sg" type="6002">
-            <layoutConstraint xmi:type="notation:Bounds" xmi:id="_2ko-R6A9EeuqkpDnuik1sg" x="21" y="10"/>
-          </children>
-          <children xmi:type="notation:Node" xmi:id="_2ko-SKA9EeuqkpDnuik1sg" type="6003">
-            <layoutConstraint xmi:type="notation:Bounds" xmi:id="_2ko-SaA9EeuqkpDnuik1sg" x="3" y="10"/>
-          </children>
-          <styles xmi:type="notation:ConnectorStyle" xmi:id="_2ko-QaA9EeuqkpDnuik1sg" routing="Rectilinear"/>
-          <styles xmi:type="notation:FontStyle" xmi:id="_2ko-QqA9EeuqkpDnuik1sg" fontColor="7490599" fontName="Noto Sans" fontHeight="8"/>
-          <bendpoints xmi:type="notation:RelativeBendpoints" xmi:id="_2ko-Q6A9EeuqkpDnuik1sg" points="[0, 36, -218, 36]$[218, 36, 0, 36]"/>
-          <sourceAnchor xmi:type="notation:IdentityAnchor" xmi:id="_2ko-SqA9EeuqkpDnuik1sg" id="(1.0,0.24742268041237114)"/>
-          <targetAnchor xmi:type="notation:IdentityAnchor" xmi:id="_2ko-S6A9EeuqkpDnuik1sg" id="(0.0,0.24489795918367346)"/>
-        </edges>
         <edges xmi:type="notation:Edge" xmi:id="_0V8EUKA4EeuqkpDnuik1sg" type="4001" element="_0V3L1qA4EeuqkpDnuik1sg" source="_c-HCQKA4EeuqkpDnuik1sg" target="_c-HCQKA4EeuqkpDnuik1sg">
           <children xmi:type="notation:Node" xmi:id="_0V8rYKA4EeuqkpDnuik1sg" type="6001">
             <layoutConstraint xmi:type="notation:Bounds" xmi:id="_0V8rYaA4EeuqkpDnuik1sg" x="30" y="11"/>
@@ -1854,6 +1888,22 @@
           <sourceAnchor xmi:type="notation:IdentityAnchor" xmi:id="_JYvTRBg0Ee2_erjsEmF9GQ" id="(0.3813559322033898,0.0)"/>
           <targetAnchor xmi:type="notation:IdentityAnchor" xmi:id="_JYvTRRg0Ee2_erjsEmF9GQ" id="(0.5,0.5)"/>
         </edges>
+        <edges xmi:type="notation:Edge" xmi:id="_lhC68DOBEe2fD4dIhR_vzA" type="4001" element="_2kWqbKA9EeuqkpDnuik1sg" source="_zaq8oKA9EeuqkpDnuik1sg" target="_EfWNUKA4EeuqkpDnuik1sg">
+          <children xmi:type="notation:Node" xmi:id="_lhC69DOBEe2fD4dIhR_vzA" type="6001">
+            <layoutConstraint xmi:type="notation:Bounds" xmi:id="_lhDiADOBEe2fD4dIhR_vzA" x="-115" y="-29"/>
+          </children>
+          <children xmi:type="notation:Node" xmi:id="_lhDiATOBEe2fD4dIhR_vzA" type="6002">
+            <layoutConstraint xmi:type="notation:Bounds" xmi:id="_lhDiAjOBEe2fD4dIhR_vzA" x="-2" y="10"/>
+          </children>
+          <children xmi:type="notation:Node" xmi:id="_lhDiAzOBEe2fD4dIhR_vzA" type="6003">
+            <layoutConstraint xmi:type="notation:Bounds" xmi:id="_lhDiBDOBEe2fD4dIhR_vzA" x="2" y="10"/>
+          </children>
+          <styles xmi:type="notation:ConnectorStyle" xmi:id="_lhC68TOBEe2fD4dIhR_vzA" routing="Rectilinear"/>
+          <styles xmi:type="notation:FontStyle" xmi:id="_lhC68jOBEe2fD4dIhR_vzA" fontColor="7490599" fontName="Noto Sans" fontHeight="8"/>
+          <bendpoints xmi:type="notation:RelativeBendpoints" xmi:id="_lhC68zOBEe2fD4dIhR_vzA" points="[0, 24, -175, 219]$[85, 24, -90, 219]$[85, -180, -90, 15]$[170, -180, -5, 15]"/>
+          <sourceAnchor xmi:type="notation:IdentityAnchor" xmi:id="_lhGlUDOBEe2fD4dIhR_vzA" id="(1.0,0.24742268041237114)"/>
+          <targetAnchor xmi:type="notation:IdentityAnchor" xmi:id="_lhGlUTOBEe2fD4dIhR_vzA" id="(0.0423728813559322,0.21428571428571427)"/>
+        </edges>
       </data>
     </ownedAnnotationEntries>
     <ownedAnnotationEntries xmi:type="description:AnnotationEntry" uid="_Csiy8KA4EeuqkpDnuik1sg" source="DANNOTATION_CUSTOMIZATION_KEY">
@@ -1880,7 +1930,7 @@
       </ownedStyle>
       <actualMapping xmi:type="description_1:ContainerMapping" href="platform:/plugin/org.eclipse.emf.ecoretools.design/description/ecore.odesign#//@ownedViewpoints[name='Design']/@ownedRepresentations[name='Entities']/@defaultLayer/@containerMappings[name='EC%20EClass']"/>
     </ownedDiagramElements>
-    <ownedDiagramElements xmi:type="diagram:DNodeList" uid="_EfNqcKA4EeuqkpDnuik1sg" name="Relation" tooltipText="" outgoingEdges="_XWbypqA5EeuqkpDnuik1sg" incomingEdges="_ODPlcKA4EeuqkpDnuik1sg _gRoBcKA4EeuqkpDnuik1sg _rUgDkKA5EeuqkpDnuik1sg _VjwMzqA8EeuqkpDnuik1sg _w-iG36A8EeuqkpDnuik1sg _Z7FrQKA6EeuqkpDnuik1sg _ufJ3IKA4EeuqkpDnuik1sg _VtPctqA4EeuqkpDnuik1sg _UwbfHtbGEeuymriYTNxK2g" width="12" height="10">
+    <ownedDiagramElements xmi:type="diagram:DNodeList" uid="_EfNqcKA4EeuqkpDnuik1sg" name="Relation" tooltipText="" outgoingEdges="_XWbypqA5EeuqkpDnuik1sg" incomingEdges="_ODPlcKA4EeuqkpDnuik1sg _gRoBcKA4EeuqkpDnuik1sg _rUgDkKA5EeuqkpDnuik1sg _VjwMzqA8EeuqkpDnuik1sg _w-iG36A8EeuqkpDnuik1sg _Z7FrQKA6EeuqkpDnuik1sg _ufJ3IKA4EeuqkpDnuik1sg _VtPctqA4EeuqkpDnuik1sg _UwbfHtbGEeuymriYTNxK2g _2kWqbKA9EeuqkpDnuik1sg" width="12" height="10">
       <target xmi:type="ecore:EClass" href="src/main/resources/model/problem.ecore#//Relation"/>
       <semanticElements xmi:type="ecore:EClass" href="src/main/resources/model/problem.ecore#//Relation"/>
       <arrangeConstraints>KEEP_LOCATION</arrangeConstraints>
@@ -1892,7 +1942,7 @@
       </ownedStyle>
       <actualMapping xmi:type="description_1:ContainerMapping" href="platform:/plugin/org.eclipse.emf.ecoretools.design/description/ecore.odesign#//@ownedViewpoints[name='Design']/@ownedRepresentations[name='Entities']/@defaultLayer/@containerMappings[name='EC%20EClass']"/>
     </ownedDiagramElements>
-    <ownedDiagramElements xmi:type="diagram:DNodeList" uid="_JTstIKA4EeuqkpDnuik1sg" name="ClassDeclaration" tooltipText="" outgoingEdges="_ODPlcKA4EeuqkpDnuik1sg _VtPctqA4EeuqkpDnuik1sg _jk6-PKA4EeuqkpDnuik1sg _plK3JqA9EeuqkpDnuik1sg _-XLKltawEeuymriYTNxK2g" incomingEdges="_2kWqbKA9EeuqkpDnuik1sg" width="12" height="10">
