diff --git a/src/main/java/fr/inria/corese/core/next/query/impl/sparql/bridge/CoreseAstQueryBuilder.java b/src/main/java/fr/inria/corese/core/next/query/impl/sparql/bridge/CoreseAstQueryBuilder.java
index 808664e35..e5c6641a1 100644
--- a/src/main/java/fr/inria/corese/core/next/query/impl/sparql/bridge/CoreseAstQueryBuilder.java
+++ b/src/main/java/fr/inria/corese/core/next/query/impl/sparql/bridge/CoreseAstQueryBuilder.java
@@ -1,9 +1,9 @@
 package fr.inria.corese.core.next.query.impl.sparql.bridge;
 
-import fr.inria.corese.core.next.query.impl.sparql.ast.ConstraintAst;
-import fr.inria.corese.core.next.query.impl.sparql.ast.FilterAst;
-import fr.inria.corese.core.next.query.impl.sparql.ast.TermAst;
+import fr.inria.corese.core.next.query.impl.sparql.ast.*;
 import fr.inria.corese.core.next.query.kgram.api.core.Filter;
+import fr.inria.corese.core.next.query.kgram.core.Exp;
+import fr.inria.corese.core.next.query.kgram.core.Query;
 
 import java.util.Objects;
 
@@ -15,6 +15,40 @@ public final class CoreseAstQueryBuilder {
     public CoreseAstQueryBuilder() {
     }
 
+    private final WhereCompiler whereCompiler = new WhereCompiler();
+
+    /**
+     * Builds a KGRAM {@link Query} from a SPARQL {@code ASK} query AST.
+     */
+    public Query toQuery(AskQueryAst ask) {
+        Objects.requireNonNull(ask, "ask");
+        rejectUnsupportedClauses(ask);
+
+        Exp body = whereCompiler.compile(ask.whereClause());
+        Query query = Query.create(body);
+        query.setAsk(true);
+
+        return query;
+    }
+
+    private static void rejectUnsupportedClauses(AskQueryAst ask) {
+        DatasetClauseAst dataset = ask.datasetClause();
+        if (!dataset.graphs().isEmpty() || !dataset.namedGraphs().isEmpty()) {
+            throw new UnsupportedOperationException(
+                    "FROM / FROM NAMED is not supported yet for ASK (dataset handling is a follow-up)");
+        }
+        if (!ask.valuesClause().mappings().isEmpty()) {
+            throw new UnsupportedOperationException(
+                    "Inline VALUES is not supported yet for ASK (values handling is a follow-up)");
+        }
+        SolutionModifierAst mod = ask.solutionModifier();
+        if (mod.hasOrderBy() || mod.hasGroupBy() || mod.hasHaving()
+                || mod.hasLimit() || mod.hasOffset() || mod.distinct() || mod.reduced()) {
+            throw new UnsupportedOperationException(
+                    "Solution modifiers (ORDER BY, GROUP BY, HAVING, LIMIT, OFFSET, DISTINCT, REDUCED) are not supported for ASK");
+        }
+    }
+
     /**
      * Converts a SPARQL {@code FILTER} clause by converting {@link FilterAst#operator()} the same way as
      * {@link #toNextFilter(TermAst)}.
@@ -44,4 +78,4 @@ public Filter toNextFilter(ConstraintAst filterExpression) {
         return SparqlAstToExpression.toNextFilter(filterExpression);
     }
 
-}
+}
\ No newline at end of file
diff --git a/src/main/java/fr/inria/corese/core/next/query/impl/sparql/bridge/SparqlAstToExpression.java b/src/main/java/fr/inria/corese/core/next/query/impl/sparql/bridge/SparqlAstToExpression.java
index 91ed53006..b2c7aaf80 100644
--- a/src/main/java/fr/inria/corese/core/next/query/impl/sparql/bridge/SparqlAstToExpression.java
+++ b/src/main/java/fr/inria/corese/core/next/query/impl/sparql/bridge/SparqlAstToExpression.java
@@ -6,12 +6,9 @@
 import fr.inria.corese.core.next.query.kgram.api.core.Filter;
 import fr.inria.corese.core.next.util.StringUtils;
 import fr.inria.corese.core.sparql.datatype.RDF;
-import fr.inria.corese.core.sparql.triple.parser.Constant;
-import fr.inria.corese.core.sparql.triple.parser.Expression;
-import fr.inria.corese.core.sparql.triple.parser.Processor;
-import fr.inria.corese.core.sparql.triple.parser.Term;
-import fr.inria.corese.core.sparql.triple.parser.Variable;
+import fr.inria.corese.core.sparql.triple.parser.*;
 
