diff --git a/src/sparql/algebra.rs b/src/sparql/algebra.rs
index 97003d2d..bb46e6c8 100644
--- a/src/sparql/algebra.rs
+++ b/src/sparql/algebra.rs
@@ -1,5 +1,6 @@
 use model::*;
 use sparql::model::*;
+use std::collections::BTreeMap;
 use std::collections::BTreeSet;
 use std::fmt;
 use std::ops::Add;
@@ -234,13 +235,6 @@ pub enum Expression {
     RegexFunctionCall(Box<Expression>, Box<Expression>, Option<Box<Expression>>),
     CustomFunctionCall(NamedNode, Vec<Expression>),
     ExistsFunctionCall(Box<MultiSetPattern>),
-    CountAggregate(Option<Box<Expression>>, bool),
-    SumAggregate(Box<Expression>, bool),
-    MinAggregate(Box<Expression>, bool),
-    MaxAggregate(Box<Expression>, bool),
-    AvgAggregate(Box<Expression>, bool),
-    SampleAggregate(Box<Expression>, bool),
-    GroupConcatAggregate(Box<Expression>, bool, Option<String>),
 }
 
 impl fmt::Display for Expression {
@@ -361,56 +355,6 @@ impl fmt::Display for Expression {
                     .join(", ")
             ),
             Expression::ExistsFunctionCall(p) => write!(f, "EXISTS {{ {} }}", p),
-            Expression::CountAggregate(e, distinct) => if *distinct {
-                e.as_ref()
-                    .map(|ex| write!(f, "COUNT(DISTINCT {})", ex))
-                    .unwrap_or_else(|| write!(f, "COUNT(DISTINCT *)"))
-            } else {
-                e.as_ref()
-                    .map(|ex| write!(f, "COUNT({})", ex))
-                    .unwrap_or_else(|| write!(f, "COUNT(*)"))
-            },
-            Expression::SumAggregate(e, distinct) => if *distinct {
-                write!(f, "SUM(DISTINCT {})", e)
-            } else {
-                write!(f, "SUM({})", e)
-            },
-            Expression::MinAggregate(e, distinct) => if *distinct {
-                write!(f, "MIN(DISTINCT {})", e)
-            } else {
-                write!(f, "MIN({})", e)
-            },
-            Expression::MaxAggregate(e, distinct) => if *distinct {
-                write!(f, "MAX(DISTINCT {})", e)
-            } else {
-                write!(f, "MAX({})", e)
-            },
-            Expression::AvgAggregate(e, distinct) => if *distinct {
-                write!(f, "AVG(DISTINCT {})", e)
-            } else {
-                write!(f, "AVG({})", e)
-            },
-            Expression::SampleAggregate(e, distinct) => if *distinct {
-                write!(f, "SAMPLE(DISTINCT {})", e)
-            } else {
-                write!(f, "SAMPLE({})", e)
-            },
-            Expression::GroupConcatAggregate(e, distinct, sep) => if *distinct {
-                sep.as_ref()
-                    .map(|s| {
-                        write!(
-                            f,
-                            "GROUP_CONCAT(DISTINCT {}; SEPARATOR = \"{}\")",
-                            e,
-                            s.escape()
-                        )
-                    })
-                    .unwrap_or_else(|| write!(f, "GROUP_CONCAT(DISTINCT {})", e))
-            } else {
-                sep.as_ref()
-                    .map(|s| write!(f, "GROUP_CONCAT({}; SEPARATOR = \"{}\")", e, s.escape()))
-                    .unwrap_or_else(|| write!(f, "GROUP_CONCAT({})", e))
-            },
         }
     }
 }
@@ -703,63 +647,6 @@ impl<'a> fmt::Display for SparqlExpression<'a> {
             Expression::ExistsFunctionCall(p) => {
                 write!(f, "EXISTS {{ {} }}", SparqlMultiSetPattern(&*p))
             }
-            Expression::CountAggregate(e, distinct) => if *distinct {
-                e.as_ref()
-                    .map(|ex| write!(f, "COUNT(DISTINCT {})", SparqlExpression(ex)))
-                    .unwrap_or_else(|| write!(f, "COUNT(DISTINCT *)"))
-            } else {
-                e.as_ref()
-                    .map(|ex| write!(f, "COUNT({})", SparqlExpression(ex)))
-                    .unwrap_or_else(|| write!(f, "COUNT(*)"))
-            },
-            Expression::SumAggregate(e, distinct) => if *distinct {
-                write!(f, "SUM(DISTINCT {})", SparqlExpression(e))
-            } else {
-                write!(f, "SUM({})", SparqlExpression(e))
-            },
-            Expression::MinAggregate(e, distinct) => if *distinct {
-                write!(f, "MIN(DISTINCT {})", SparqlExpression(e))
-            } else {
-                write!(f, "MIN({})", SparqlExpression(e))
-            },
-            Expression::MaxAggregate(e, distinct) => if *distinct {
-                write!(f, "MAX(DISTINCT {})", SparqlExpression(e))
-            } else {
-                write!(f, "MAX({})", SparqlExpression(e))
-            },
-            Expression::AvgAggregate(e, distinct) => if *distinct {
-                write!(f, "AVG(DISTINCT {})", SparqlExpression(e))
-            } else {
-                write!(f, "AVG({})", SparqlExpression(e))
-            },
-            Expression::SampleAggregate(e, distinct) => if *distinct {
-                write!(f, "SAMPLE(DISTINCT {})", SparqlExpression(e))
-            } else {
-                write!(f, "SAMPLE({})", SparqlExpression(e))
-            },
-            Expression::GroupConcatAggregate(e, distinct, sep) => if *distinct {
-                sep.as_ref()
-                    .map(|s| {
-                        write!(
-                            f,
-                            "GROUP_CONCAT(DISTINCT {}; SEPARATOR = \"{}\")",
-                            SparqlExpression(e),
-                            s.escape()
-                        )
-                    })
-                    .unwrap_or_else(|| write!(f, "GROUP_CONCAT(DISTINCT {})", SparqlExpression(e)))
-            } else {
-                sep.as_ref()
-                    .map(|s| {
-                        write!(
-                            f,
-                            "GROUP_CONCAT({}; SEPARATOR = \"{}\")",
-                            SparqlExpression(e),
-                            s.escape()
-                        )
-                    })
-                    .unwrap_or_else(|| write!(f, "GROUP_CONCAT({})", SparqlExpression(e)))
-            },
         }
     }
 }
@@ -776,6 +663,7 @@ pub enum MultiSetPattern {
     Minus(Box<MultiSetPattern>, Box<MultiSetPattern>),
     ToMultiSet(Box<ListPattern>),
     Service(NamedNodeOrVariable, Box<MultiSetPattern>, bool),
+    AggregateJoin(GroupPattern, BTreeMap<Aggregation, Variable>),
 }
 