+    <ownedDiagramElements xmi:type="diagram:DNodeList" uid="_JTstIKA4EeuqkpDnuik1sg" name="ClassDeclaration" tooltipText="" outgoingEdges="_ODPlcKA4EeuqkpDnuik1sg _VtPctqA4EeuqkpDnuik1sg _jk6-PKA4EeuqkpDnuik1sg _plK3JqA9EeuqkpDnuik1sg _-XLKltawEeuymriYTNxK2g" width="12" height="10">
       <target xmi:type="ecore:EClass" href="src/main/resources/model/problem.ecore#//ClassDeclaration"/>
       <semanticElements xmi:type="ecore:EClass" href="src/main/resources/model/problem.ecore#//ClassDeclaration"/>
       <arrangeConstraints>KEEP_LOCATION</arrangeConstraints>
@@ -1943,14 +1993,14 @@
       <arrangeConstraints>KEEP_LOCATION</arrangeConstraints>
       <arrangeConstraints>KEEP_SIZE</arrangeConstraints>
       <arrangeConstraints>KEEP_RATIO</arrangeConstraints>
-      <ownedStyle xmi:type="diagram:FlatContainerStyle" uid="_IMjpcqA5EeuqkpDnuik1sg" borderSize="1" borderSizeComputationExpression="1" backgroundStyle="Liquid" foregroundColor="255,252,216">
+      <ownedStyle xmi:type="diagram:FlatContainerStyle" uid="__Bk_ojNlEe2fD4dIhR_vzA" borderSize="1" borderSizeComputationExpression="1" backgroundStyle="Liquid" foregroundColor="255,252,216">
         <description xmi:type="style:FlatContainerStyleDescription" href="platform:/plugin/org.eclipse.emf.ecoretools.design/description/ecore.odesign#//@ownedViewpoints[name='Design']/@ownedRepresentations[name='Entities']/@defaultLayer/@containerMappings[name='EC%20EClass']/@style"/>
       </ownedStyle>
       <actualMapping xmi:type="description_1:ContainerMapping" href="platform:/plugin/org.eclipse.emf.ecoretools.design/description/ecore.odesign#//@ownedViewpoints[name='Design']/@ownedRepresentations[name='Entities']/@defaultLayer/@containerMappings[name='EC%20EClass']"/>
-      <ownedElements xmi:type="diagram:DNodeListElement" uid="_HjDZcKA5EeuqkpDnuik1sg" name="containment : EBoolean = false" tooltipText="">
-        <target xmi:type="ecore:EAttribute" href="src/main/resources/model/problem.ecore#//ReferenceDeclaration/containment"/>
-        <semanticElements xmi:type="ecore:EAttribute" href="src/main/resources/model/problem.ecore#//ReferenceDeclaration/containment"/>
-        <ownedStyle xmi:type="diagram:BundledImage" uid="_IMmswaA5EeuqkpDnuik1sg" labelAlignment="LEFT">
+      <ownedElements xmi:type="diagram:DNodeListElement" uid="_902GwDNlEe2fD4dIhR_vzA" name="kind : ReferenceKind = DEFAULT" tooltipText="">
+        <target xmi:type="ecore:EAttribute" href="src/main/resources/model/problem.ecore#//ReferenceDeclaration/kind"/>
+        <semanticElements xmi:type="ecore:EAttribute" href="src/main/resources/model/problem.ecore#//ReferenceDeclaration/kind"/>
+        <ownedStyle xmi:type="diagram:BundledImage" uid="__BoC8jNlEe2fD4dIhR_vzA" labelAlignment="LEFT">
           <description xmi:type="style:BundledImageDescription" href="platform:/plugin/org.eclipse.emf.ecoretools.design/description/ecore.odesign#//@ownedViewpoints[name='Design']/@ownedRepresentations[name='Entities']/@defaultLayer/@containerMappings[name='EC%20EClass']/@subNodeMappings[name='EC%20EAttribute']/@style"/>
         </ownedStyle>
         <actualMapping xmi:type="description_1:NodeMapping" href="platform:/plugin/org.eclipse.emf.ecoretools.design/description/ecore.odesign#//@ownedViewpoints[name='Design']/@ownedRepresentations[name='Entities']/@defaultLayer/@containerMappings[name='EC%20EClass']/@subNodeMappings[name='EC%20EAttribute']"/>
@@ -1959,12 +2009,12 @@
     <ownedDiagramElements xmi:type="diagram:DEdge" uid="_gRoBcKA4EeuqkpDnuik1sg" sourceNode="_c-A7oKA4EeuqkpDnuik1sg" targetNode="_EfNqcKA4EeuqkpDnuik1sg">
       <target xmi:type="ecore:EClass" href="src/main/resources/model/problem.ecore#//ReferenceDeclaration"/>
       <semanticElements xmi:type="ecore:EClass" href="src/main/resources/model/problem.ecore#//ReferenceDeclaration"/>
-      <ownedStyle xmi:type="diagram:EdgeStyle" uid="_IMsMUKA5EeuqkpDnuik1sg" targetArrow="InputClosedArrow" routingStyle="tree">
+      <ownedStyle xmi:type="diagram:EdgeStyle" uid="__Bwl6DNlEe2fD4dIhR_vzA" targetArrow="InputClosedArrow" routingStyle="tree">
         <description xmi:type="style:EdgeStyleDescription" href="platform:/plugin/org.eclipse.emf.ecoretools.design/description/ecore.odesign#//@ownedViewpoints[name='Design']/@ownedRepresentations[name='Entities']/@defaultLayer/@edgeMappings[name='EC%20ESupertypes']/@style"/>
-        <beginLabelStyle xmi:type="diagram:BeginLabelStyle" uid="_IMsMUaA5EeuqkpDnuik1sg" showIcon="false">
+        <beginLabelStyle xmi:type="diagram:BeginLabelStyle" uid="__Bwl6TNlEe2fD4dIhR_vzA" showIcon="false">
           <labelFormat>italic</labelFormat>
         </beginLabelStyle>
-        <centerLabelStyle xmi:type="diagram:CenterLabelStyle" uid="_IMsMUqA5EeuqkpDnuik1sg" showIcon="false"/>
+        <centerLabelStyle xmi:type="diagram:CenterLabelStyle" uid="__Bwl6jNlEe2fD4dIhR_vzA" showIcon="false"/>
       </ownedStyle>
       <actualMapping xmi:type="description_1:EdgeMapping" href="platform:/plugin/org.eclipse.emf.ecoretools.design/description/ecore.odesign#//@ownedViewpoints[name='Design']/@ownedRepresentations[name='Entities']/@defaultLayer/@edgeMappings[name='EC%20ESupertypes']"/>
     </ownedDiagramElements>
@@ -2047,14 +2097,14 @@
       <arrangeConstraints>KEEP_LOCATION</arrangeConstraints>
       <arrangeConstraints>KEEP_SIZE</arrangeConstraints>