+import java.util.ArrayList;
 import java.util.List;
 import java.util.Objects;
 import java.util.Optional;
@@ -60,10 +57,23 @@ public static Filter toNextFilter(FilterAst filterClause) {
      */
     public static Filter toNextFilter(TermAst filterExpression) {
         Expression exprTree = convert(filterExpression);
+        initializeExpList(exprTree);
         AstBackedExpr expr = new AstBackedExpr(exprTree, Optional.of(filterExpression));
         return expr.getFilter();
     }
 
+    /**
+     * Initializes the {@code Expr} list ({@code lExp}) of every {@link Term} in the tree.
+     */
+    private static void initializeExpList(Expression expression) {
+        if (expression instanceof Term term) {
+            for (Expression arg : term.getArgs()) {
+                initializeExpList(arg);
+            }
+            term.setExpList(new ArrayList<>(term.getArgs()));
+        }
+    }
+
     private static Constant literalToConstant(LiteralAst l) {
         if (l.lang() != null && !l.lang().isEmpty()) {
             return Constant.create(unquoteLexical(l.lexical()), RDF.rdflangString, l.lang());
diff --git a/src/main/java/fr/inria/corese/core/next/query/kgram/core/Query.java b/src/main/java/fr/inria/corese/core/next/query/kgram/core/Query.java
index f6d20b3cb..a10860ba8 100644
--- a/src/main/java/fr/inria/corese/core/next/query/kgram/core/Query.java
+++ b/src/main/java/fr/inria/corese/core/next/query/kgram/core/Query.java
@@ -139,6 +139,7 @@ public static DQPFactory getFactory() {
     private boolean isInsert = false;
     boolean isDelete = false;
     boolean isUpdate = false;
+    boolean isAsk = false;
     boolean isCheckLoop = false;
     boolean isListGroup = false;
     boolean isListPath = true;
@@ -685,6 +686,14 @@ public void setUpdate(boolean b) {
         isUpdate = b;
     }
 