 impl fmt::Display for MultiSetPattern {
@@ -798,6 +686,15 @@ impl fmt::Display for MultiSetPattern {
             MultiSetPattern::Minus(a, b) => write!(f, "Minus({}, {})", a, b),
             MultiSetPattern::ToMultiSet(l) => write!(f, "{}", l),
             MultiSetPattern::Service(n, p, s) => write!(f, "Service({}, {}, {})", n, p, s),
+            MultiSetPattern::AggregateJoin(g, a) => write!(
+                f,
+                "AggregateJoin({}, {})",
+                g,
+                a.iter()
+                    .map(|(a, v)| format!("{}: {}", v, a))
+                    .collect::<Vec<String>>()
+                    .join(", ")
+            ),
         }
     }
 }
@@ -878,6 +775,7 @@ impl MultiSetPattern {
             MultiSetPattern::Minus(a, _) => a.add_visible_variables(vars),
             MultiSetPattern::ToMultiSet(l) => l.add_visible_variables(vars),
             MultiSetPattern::Service(_, p, _) => p.add_visible_variables(vars),
+            MultiSetPattern::AggregateJoin(_, a) => vars.extend(a.iter().map(|(_, v)| v)),
         }
     }
 }
@@ -960,10 +858,42 @@ impl<'a> fmt::Display for SparqlMultiSetPattern<'a> {
             } else {
                 write!(f, "SERVICE {} {{ {} }}", n, SparqlMultiSetPattern(&*p))
             },
+            MultiSetPattern::AggregateJoin(GroupPattern(group, p), agg) => write!(
+                f,
+                "{{ SELECT {} WHERE {{ {} }} GROUP BY {} }}",
+                agg.iter()
+                    .map(|(a, v)| format!("({} AS {})", SparqlAggregation(&a), v))
+                    .collect::<Vec<String>>()
+                    .join(" "),
+                SparqlMultiSetPattern(p),
+                group
+                    .iter()
+                    .map(|e| format!("({})", e.to_string()))
+                    .collect::<Vec<String>>()
+                    .join(" ")
+            ),
         }
     }
 }
 