       <arrangeConstraints>KEEP_RATIO</arrangeConstraints>
-      <ownedStyle xmi:type="diagram:FlatContainerStyle" uid="_OHh2exEJEe2AArBmfNpEZA" borderSize="1" borderSizeComputationExpression="1" backgroundStyle="Liquid" foregroundColor="255,252,216">
+      <ownedStyle xmi:type="diagram:FlatContainerStyle" uid="_jX0uAjNoEe2fD4dIhR_vzA" borderSize="1" borderSizeComputationExpression="1" backgroundStyle="Liquid" foregroundColor="255,252,216">
         <description xmi:type="style:FlatContainerStyleDescription" href="platform:/plugin/org.eclipse.emf.ecoretools.design/description/ecore.odesign#//@ownedViewpoints[name='Design']/@ownedRepresentations[name='Entities']/@defaultLayer/@containerMappings[name='EC%20EClass']/@style"/>
       </ownedStyle>
       <actualMapping xmi:type="description_1:ContainerMapping" href="platform:/plugin/org.eclipse.emf.ecoretools.design/description/ecore.odesign#//@ownedViewpoints[name='Design']/@ownedRepresentations[name='Entities']/@defaultLayer/@containerMappings[name='EC%20EClass']"/>
-      <ownedElements xmi:type="diagram:DNodeListElement" uid="_svs2QKA5EeuqkpDnuik1sg" name="error : EBoolean = false" tooltipText="">
-        <target xmi:type="ecore:EAttribute" href="src/main/resources/model/problem.ecore#//PredicateDefinition/error"/>
-        <semanticElements xmi:type="ecore:EAttribute" href="src/main/resources/model/problem.ecore#//PredicateDefinition/error"/>
-        <ownedStyle xmi:type="diagram:BundledImage" uid="_tWLAYaA5EeuqkpDnuik1sg" labelAlignment="LEFT">
+      <ownedElements xmi:type="diagram:DNodeListElement" uid="_ida7QDNoEe2fD4dIhR_vzA" name="kind : PredicateKind = DEFAULT" tooltipText="">
+        <target xmi:type="ecore:EAttribute" href="src/main/resources/model/problem.ecore#//PredicateDefinition/kind"/>
+        <semanticElements xmi:type="ecore:EAttribute" href="src/main/resources/model/problem.ecore#//PredicateDefinition/kind"/>
+        <ownedStyle xmi:type="diagram:BundledImage" uid="_jX18JDNoEe2fD4dIhR_vzA" labelAlignment="LEFT">
           <description xmi:type="style:BundledImageDescription" href="platform:/plugin/org.eclipse.emf.ecoretools.design/description/ecore.odesign#//@ownedViewpoints[name='Design']/@ownedRepresentations[name='Entities']/@defaultLayer/@containerMappings[name='EC%20EClass']/@subNodeMappings[name='EC%20EAttribute']/@style"/>
         </ownedStyle>
         <actualMapping xmi:type="description_1:NodeMapping" href="platform:/plugin/org.eclipse.emf.ecoretools.design/description/ecore.odesign#//@ownedViewpoints[name='Design']/@ownedRepresentations[name='Entities']/@defaultLayer/@containerMappings[name='EC%20EClass']/@subNodeMappings[name='EC%20EAttribute']"/>
@@ -2063,12 +2113,12 @@
     <ownedDiagramElements xmi:type="diagram:DEdge" uid="_rUgDkKA5EeuqkpDnuik1sg" sourceNode="_fihqUKA5EeuqkpDnuik1sg" targetNode="_EfNqcKA4EeuqkpDnuik1sg">
       <target xmi:type="ecore:EClass" href="src/main/resources/model/problem.ecore#//PredicateDefinition"/>
       <semanticElements xmi:type="ecore:EClass" href="src/main/resources/model/problem.ecore#//PredicateDefinition"/>
-      <ownedStyle xmi:type="diagram:EdgeStyle" uid="_OHuDzhEJEe2AArBmfNpEZA" targetArrow="InputClosedArrow" routingStyle="tree">
+      <ownedStyle xmi:type="diagram:EdgeStyle" uid="_jX7bzjNoEe2fD4dIhR_vzA" targetArrow="InputClosedArrow" routingStyle="tree">
         <description xmi:type="style:EdgeStyleDescription" href="platform:/plugin/org.eclipse.emf.ecoretools.design/description/ecore.odesign#//@ownedViewpoints[name='Design']/@ownedRepresentations[name='Entities']/@defaultLayer/@edgeMappings[name='EC%20ESupertypes']/@style"/>
-        <beginLabelStyle xmi:type="diagram:BeginLabelStyle" uid="_OHuDzxEJEe2AArBmfNpEZA" showIcon="false">
+        <beginLabelStyle xmi:type="diagram:BeginLabelStyle" uid="_jX7bzzNoEe2fD4dIhR_vzA" showIcon="false">
           <labelFormat>italic</labelFormat>
         </beginLabelStyle>
-        <centerLabelStyle xmi:type="diagram:CenterLabelStyle" uid="_OHuD0BEJEe2AArBmfNpEZA" showIcon="false"/>
+        <centerLabelStyle xmi:type="diagram:CenterLabelStyle" uid="_jX7b0DNoEe2fD4dIhR_vzA" showIcon="false"/>
       </ownedStyle>
       <actualMapping xmi:type="description_1:EdgeMapping" href="platform:/plugin/org.eclipse.emf.ecoretools.design/description/ecore.odesign#//@ownedViewpoints[name='Design']/@ownedRepresentations[name='Entities']/@defaultLayer/@edgeMappings[name='EC%20ESupertypes']"/>
     </ownedDiagramElements>
@@ -2551,7 +2601,7 @@
         <actualMapping xmi:type="description_1:NodeMapping" href="platform:/plugin/org.eclipse.emf.ecoretools.design/description/ecore.odesign#//@ownedViewpoints[name='Design']/@ownedRepresentations[name='Entities']/@defaultLayer/@containerMappings[name='EC%20EClass']/@subNodeMappings[name='EC%20EAttribute']"/>
       </ownedElements>
     </ownedDiagramElements>
-    <ownedDiagramElements xmi:type="diagram:DEdge" uid="_2kWqbKA9EeuqkpDnuik1sg" name="[0..1] targetType" sourceNode="_zac6MKA9EeuqkpDnuik1sg" targetNode="_JTstIKA4EeuqkpDnuik1sg">
+    <ownedDiagramElements xmi:type="diagram:DEdge" uid="_2kWqbKA9EeuqkpDnuik1sg" name="[0..1] targetType" sourceNode="_zac6MKA9EeuqkpDnuik1sg" targetNode="_EfNqcKA4EeuqkpDnuik1sg">
       <target xmi:type="ecore:EReference" href="src/main/resources/model/problem.ecore#//TypeScope/targetType"/>
       <semanticElements xmi:type="ecore:EReference" href="src/main/resources/model/problem.ecore#//TypeScope/targetType"/>