+    public boolean isAsk() {
+        return isAsk;
+    }
+
+    public void setAsk(boolean b) {
+        isAsk = b;
+    }
+
     public boolean isTest() {
         return isTest;
     }
diff --git a/src/test/java/fr/inria/corese/core/next/query/impl/sparql/bridge/CoreseAstQueryBuilderAskTest.java b/src/test/java/fr/inria/corese/core/next/query/impl/sparql/bridge/CoreseAstQueryBuilderAskTest.java
new file mode 100644
index 000000000..1585b1040
--- /dev/null
+++ b/src/test/java/fr/inria/corese/core/next/query/impl/sparql/bridge/CoreseAstQueryBuilderAskTest.java
@@ -0,0 +1,114 @@
+package fr.inria.corese.core.next.query.impl.sparql.bridge;
+
+import fr.inria.corese.core.next.query.impl.sparql.ast.*;
+import fr.inria.corese.core.next.query.impl.sparql.ast.constraint.GreaterThanAst;
+import fr.inria.corese.core.next.query.kgram.core.Query;
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Test;
+
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+class CoreseAstQueryBuilderAskTest {
+
+    private final CoreseAstQueryBuilder builder = new CoreseAstQueryBuilder();
+
+    private static GroupGraphPatternAst whereOneTriple() {
+        return new GroupGraphPatternAst(List.of(
+                new BgpAst(List.of(
+                        new TriplePatternAst(new VarAst("s"), new VarAst("p"), new VarAst("o"))))));
+    }
+
+    @Test
+    @DisplayName("Query body is the compiled WHERE and the query is flagged as ASK")
+    void buildsBodyAndAskFlag() {
+        AskQueryAst ask = new AskQueryAst(DatasetClauseAst.none(), whereOneTriple());
+
+        Query query = builder.toQuery(ask);
+
+        assertNotNull(query.getBody(), "body set from WHERE");
+        assertTrue(query.getBody().isAnd(), "group compiles to AND");
+        assertTrue(query.getBody().get(0).isBGP(), "containing the BGP");
+        assertTrue(query.isAsk(), "query flagged as ASK");
+    }
+
+    @Test
+    @DisplayName("A FILTER in the WHERE no longer throws an NPE (lExp fix)")
+    void buildsAskWithFilter() {
+        FilterAst filter = new FilterAst(new GreaterThanAst(List.of(
+                new VarAst("o"), new LiteralAst("5", null, null))));
+        GroupGraphPatternAst where = new GroupGraphPatternAst(List.of(
+                new BgpAst(List.of(
+                        new TriplePatternAst(new VarAst("s"), new VarAst("p"), new VarAst("o")))),
+                filter));
+        AskQueryAst ask = new AskQueryAst(DatasetClauseAst.none(), where);
+
+        Query query = builder.toQuery(ask);
+
+        assertTrue(query.isAsk());
+        assertTrue(query.getBody().get(1).isFilter(), "FILTER compiled into the body");
+    }
+
+    @Test
+    @DisplayName("FROM is not supported yet → UnsupportedOperationException")
+    void rejectsFromClause() {
+        DatasetClauseAst dataset = new DatasetClauseAst(
+                Set.of(new IriAst("http://example.org/g")), Set.of());
+        AskQueryAst ask = new AskQueryAst(dataset, whereOneTriple());
+
+        assertThrows(UnsupportedOperationException.class, () -> builder.toQuery(ask));
+    }
+
+    @Test
+    @DisplayName("FROM NAMED is not supported yet → UnsupportedOperationException")
+    void rejectsFromNamedClause() {
+        DatasetClauseAst dataset = new DatasetClauseAst(
+                Set.of(), Set.of(new IriAst("http://example.org/g")));
+        AskQueryAst ask = new AskQueryAst(dataset, whereOneTriple());
+
+        assertThrows(UnsupportedOperationException.class, () -> builder.toQuery(ask));
+    }
+
+    @Test
+    @DisplayName("Inline VALUES is not supported yet → UnsupportedOperationException")
+    void rejectsValuesClause() {
+        ValuesAst values = new ValuesAst(List.of(
+                new ValueMappingAst(Map.of(new VarAst("s"), new IriAst("http://example.org/x")))));
+        AskQueryAst ask = new AskQueryAst(
+                DatasetClauseAst.none(), whereOneTriple(), null, null, values);
+
+        assertThrows(UnsupportedOperationException.class, () -> builder.toQuery(ask));
+    }
+
+    @Test
+    @DisplayName("toQuery(null) throws NullPointerException")
+    void rejectsNullAsk() {
+        assertThrows(NullPointerException.class, () -> builder.toQuery(null));
+    }
+
+    @Test
+    @DisplayName("ASK {} with empty WHERE compiles to an empty AND body")
+    void buildsAskWithEmptyWhere() {
+        AskQueryAst ask = new AskQueryAst(DatasetClauseAst.none(),
+                new GroupGraphPatternAst(List.of()));
+
+        Query query = builder.toQuery(ask);
+
+        assertNotNull(query.getBody());
+        assertTrue(query.getBody().isAnd());
+        assertEquals(0, query.getBody().size(), "empty AND — no children");
+        assertTrue(query.isAsk());
+    }
+
+    @Test
+    @DisplayName("Solution modifiers (LIMIT) are not supported yet → UnsupportedOperationException")
+    void rejectsSolutionModifier() {
+        SolutionModifierAst mod = SolutionModifierAst.withoutGroupBy(false, false, List.of(), 10L, null);
+        AskQueryAst ask = new AskQueryAst(DatasetClauseAst.none(), whereOneTriple(), mod, null, null);
+
+        assertThrows(UnsupportedOperationException.class, () -> builder.toQuery(ask));
+    }
+}
\ No newline at end of file