+#[derive(Eq, PartialEq, Ord, PartialOrd, Debug, Clone, Hash)]
+pub struct GroupPattern(pub Vec<Expression>, pub Box<MultiSetPattern>);
+
+impl fmt::Display for GroupPattern {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        write!(
+            f,
+            "Group(({}), {})",
+            self.0
+                .iter()
+                .map(|c| c.to_string())
+                .collect::<Vec<String>>()
+                .join(", "),
+            self.1
+        )
+    }
+}
+
 #[derive(Eq, PartialEq, Ord, PartialOrd, Debug, Clone, Hash)]
 pub enum ListPattern {
     Data(Vec<Binding>),
@@ -1191,6 +1121,147 @@ fn build_sparql_select_arguments(args: &Vec<Variable>) -> String {
     }
 }
 
+#[derive(Eq, PartialEq, Ord, PartialOrd, Debug, Clone, Hash)]
+pub enum Aggregation {
+    Count(Option<Box<Expression>>, bool),
+    Sum(Box<Expression>, bool),
+    Min(Box<Expression>, bool),
+    Max(Box<Expression>, bool),
+    Avg(Box<Expression>, bool),
+    Sample(Box<Expression>, bool),
+    GroupConcat(Box<Expression>, bool, Option<String>),
+}
+
+impl fmt::Display for Aggregation {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        match self {
+            Aggregation::Count(e, distinct) => if *distinct {
+                e.as_ref()
+                    .map(|ex| write!(f, "COUNT(DISTINCT {})", ex))
+                    .unwrap_or_else(|| write!(f, "COUNT(DISTINCT *)"))
+            } else {
+                e.as_ref()
+                    .map(|ex| write!(f, "COUNT({})", ex))
+                    .unwrap_or_else(|| write!(f, "COUNT(*)"))
+            },
+            Aggregation::Sum(e, distinct) => if *distinct {
+                write!(f, "Aggregation(Distinct({}), Sum, {{}})", e)
+            } else {
+                write!(f, "Aggregation({}, Sum, {{}})", e)
+            },
+            Aggregation::Min(e, distinct) => if *distinct {
+                write!(f, "Aggregation(Distinct({}), Min, {{}})", e)
+            } else {
+                write!(f, "Aggregation({}, Min, {{}})", e)
+            },
+            Aggregation::Max(e, distinct) => if *distinct {
+                write!(f, "Aggregation(Distinct({}), Max, {{}})", e)
+            } else {
+                write!(f, "Aggregation({}, Max, {{}})", e)
+            },
+            Aggregation::Avg(e, distinct) => if *distinct {
+                write!(f, "Aggregation(Distinct({}), Avg, {{}})", e)
+            } else {
+                write!(f, "Aggregation({}, Avg, {{}})", e)
+            },
+            Aggregation::Sample(e, distinct) => if *distinct {
+                write!(f, "Aggregation(Distinct({}), Sum, {{}})", e)
+            } else {
+                write!(f, "Aggregation({}, Sample, {{}})", e)
+            },
+            Aggregation::GroupConcat(e, distinct, sep) => if *distinct {
+                sep.as_ref()
+                    .map(|s| {
+                        write!(
+                            f,
+                            "Aggregation(Distinct({}), GroupConcat, {{\"separator\" → \"{}\"}})",
+                            e,
+                            s.escape()
+                        )
+                    })
+                    .unwrap_or_else(|| write!(f, "Aggregation(Distinct({}), GroupConcat, {{}})", e))
+            } else {
+                sep.as_ref()
+                    .map(|s| {
+                        write!(
+                            f,
+                            "Aggregation({}, GroupConcat, {{\"separator\" → \"{}\"}})",
+                            e,
+                            s.escape()
+                        )
+                    })
+                    .unwrap_or_else(|| write!(f, "Aggregation(Distinct({}), GroupConcat, {{}})", e))
+            },
+        }
+    }
+}
+
+struct SparqlAggregation<'a>(&'a Aggregation);
+
+impl<'a> fmt::Display for SparqlAggregation<'a> {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        match self.0 {
+            Aggregation::Count(e, distinct) => if *distinct {
+                e.as_ref()
+                    .map(|ex| write!(f, "COUNT(DISTINCT {})", SparqlExpression(ex)))
+                    .unwrap_or_else(|| write!(f, "COUNT(DISTINCT *)"))
+            } else {
+                e.as_ref()
+                    .map(|ex| write!(f, "COUNT({})", SparqlExpression(ex)))
+                    .unwrap_or_else(|| write!(f, "COUNT(*)"))
+            },
+            Aggregation::Sum(e, distinct) => if *distinct {
+                write!(f, "SUM(DISTINCT {})", SparqlExpression(e))
+            } else {
+                write!(f, "SUM({})", SparqlExpression(e))
+            },
+            Aggregation::Min(e, distinct) => if *distinct {
+                write!(f, "MIN(DISTINCT {})", SparqlExpression(e))
+            } else {
+                write!(f, "MIN({})", SparqlExpression(e))
+            },