       <ownedStyle xmi:type="diagram:EdgeStyle" uid="_2kXRcKA9EeuqkpDnuik1sg" routingStyle="manhattan" strokeColor="0,0,0">
@@ -3288,12 +3338,12 @@
     <ownedDiagramElements xmi:type="diagram:DEdge" uid="_ddmjcCrZEeyyC-O0_LlY9w" sourceNode="_fihqUKA5EeuqkpDnuik1sg" targetNode="_A8hIkCrZEeyyC-O0_LlY9w">
       <target xmi:type="ecore:EClass" href="src/main/resources/model/problem.ecore#//PredicateDefinition"/>
       <semanticElements xmi:type="ecore:EClass" href="src/main/resources/model/problem.ecore#//PredicateDefinition"/>
-      <ownedStyle xmi:type="diagram:EdgeStyle" uid="_OHuD1BEJEe2AArBmfNpEZA" lineStyle="dash" targetArrow="InputClosedArrow" routingStyle="tree">
+      <ownedStyle xmi:type="diagram:EdgeStyle" uid="_jX7b1DNoEe2fD4dIhR_vzA" lineStyle="dash" targetArrow="InputClosedArrow" routingStyle="tree">
         <description xmi:type="style:EdgeStyleDescription" href="platform:/plugin/org.eclipse.emf.ecoretools.design/description/ecore.odesign#//@ownedViewpoints[name='Design']/@ownedRepresentations[name='Entities']/@defaultLayer/@edgeMappings[name='EC%20ESupertypes']/@conditionnalStyles.0/@style"/>
-        <beginLabelStyle xmi:type="diagram:BeginLabelStyle" uid="_OHuD1REJEe2AArBmfNpEZA" showIcon="false">
+        <beginLabelStyle xmi:type="diagram:BeginLabelStyle" uid="_jX7b1TNoEe2fD4dIhR_vzA" showIcon="false">
           <labelFormat>italic</labelFormat>
         </beginLabelStyle>
-        <centerLabelStyle xmi:type="diagram:CenterLabelStyle" uid="_OHuD1hEJEe2AArBmfNpEZA" showIcon="false"/>
+        <centerLabelStyle xmi:type="diagram:CenterLabelStyle" uid="_jX7b1jNoEe2fD4dIhR_vzA" showIcon="false"/>
       </ownedStyle>
       <actualMapping xmi:type="description_1:EdgeMapping" href="platform:/plugin/org.eclipse.emf.ecoretools.design/description/ecore.odesign#//@ownedViewpoints[name='Design']/@ownedRepresentations[name='Entities']/@defaultLayer/@edgeMappings[name='EC%20ESupertypes']"/>
     </ownedDiagramElements>
@@ -3689,6 +3739,92 @@
         <actualMapping xmi:type="description_1:NodeMapping" href="platform:/plugin/org.eclipse.emf.ecoretools.design/description/ecore.odesign#//@ownedViewpoints[name='Design']/@ownedRepresentations[name='Entities']/@defaultLayer/@containerMappings[name='EC%20EEnum']/@subNodeMappings[name='EC%20EEnumLiteral']"/>
       </ownedElements>
     </ownedDiagramElements>
+    <ownedDiagramElements xmi:type="diagram:DNodeList" uid="_xpDfUDNlEe2fD4dIhR_vzA" name="ReferenceKind" tooltipText="" width="12" height="10">
+      <target xmi:type="ecore:EEnum" href="src/main/resources/model/problem.ecore#//ReferenceKind"/>
+      <semanticElements xmi:type="ecore:EEnum" href="src/main/resources/model/problem.ecore#//ReferenceKind"/>
+      <arrangeConstraints>KEEP_LOCATION</arrangeConstraints>
+      <arrangeConstraints>KEEP_SIZE</arrangeConstraints>
+      <arrangeConstraints>KEEP_RATIO</arrangeConstraints>
+      <ownedStyle xmi:type="diagram:FlatContainerStyle" uid="_xpDfUTNlEe2fD4dIhR_vzA" borderSize="1" borderSizeComputationExpression="1" borderColor="125,125,125" backgroundStyle="Liquid" foregroundColor="221,236,202">
+        <description xmi:type="style:FlatContainerStyleDescription" href="platform:/plugin/org.eclipse.emf.ecoretools.design/description/ecore.odesign#//@ownedViewpoints[name='Design']/@ownedRepresentations[name='Entities']/@defaultLayer/@containerMappings[name='EC%20EEnum']/@style"/>
+      </ownedStyle>
+      <actualMapping xmi:type="description_1:ContainerMapping" href="platform:/plugin/org.eclipse.emf.ecoretools.design/description/ecore.odesign#//@ownedViewpoints[name='Design']/@ownedRepresentations[name='Entities']/@defaultLayer/@containerMappings[name='EC%20EEnum']"/>
+      <ownedElements xmi:type="diagram:DNodeListElement" uid="_2N3HQDNlEe2fD4dIhR_vzA" name="DEFAULT" tooltipText="">
+        <target xmi:type="ecore:EEnumLiteral" href="src/main/resources/model/problem.ecore#//ReferenceKind/DEFAULT"/>
+        <semanticElements xmi:type="ecore:EEnumLiteral" href="src/main/resources/model/problem.ecore#//ReferenceKind/DEFAULT"/>
+        <ownedStyle xmi:type="diagram:BundledImage" uid="_2N3HQTNlEe2fD4dIhR_vzA" labelAlignment="LEFT">
+          <description xmi:type="style:BundledImageDescription" href="platform:/plugin/org.eclipse.emf.ecoretools.design/description/ecore.odesign#//@ownedViewpoints[name='Design']/@ownedRepresentations[name='Entities']/@defaultLayer/@containerMappings[name='EC%20EEnum']/@subNodeMappings[name='EC%20EEnumLiteral']/@style"/>
+        </ownedStyle>
+        <actualMapping xmi:type="description_1:NodeMapping" href="platform:/plugin/org.eclipse.emf.ecoretools.design/description/ecore.odesign#//@ownedViewpoints[name='Design']/@ownedRepresentations[name='Entities']/@defaultLayer/@containerMappings[name='EC%20EEnum']/@subNodeMappings[name='EC%20EEnumLiteral']"/>
+      </ownedElements>
+      <ownedElements xmi:type="diagram:DNodeListElement" uid="_2zSIgDNlEe2fD4dIhR_vzA" name="REFERENCE" tooltipText="">
+        <target xmi:type="ecore:EEnumLiteral" href="src/main/resources/model/problem.ecore#//ReferenceKind/REFERENCE"/>
+        <semanticElements xmi:type="ecore:EEnumLiteral" href="src/main/resources/model/problem.ecore#//ReferenceKind/REFERENCE"/>
+        <ownedStyle xmi:type="diagram:BundledImage" uid="_2zSvkDNlEe2fD4dIhR_vzA" labelAlignment="LEFT">
+          <description xmi:type="style:BundledImageDescription" href="platform:/plugin/org.eclipse.emf.ecoretools.design/description/ecore.odesign#//@ownedViewpoints[name='Design']/@ownedRepresentations[name='Entities']/@defaultLayer/@containerMappings[name='EC%20EEnum']/@subNodeMappings[name='EC%20EEnumLiteral']/@style"/>
+        </ownedStyle>
+        <actualMapping xmi:type="description_1:NodeMapping" href="platform:/plugin/org.eclipse.emf.ecoretools.design/description/ecore.odesign#//@ownedViewpoints[name='Design']/@ownedRepresentations[name='Entities']/@defaultLayer/@containerMappings[name='EC%20EEnum']/@subNodeMappings[name='EC%20EEnumLiteral']"/>
+      </ownedElements>
+      <ownedElements xmi:type="diagram:DNodeListElement" uid="_4K8fADNlEe2fD4dIhR_vzA" name="CONTAINMENT" tooltipText="">
+        <target xmi:type="ecore:EEnumLiteral" href="src/main/resources/model/problem.ecore#//ReferenceKind/CONTAINMENT"/>
+        <semanticElements xmi:type="ecore:EEnumLiteral" href="src/main/resources/model/problem.ecore#//ReferenceKind/CONTAINMENT"/>
+        <ownedStyle xmi:type="diagram:BundledImage" uid="_4K8fATNlEe2fD4dIhR_vzA" labelAlignment="LEFT">
+          <description xmi:type="style:BundledImageDescription" href="platform:/plugin/org.eclipse.emf.ecoretools.design/description/ecore.odesign#//@ownedViewpoints[name='Design']/@ownedRepresentations[name='Entities']/@defaultLayer/@containerMappings[name='EC%20EEnum']/@subNodeMappings[name='EC%20EEnumLiteral']/@style"/>
+        </ownedStyle>
+        <actualMapping xmi:type="description_1:NodeMapping" href="platform:/plugin/org.eclipse.emf.ecoretools.design/description/ecore.odesign#//@ownedViewpoints[name='Design']/@ownedRepresentations[name='Entities']/@defaultLayer/@containerMappings[name='EC%20EEnum']/@subNodeMappings[name='EC%20EEnumLiteral']"/>
+      </ownedElements>
+      <ownedElements xmi:type="diagram:DNodeListElement" uid="_5MhQwDNlEe2fD4dIhR_vzA" name="CONTAINER" tooltipText="">
+        <target xmi:type="ecore:EEnumLiteral" href="src/main/resources/model/problem.ecore#//ReferenceKind/CONTAINER"/>
+        <semanticElements xmi:type="ecore:EEnumLiteral" href="src/main/resources/model/problem.ecore#//ReferenceKind/CONTAINER"/>
+        <ownedStyle xmi:type="diagram:BundledImage" uid="_5MhQwTNlEe2fD4dIhR_vzA" labelAlignment="LEFT">
+          <description xmi:type="style:BundledImageDescription" href="platform:/plugin/org.eclipse.emf.ecoretools.design/description/ecore.odesign#//@ownedViewpoints[name='Design']/@ownedRepresentations[name='Entities']/@defaultLayer/@containerMappings[name='EC%20EEnum']/@subNodeMappings[name='EC%20EEnumLiteral']/@style"/>
+        </ownedStyle>
+        <actualMapping xmi:type="description_1:NodeMapping" href="platform:/plugin/org.eclipse.emf.ecoretools.design/description/ecore.odesign#//@ownedViewpoints[name='Design']/@ownedRepresentations[name='Entities']/@defaultLayer/@containerMappings[name='EC%20EEnum']/@subNodeMappings[name='EC%20EEnumLiteral']"/>
+      </ownedElements>
+    </ownedDiagramElements>
+    <ownedDiagramElements xmi:type="diagram:DNodeList" uid="_DD1pQDNoEe2fD4dIhR_vzA" name="PredicateKind" tooltipText="" width="12" height="10">
+      <target xmi:type="ecore:EEnum" href="src/main/resources/model/problem.ecore#//PredicateKind"/>
+      <semanticElements xmi:type="ecore:EEnum" href="src/main/resources/model/problem.ecore#//PredicateKind"/>
+      <arrangeConstraints>KEEP_LOCATION</arrangeConstraints>
+      <arrangeConstraints>KEEP_SIZE</arrangeConstraints>
+      <arrangeConstraints>KEEP_RATIO</arrangeConstraints>
+      <ownedStyle xmi:type="diagram:FlatContainerStyle" uid="_DD1pQTNoEe2fD4dIhR_vzA" borderSize="1" borderSizeComputationExpression="1" borderColor="125,125,125" backgroundStyle="Liquid" foregroundColor="221,236,202">
+        <description xmi:type="style:FlatContainerStyleDescription" href="platform:/plugin/org.eclipse.emf.ecoretools.design/description/ecore.odesign#//@ownedViewpoints[name='Design']/@ownedRepresentations[name='Entities']/@defaultLayer/@containerMappings[name='EC%20EEnum']/@style"/>
+      </ownedStyle>
+      <actualMapping xmi:type="description_1:ContainerMapping" href="platform:/plugin/org.eclipse.emf.ecoretools.design/description/ecore.odesign#//@ownedViewpoints[name='Design']/@ownedRepresentations[name='Entities']/@defaultLayer/@containerMappings[name='EC%20EEnum']"/>
+      <ownedElements xmi:type="diagram:DNodeListElement" uid="_FDOuIDNoEe2fD4dIhR_vzA" name="DEFAULT" tooltipText="">
+        <target xmi:type="ecore:EEnumLiteral" href="src/main/resources/model/problem.ecore#//PredicateKind/DEFAULT"/>
+        <semanticElements xmi:type="ecore:EEnumLiteral" href="src/main/resources/model/problem.ecore#//PredicateKind/DEFAULT"/>
+        <ownedStyle xmi:type="diagram:BundledImage" uid="_FDPVMDNoEe2fD4dIhR_vzA" labelAlignment="LEFT">
+          <description xmi:type="style:BundledImageDescription" href="platform:/plugin/org.eclipse.emf.ecoretools.design/description/ecore.odesign#//@ownedViewpoints[name='Design']/@ownedRepresentations[name='Entities']/@defaultLayer/@containerMappings[name='EC%20EEnum']/@subNodeMappings[name='EC%20EEnumLiteral']/@style"/>
+        </ownedStyle>
+        <actualMapping xmi:type="description_1:NodeMapping" href="platform:/plugin/org.eclipse.emf.ecoretools.design/description/ecore.odesign#//@ownedViewpoints[name='Design']/@ownedRepresentations[name='Entities']/@defaultLayer/@containerMappings[name='EC%20EEnum']/@subNodeMappings[name='EC%20EEnumLiteral']"/>
+      </ownedElements>