+            Aggregation::Max(e, distinct) => if *distinct {
+                write!(f, "MAX(DISTINCT {})", SparqlExpression(e))
+            } else {
+                write!(f, "MAX({})", SparqlExpression(e))
+            },
+            Aggregation::Avg(e, distinct) => if *distinct {
+                write!(f, "AVG(DISTINCT {})", SparqlExpression(e))
+            } else {
+                write!(f, "AVG({})", SparqlExpression(e))
+            },
+            Aggregation::Sample(e, distinct) => if *distinct {
+                write!(f, "SAMPLE(DISTINCT {})", SparqlExpression(e))
+            } else {
+                write!(f, "SAMPLE({})", SparqlExpression(e))
+            },
+            Aggregation::GroupConcat(e, distinct, sep) => if *distinct {
+                sep.as_ref()
+                    .map(|s| {
+                        write!(
+                            f,
+                            "GROUP_CONCAT(DISTINCT {}; SEPARATOR = \"{}\")",
+                            SparqlExpression(e),
+                            s.escape()
+                        )
+                    })
+                    .unwrap_or_else(|| write!(f, "GROUP_CONCAT(DISTINCT {})", SparqlExpression(e)))
+            } else {
+                sep.as_ref()
+                    .map(|s| {
+                        write!(
+                            f,
+                            "GROUP_CONCAT({}; SEPARATOR = \"{}\")",
+                            SparqlExpression(e),
+                            s.escape()
+                        )
+                    })
+                    .unwrap_or_else(|| write!(f, "GROUP_CONCAT({})", SparqlExpression(e)))
+            },
+        }
+    }
+}
+
 #[derive(Eq, PartialEq, Ord, PartialOrd, Debug, Clone, Hash)]
 pub enum OrderComparator {
     Asc(Expression),
diff --git a/src/sparql/model.rs b/src/sparql/model.rs
index 3b779b99..1afa2520 100644
--- a/src/sparql/model.rs
+++ b/src/sparql/model.rs
@@ -24,7 +24,7 @@ impl fmt::Display for Variable {
 impl Default for Variable {
     fn default() -> Self {
         Self {
-            name: Uuid::new_v4().to_string(),
+            name: Uuid::new_v4().simple().to_string(),
         }
     }
 }
diff --git a/src/sparql/parser.rs b/src/sparql/parser.rs
index 71e64f1c..831cb90f 100644
--- a/src/sparql/parser.rs
+++ b/src/sparql/parser.rs
@@ -177,18 +177,43 @@ mod grammar {
     fn build_select(
         select: Selection,
         wher: MultiSetPattern,
+        group: Option<(Vec<Expression>, Vec<(Expression, Variable)>)>,
         having: Option<Expression>,
         order_by: Option<Vec<OrderComparator>>,
         offset_limit: Option<(usize, Option<usize>)>,
         values: Option<MultiSetPattern>,
+        state: &mut ParserState,
     ) -> ListPattern {
         let mut p = wher;
+
+        //GROUP BY
+        if let Some((clauses, binds)) = group {
+            for (e, v) in binds {
+                p = MultiSetPattern::Extend(Box::new(p), v, e);
+            }
+            let g = GroupPattern(clauses, Box::new(p));
+            p = MultiSetPattern::AggregateJoin(g, state.aggregations.clone());
+            state.aggregations = BTreeMap::default();
+        }
+        if !state.aggregations.is_empty() {
+            let g = GroupPattern(vec![Literal::from(1).into()], Box::new(p));
+            p = MultiSetPattern::AggregateJoin(g, state.aggregations.clone());
+            state.aggregations = BTreeMap::default();
+        }
+
+        //TODO: not aggregated vars
+
+        //HAVING
         if let Some(ex) = having {
             p = MultiSetPattern::Filter(ex, Box::new(p));
         }
+
+        //VALUES
         if let Some(data) = values {
             p = MultiSetPattern::Join(Box::new(p), Box::new(data));
         }
+
+        //SELECT
         let mut pv: Vec<Variable> = Vec::default();
         match select.variables {
             Some(sel_items) => {
@@ -209,15 +234,21 @@ mod grammar {
             }
         }
         let mut m = ListPattern::from(p);
+
+        //ORDER BY
         if let Some(order) = order_by {
             m = ListPattern::OrderBy(Box::new(m), order);
         }
+
+        //PROJECT
         m = ListPattern::Project(Box::new(m), pv);
         match select.option {
             SelectionOption::Distinct => m = ListPattern::Distinct(Box::new(m)),
             SelectionOption::Reduced => m = ListPattern::Reduced(Box::new(m)),
             SelectionOption::Default => (),
         }
+
+        //OFFSET LIMIT
         if let Some((offset, limit)) = offset_limit {
             m = ListPattern::Slice(Box::new(m), offset, limit)
         }
@@ -233,12 +264,24 @@ mod grammar {
         base_uri: Option<Url>,
         namespaces: HashMap<String, String>,
         bnodes_map: BTreeMap<String, BlankNode>,
+        aggregations: BTreeMap<Aggregation, Variable>,
     }
 