+      <ownedElements xmi:type="diagram:DNodeListElement" uid="_F2glMDNoEe2fD4dIhR_vzA" name="ERROR" tooltipText="">
+        <target xmi:type="ecore:EEnumLiteral" href="src/main/resources/model/problem.ecore#//PredicateKind/ERROR"/>
+        <semanticElements xmi:type="ecore:EEnumLiteral" href="src/main/resources/model/problem.ecore#//PredicateKind/ERROR"/>
+        <ownedStyle xmi:type="diagram:BundledImage" uid="_F2hMQDNoEe2fD4dIhR_vzA" labelAlignment="LEFT">
+          <description xmi:type="style:BundledImageDescription" href="platform:/plugin/org.eclipse.emf.ecoretools.design/description/ecore.odesign#//@ownedViewpoints[name='Design']/@ownedRepresentations[name='Entities']/@defaultLayer/@containerMappings[name='EC%20EEnum']/@subNodeMappings[name='EC%20EEnumLiteral']/@style"/>
+        </ownedStyle>
+        <actualMapping xmi:type="description_1:NodeMapping" href="platform:/plugin/org.eclipse.emf.ecoretools.design/description/ecore.odesign#//@ownedViewpoints[name='Design']/@ownedRepresentations[name='Entities']/@defaultLayer/@containerMappings[name='EC%20EEnum']/@subNodeMappings[name='EC%20EEnumLiteral']"/>
+      </ownedElements>
+      <ownedElements xmi:type="diagram:DNodeListElement" uid="_GS7bcDNoEe2fD4dIhR_vzA" name="CONTAINED" tooltipText="">
+        <target xmi:type="ecore:EEnumLiteral" href="src/main/resources/model/problem.ecore#//PredicateKind/CONTAINED"/>
+        <semanticElements xmi:type="ecore:EEnumLiteral" href="src/main/resources/model/problem.ecore#//PredicateKind/CONTAINED"/>
+        <ownedStyle xmi:type="diagram:BundledImage" uid="_GS7bcTNoEe2fD4dIhR_vzA" labelAlignment="LEFT">
+          <description xmi:type="style:BundledImageDescription" href="platform:/plugin/org.eclipse.emf.ecoretools.design/description/ecore.odesign#//@ownedViewpoints[name='Design']/@ownedRepresentations[name='Entities']/@defaultLayer/@containerMappings[name='EC%20EEnum']/@subNodeMappings[name='EC%20EEnumLiteral']/@style"/>
+        </ownedStyle>
+        <actualMapping xmi:type="description_1:NodeMapping" href="platform:/plugin/org.eclipse.emf.ecoretools.design/description/ecore.odesign#//@ownedViewpoints[name='Design']/@ownedRepresentations[name='Entities']/@defaultLayer/@containerMappings[name='EC%20EEnum']/@subNodeMappings[name='EC%20EEnumLiteral']"/>
+      </ownedElements>
+      <ownedElements xmi:type="diagram:DNodeListElement" uid="_Gx7EkDNoEe2fD4dIhR_vzA" name="CONTAINMENT" tooltipText="">
+        <target xmi:type="ecore:EEnumLiteral" href="src/main/resources/model/problem.ecore#//PredicateKind/CONTAINMENT"/>
+        <semanticElements xmi:type="ecore:EEnumLiteral" href="src/main/resources/model/problem.ecore#//PredicateKind/CONTAINMENT"/>
+        <ownedStyle xmi:type="diagram:BundledImage" uid="_Gx7roDNoEe2fD4dIhR_vzA" labelAlignment="LEFT">
+          <description xmi:type="style:BundledImageDescription" href="platform:/plugin/org.eclipse.emf.ecoretools.design/description/ecore.odesign#//@ownedViewpoints[name='Design']/@ownedRepresentations[name='Entities']/@defaultLayer/@containerMappings[name='EC%20EEnum']/@subNodeMappings[name='EC%20EEnumLiteral']/@style"/>
+        </ownedStyle>
+        <actualMapping xmi:type="description_1:NodeMapping" href="platform:/plugin/org.eclipse.emf.ecoretools.design/description/ecore.odesign#//@ownedViewpoints[name='Design']/@ownedRepresentations[name='Entities']/@defaultLayer/@containerMappings[name='EC%20EEnum']/@subNodeMappings[name='EC%20EEnumLiteral']"/>
+      </ownedElements>
+    </ownedDiagramElements>
     <description xmi:type="description_1:DiagramDescription" href="platform:/plugin/org.eclipse.emf.ecoretools.design/description/ecore.odesign#//@ownedViewpoints[name='Design']/@ownedRepresentations[name='Entities']"/>
     <filterVariableHistory xmi:type="diagram:FilterVariableHistory" uid="_CsWlsKA4EeuqkpDnuik1sg"/>
     <activatedLayers xmi:type="description_1:Layer" href="platform:/plugin/org.eclipse.emf.ecoretools.design/description/ecore.odesign#//@ownedViewpoints[name='Design']/@ownedRepresentations[name='Entities']/@defaultLayer"/>
diff --git a/subprojects/language-model/src/main/resources/model/problem.ecore b/subprojects/language-model/src/main/resources/model/problem.ecore
index 571d52f3..58f26eae 100644
--- a/subprojects/language-model/src/main/resources/model/problem.ecore
+++ b/subprojects/language-model/src/main/resources/model/problem.ecore
@@ -20,15 +20,15 @@
   <eClassifiers xsi:type="ecore:EClass" name="ReferenceDeclaration" eSuperTypes="#//Relation">
     <eStructuralFeatures xsi:type="ecore:EReference" name="referenceType" eType="#//Relation"/>
     <eStructuralFeatures xsi:type="ecore:EReference" name="opposite" eType="#//ReferenceDeclaration"/>
-    <eStructuralFeatures xsi:type="ecore:EAttribute" name="containment" eType="ecore:EDataType http://www.eclipse.org/emf/2002/Ecore#//EBoolean"/>
     <eStructuralFeatures xsi:type="ecore:EReference" name="multiplicity" eType="#//Multiplicity"
         containment="true"/>
+    <eStructuralFeatures xsi:type="ecore:EAttribute" name="kind" eType="#//ReferenceKind"/>
   </eClassifiers>
   <eClassifiers xsi:type="ecore:EClass" name="NamedElement" abstract="true">
     <eStructuralFeatures xsi:type="ecore:EAttribute" name="name" eType="ecore:EDataType http://www.eclipse.org/emf/2002/Ecore#//EString"/>
   </eClassifiers>
   <eClassifiers xsi:type="ecore:EClass" name="PredicateDefinition" eSuperTypes="#//Relation #//ParametricDefinition">
-    <eStructuralFeatures xsi:type="ecore:EAttribute" name="error" eType="ecore:EDataType http://www.eclipse.org/emf/2002/Ecore#//EBoolean"/>
+    <eStructuralFeatures xsi:type="ecore:EAttribute" name="kind" eType="#//PredicateKind"/>
   </eClassifiers>
   <eClassifiers xsi:type="ecore:EClass" name="Parameter" eSuperTypes="#//Variable">
     <eStructuralFeatures xsi:type="ecore:EReference" name="parameterType" eType="#//Relation"/>
@@ -78,7 +78,7 @@
   </eClassifiers>
   <eClassifiers xsi:type="ecore:EClass" name="Statement" abstract="true" interface="true"/>
   <eClassifiers xsi:type="ecore:EClass" name="TypeScope">
-    <eStructuralFeatures xsi:type="ecore:EReference" name="targetType" eType="#//ClassDeclaration"/>
+    <eStructuralFeatures xsi:type="ecore:EReference" name="targetType" eType="#//Relation"/>
     <eStructuralFeatures xsi:type="ecore:EAttribute" name="increment" eType="ecore:EDataType http://www.eclipse.org/emf/2002/Ecore#//EBoolean"/>
     <eStructuralFeatures xsi:type="ecore:EReference" name="multiplicity" eType="#//Multiplicity"
         containment="true"/>
@@ -191,4 +191,16 @@
     <eLiterals name="GREATER_EQ" value="3"/>
     <eLiterals name="EQ" value="4"/>
   </eClassifiers>
+  <eClassifiers xsi:type="ecore:EEnum" name="ReferenceKind">
+    <eLiterals name="DEFAULT"/>
+    <eLiterals name="REFERENCE" value="1"/>
+    <eLiterals name="CONTAINMENT" value="2"/>
+    <eLiterals name="CONTAINER" value="3"/>
+  </eClassifiers>
+  <eClassifiers xsi:type="ecore:EEnum" name="PredicateKind">
+    <eLiterals name="DEFAULT"/>
+    <eLiterals name="ERROR" value="1"/>
+    <eLiterals name="CONTAINED" value="2"/>
+    <eLiterals name="CONTAINMENT" value="3"/>
+  </eClassifiers>
 </ecore:EPackage>
diff --git a/subprojects/language-model/src/main/resources/model/problem.genmodel b/subprojects/language-model/src/main/resources/model/problem.genmodel
index 1b72ecfd..5442d29d 100644
--- a/subprojects/language-model/src/main/resources/model/problem.genmodel
+++ b/subprojects/language-model/src/main/resources/model/problem.genmodel
@@ -29,6 +29,18 @@
       <genEnumLiterals ecoreEnumLiteral="problem.ecore#//ComparisonOp/GREATER_EQ"/>
       <genEnumLiterals ecoreEnumLiteral="problem.ecore#//ComparisonOp/EQ"/>
     </genEnums>
+    <genEnums typeSafeEnumCompatible="false" ecoreEnum="problem.ecore#//ReferenceKind">
+      <genEnumLiterals ecoreEnumLiteral="problem.ecore#//ReferenceKind/DEFAULT"/>
+      <genEnumLiterals ecoreEnumLiteral="problem.ecore#//ReferenceKind/REFERENCE"/>
+      <genEnumLiterals ecoreEnumLiteral="problem.ecore#//ReferenceKind/CONTAINMENT"/>
+      <genEnumLiterals ecoreEnumLiteral="problem.ecore#//ReferenceKind/CONTAINER"/>
+    </genEnums>
+    <genEnums typeSafeEnumCompatible="false" ecoreEnum="problem.ecore#//PredicateKind">
+      <genEnumLiterals ecoreEnumLiteral="problem.ecore#//PredicateKind/DEFAULT"/>
+      <genEnumLiterals ecoreEnumLiteral="problem.ecore#//PredicateKind/ERROR"/>
+      <genEnumLiterals ecoreEnumLiteral="problem.ecore#//PredicateKind/CONTAINED"/>
+      <genEnumLiterals ecoreEnumLiteral="problem.ecore#//PredicateKind/CONTAINMENT"/>
+    </genEnums>
     <genClasses ecoreClass="problem.ecore#//Problem">
       <genFeatures property="None" children="true" createChild="true" ecoreFeature="ecore:EReference problem.ecore#//Problem/nodes"/>
       <genFeatures property="None" children="true" createChild="true" ecoreFeature="ecore:EReference problem.ecore#//Problem/statements"/>
@@ -43,14 +55,14 @@
     <genClasses ecoreClass="problem.ecore#//ReferenceDeclaration">
       <genFeatures notify="false" createChild="false" propertySortChoices="true" ecoreFeature="ecore:EReference problem.ecore#//ReferenceDeclaration/referenceType"/>
       <genFeatures notify="false" createChild="false" propertySortChoices="true" ecoreFeature="ecore:EReference problem.ecore#//ReferenceDeclaration/opposite"/>
-      <genFeatures createChild="false" ecoreFeature="ecore:EAttribute problem.ecore#//ReferenceDeclaration/containment"/>
       <genFeatures property="None" children="true" createChild="true" ecoreFeature="ecore:EReference problem.ecore#//ReferenceDeclaration/multiplicity"/>
+      <genFeatures createChild="false" ecoreFeature="ecore:EAttribute problem.ecore#//ReferenceDeclaration/kind"/>
     </genClasses>
     <genClasses ecoreClass="problem.ecore#//NamedElement">
       <genFeatures createChild="false" ecoreFeature="ecore:EAttribute problem.ecore#//NamedElement/name"/>
     </genClasses>
     <genClasses ecoreClass="problem.ecore#//PredicateDefinition">
-      <genFeatures createChild="false" ecoreFeature="ecore:EAttribute problem.ecore#//PredicateDefinition/error"/>
+      <genFeatures createChild="false" ecoreFeature="ecore:EAttribute problem.ecore#//PredicateDefinition/kind"/>
     </genClasses>
     <genClasses ecoreClass="problem.ecore#//Parameter">
       <genFeatures notify="false" createChild="false" propertySortChoices="true" ecoreFeature="ecore:EReference problem.ecore#//Parameter/parameterType"/>
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 f7b86dca..2a5af628 100644
--- a/subprojects/language/src/main/java/tools/refinery/language/Problem.xtext
+++ b/subprojects/language/src/main/java/tools/refinery/language/Problem.xtext
@@ -26,15 +26,23 @@ EnumDeclaration:
 EnumLiteral returns Node:
         name=Identifier;
 
+enum ReferenceKind:
+        REFERENCE="refers" | CONTAINMENT="contains" | CONTAINER="container";
+
 ReferenceDeclaration:
-        (containment?="contains" | "refers")?