     impl ParserState {
         fn url_parser<'a>(&'a self) -> ParseOptions<'a> {
             Url::options().base_url(self.base_uri.as_ref())
         }
+
+        fn new_aggregation(&mut self, agg: Aggregation) -> Variable {
+            self.aggregations
+                .get(&agg)
+                .map(|v| v.clone())
+                .unwrap_or_else(|| {
+                    let new_var = Variable::default();
+                    self.aggregations.insert(agg, new_var.clone());
+                    new_var
+                })
+        }
     }
 
     include!(concat!(env!("OUT_DIR"), "/sparql_grammar.rs"));
@@ -251,6 +294,7 @@ mod grammar {
             base_uri: base_uri.into(),
             namespaces: HashMap::default(),
             bnodes_map: BTreeMap::default(),
+            aggregations: BTreeMap::default(),
         };
 
         let mut string_buffer = String::default();
diff --git a/src/sparql/sparql_grammar.rustpeg b/src/sparql/sparql_grammar.rustpeg
index ff4dd980..398819ef 100644
--- a/src/sparql/sparql_grammar.rustpeg
+++ b/src/sparql/sparql_grammar.rustpeg
@@ -38,16 +38,16 @@ PrefixDecl -> () = "PREFIX"i _ ns:PNAME_NS _ i:IRIREF {
 }
 