-        referenceType=[Relation|QualifiedName]
+        (
+                kind=ReferenceKind referenceType=[Relation|QualifiedName] |
+                referenceType=[Relation|NonRelationKindQualifiedName]
+        )
         ("[" multiplicity=Multiplicity "]")?
         name=Identifier
         ("opposite" opposite=[ReferenceDeclaration|QualifiedName])?;
 
+enum PredicateKind:
+        ERROR="error" | CONTAINED="contained" | CONTAINMENT="containment";
+
 PredicateDefinition:
-        (error?="error" "pred"? | "pred")
+        (kind=PredicateKind "pred"? | "pred")
         name=Identifier
         "(" (parameters+=Parameter ("," parameters+=Parameter)*)? ")"
         ("<->" bodies+=Conjunction (";" bodies+=Conjunction)*)?
@@ -150,7 +158,7 @@ ScopeDeclaration:
         "scope" typeScopes+=TypeScope ("," typeScopes+=TypeScope)* ".";
 
 TypeScope:
-        targetType=[ClassDeclaration|QualifiedName]
+        targetType=[Relation|QualifiedName]
         (increment?="+=" | "=")
         multiplicity=DefiniteMultiplicity;
 
@@ -175,12 +183,19 @@ IndividualDeclaration:
 UpperBound returns ecore::EInt:
         INT | "*";
 
+NonRelationKindQualifiedName hidden():
+        NonRelationKindIdentifier ("::" Identifier)*;
+
 QualifiedName hidden():
         Identifier ("::" Identifier)*;
 
+NonRelationKindIdentifier:
+        ID | "true" | "false" | "unknown" | "error" | "class" | "abstract" | "extends" | "enum" |
+        "pred" | "indiv" | "problem" | "new" | "delete" | "rule" | "may" | "must" | "current" |
+        "count" | "default" | "scope" | "contained" | "containment";
+
 Identifier:
-        ID | "true" | "false" | "unknown" | "error" | "class" | "abstract" | "extends" | "enum" | "pred" |
-        "indiv" | "problem" | "new" | "delete" | "rule" | "may" | "must" | "current" | "count";
+        NonRelationKindIdentifier | "refers" | "contains" | "container";
 
 Integer returns ecore::EInt hidden():
         "-"? INT;
diff --git a/subprojects/language/src/main/java/tools/refinery/language/ProblemUtil.java b/subprojects/language/src/main/java/tools/refinery/language/ProblemUtil.java
index b1e39176..0be296fd 100644
--- a/subprojects/language/src/main/java/tools/refinery/language/ProblemUtil.java
+++ b/subprojects/language/src/main/java/tools/refinery/language/ProblemUtil.java
@@ -27,6 +27,10 @@ public final class ProblemUtil {
 
         public static final String NODE_CLASS_NAME = "node";
 
+        public static final String DOMAIN_CLASS_NAME = "domain";
+
+        public static final String DATA_CLASS_NAME = "data";
+
         private ProblemUtil() {
                 throw new IllegalStateException("This is a static utility class and should not be instantiated directly");
         }
@@ -80,15 +84,15 @@ public final class ProblemUtil {
                 return false;
         }
 
-        public static Optional<ClassDeclaration> getNodeClassDeclaration(EObject context) {
+        public static Optional<ClassDeclaration> getBuiltinClassDeclaration(EObject context, String name) {
                 return getBuiltInLibrary(context).flatMap(problem -> problem.getStatements().stream()
                                 .filter(ClassDeclaration.class::isInstance).map(ClassDeclaration.class::cast)
-                                .filter(declaration -> NODE_CLASS_NAME.equals(declaration.getName())).findFirst());
+                                .filter(declaration -> name.equals(declaration.getName())).findFirst());
         }
 
         public static Collection<ClassDeclaration> getSuperclassesAndSelf(ClassDeclaration classDeclaration) {
                 Set<ClassDeclaration> found = new HashSet<>();
-                getNodeClassDeclaration(classDeclaration).ifPresent(found::add);
+                getBuiltinClassDeclaration(classDeclaration, NODE_CLASS_NAME).ifPresent(found::add);
                 Deque<ClassDeclaration> queue = new ArrayDeque<>();
                 queue.addLast(classDeclaration);
                 while (!queue.isEmpty()) {
@@ -102,6 +106,11 @@ public final class ProblemUtil {
                                 }
                         }
                 }
+                getBuiltinClassDeclaration(classDeclaration, DATA_CLASS_NAME).ifPresent((dataClassDelcaration) -> {
+                        if (!found.contains(dataClassDelcaration)) {
+                                getBuiltinClassDeclaration(classDeclaration, DOMAIN_CLASS_NAME).ifPresent(found::add);
+                        }
+                });
                 return found;
         }
 
@@ -113,6 +122,28 @@ public final class ProblemUtil {
                 return referenceDeclarations;
         }
 
+        public static boolean isDataClass(Relation relation) {
+                if (relation instanceof ClassDeclaration classDeclaration) {
+                        var supertypes = getSuperclassesAndSelf(classDeclaration);
+                        return getBuiltinClassDeclaration(classDeclaration, DATA_CLASS_NAME).map(supertypes::contains)
+                                        .orElse(false);
+                }
+                return false;
+        }
+
+        public static boolean isContainmentReference(ReferenceDeclaration referenceDeclaration) {
+                switch (referenceDeclaration.getKind()) {
+                case REFERENCE, CONTAINER:
+                        return false;
+                case CONTAINMENT:
+                        return true;
+                case DEFAULT:
+                        return isDataClass(referenceDeclaration.getReferenceType());
+                default:
+                        throw new IllegalArgumentException("Unknown reference kind " + referenceDeclaration.getKind());
+                }
+        }
+
         private static URI getLibraryUri(String libraryName) {
                 return URI.createURI(ProblemUtil.class.getClassLoader()
                                 .getResource("tools/refinery/language/%s.problem".formatted(libraryName)).toString());
diff --git a/subprojects/language/src/main/resources/tools/refinery/language/builtin.problem b/subprojects/language/src/main/resources/tools/refinery/language/builtin.problem
index 323e03f1..e39ff1a3 100644
--- a/subprojects/language/src/main/resources/tools/refinery/language/builtin.problem
+++ b/subprojects/language/src/main/resources/tools/refinery/language/builtin.problem
@@ -19,3 +19,22 @@ class real extends data.
 class int extends data.
 
 class string extends data.
+
+pred contained(node node).
+
+pred contains(node container, node contained).
+
+pred root(node node).
+
+% error missingContainer(contained node) <->
+%     !contains(node, _), !root(node).
+%
+% error tooManyContainers(contained node) <->
+%     count contains(_, node) > 1
+% ;
+%     contains(_, node), root(node)
+% ;
+%         contains(_, node), !contained(node).
+%
+% error containmentCycle(node node) <->
+%     contains+(node, node).