 //[7]
-SelectQuery -> Query = s:SelectClause _ d:DatasetClauses _ w:WhereClause _ GroupClause? _ h:HavingClause? _ o:OrderClause? _ l:LimitOffsetClauses? _ v:ValuesClause {  //TODO: Modifier
+SelectQuery -> Query = s:SelectClause _ d:DatasetClauses _ w:WhereClause _ g:GroupClause? _ h:HavingClause? _ o:OrderClause? _ l:LimitOffsetClauses? _ v:ValuesClause {  //TODO: Modifier
     Query::SelectQuery {
         dataset: d,
-        algebra: build_select(s, w, h, o, l, v)
+        algebra: build_select(s, w, g, h, o, l, v, state)
     }
 }
 
 //[8]
-SubSelect -> MultiSetPattern = s:SelectClause _ w:WhereClause _ GroupClause? _ h:HavingClause? _ o:OrderClause? _ l:LimitOffsetClauses? _ v:ValuesClause { //TODO: Modifiers
-    build_select(s, w, h, o, l, v).into()
+SubSelect -> MultiSetPattern = s:SelectClause _ w:WhereClause _ g:GroupClause? _ h:HavingClause? _ o:OrderClause? _ l:LimitOffsetClauses? _ v:ValuesClause { //TODO: Modifiers
+    build_select(s, w, g, h, o, l, v, state).into()
 }
 
 //[9]
@@ -70,21 +70,21 @@ SelectClause_member -> SelectionMember =
 
 //[10]
 ConstructQuery -> Query =
-    "CONSTRUCT"i _ c:ConstructTemplate _ d:DatasetClauses _ w:WhereClause _ GroupClause? _ h:HavingClause? _ o:OrderClause? _ l:LimitOffsetClauses? _ v:ValuesClause {
+    "CONSTRUCT"i _ c:ConstructTemplate _ d:DatasetClauses _ w:WhereClause _ g:GroupClause? _ h:HavingClause? _ o:OrderClause? _ l:LimitOffsetClauses? _ v:ValuesClause {
         Query::ConstructQuery {
             construct: c,
             dataset: d,
-            algebra: build_select(Selection::default(), w, h, o, l, v)
+            algebra: build_select(Selection::default(), w, g, h, o, l, v, state)
         }
     } /
-    "CONSTRUCT"i _ d:DatasetClauses _ "WHERE"i _ '{' _ c:ConstructQuery_optional_triple_template _ '}' _ GroupClause? _ h:HavingClause? _ o:OrderClause? _ l:LimitOffsetClauses? _ v:ValuesClause {
+    "CONSTRUCT"i _ d:DatasetClauses _ "WHERE"i _ '{' _ c:ConstructQuery_optional_triple_template _ '}' _ g:GroupClause? _ h:HavingClause? _ o:OrderClause? _ l:LimitOffsetClauses? _ v:ValuesClause {
         Query::ConstructQuery {
             construct: c.clone(),
             dataset: d,
             algebra: build_select(
                 Selection::default(),
                 MultiSetPattern::BGP(c.into_iter().map(|p| TripleOrPathPattern::from(p)).collect()).into(),
-                h, o, l, v
+                g, h, o, l, v, state
             )
         }
     }
@@ -93,13 +93,13 @@ ConstructQuery_optional_triple_template -> Vec<TriplePattern> = TriplesTemplate
 
 //[11]
 DescribeQuery -> Query =
-    "DESCRIBE"i _ '*' _ d:DatasetClauses w:WhereClause? _ GroupClause? _ h:HavingClause? _ o:OrderClause? _ l:LimitOffsetClauses? _ v:ValuesClause {
+    "DESCRIBE"i _ '*' _ d:DatasetClauses w:WhereClause? _ g:GroupClause? _ h:HavingClause? _ o:OrderClause? _ l:LimitOffsetClauses? _ v:ValuesClause {
         Query::DescribeQuery {
             dataset: d,
-            algebra: build_select(Selection::default(), w.unwrap_or_else(MultiSetPattern::default), h, o, l, v)
+            algebra: build_select(Selection::default(), w.unwrap_or_else(MultiSetPattern::default), g, h, o, l, v, state)
         }
     } /
-    "DESCRIBE"i _ p:DescribeQuery_item+ _ d:DatasetClauses w:WhereClause? _ GroupClause? _ h:HavingClause? _ o:OrderClause? _ l:LimitOffsetClauses? _ v:ValuesClause {
+    "DESCRIBE"i _ p:DescribeQuery_item+ _ d:DatasetClauses w:WhereClause? _ g:GroupClause? _ h:HavingClause? _ o:OrderClause? _ l:LimitOffsetClauses? _ v:ValuesClause {
         Query::DescribeQuery {
             dataset: d,
             algebra: build_select(Selection {
@@ -108,16 +108,16 @@ DescribeQuery -> Query =
                     NamedNodeOrVariable::NamedNode(n) => SelectionMember::Expression(n.into(), Variable::default()),
                     NamedNodeOrVariable::Variable(v) => SelectionMember::Variable(v)
                 }).collect())
-            }, w.unwrap_or_else(MultiSetPattern::default), h, o, l, v)
+            }, w.unwrap_or_else(MultiSetPattern::default), g, h, o, l, v, state)
         }
     }
 DescribeQuery_item -> NamedNodeOrVariable = i:VarOrIri _ { i }
 
 //[12]
-AskQuery -> Query = "ASK"i _ d:DatasetClauses w:WhereClause _ GroupClause? _ h:HavingClause? _ o:OrderClause? _ l:LimitOffsetClauses? _ v:ValuesClause {
+AskQuery -> Query = "ASK"i _ d:DatasetClauses w:WhereClause _ g:GroupClause? _ h:HavingClause? _ o:OrderClause? _ l:LimitOffsetClauses? _ v:ValuesClause {
     Query::AskQuery {
         dataset: d,
-        algebra: build_select(Selection::default(), w, h, o, l, v)
+        algebra: build_select(Selection::default(), w, g, h, o, l, v, state)
     }
 }
 
@@ -146,10 +146,28 @@ WhereClause -> MultiSetPattern = "WHERE"i? _ p:GroupGraphPattern {
 }
 
 //[19]
-GroupClause -> () = "GROUP"i _ "BY"i _ (GroupCondition _)+
+GroupClause -> (Vec<Expression>, Vec<(Expression,Variable)>) = "GROUP"i _ "BY"i _ c:GroupCondition_item+ {
+    let mut projections: Vec<(Expression,Variable)> = Vec::default();
+    let clauses = c.into_iter().map(|(e, vo)| {
+        match vo {
+            Some(v) => {
+                projections.push((e, v.clone()));
+                v.into()
+            },
+            None => e
+        }
+    }).collect();
+    (clauses, projections)
+}
+GroupCondition_item -> (Expression, Option<Variable>) = c:GroupCondition _ { c }
 
 //[20]
-GroupCondition -> () = BuiltInCall / FunctionCall / '(' _ Expression _ ("AS"i _ Var _)? ')' / Var
+GroupCondition -> (Expression, Option<Variable>) =
+    e:BuiltInCall { (e, None) } /
+    e:FunctionCall { (e, None) } /
+    '(' _ e:Expression _ v:GroupCondition_as? ')' { (e, v) } /
+    e:Var { (e.into(), None) }
+GroupCondition_as -> Variable = "AS"i _ v:Var _ { v }
 
 //[21]
 HavingClause -> Expression = "HAVING"i _ e:HavingCondition+ {?
@@ -737,7 +755,7 @@ BrackettedExpression -> Expression = '(' _ e:Expression _ ')' { e }
 
 //[121]
 BuiltInCall -> Expression =
-    Aggregate /
+    a:Aggregate { state.new_aggregation(a).into() } /
     "STR"i _ '(' _ e:Expression _ ')' { Expression::StrFunctionCall(Box::new(e)) } /
     "LANG"i _ '(' _ e:Expression _ ')' { Expression::LangFunctionCall(Box::new(e)) } /
     "LANGMATCHES"i _ '(' _ a:Expression _ ',' _ b:Expression _ ')' { Expression::LangMatchesFunctionCall(Box::new(a), Box::new(b)) } /
@@ -814,25 +832,25 @@ ExistsFunc -> Expression = "EXISTS"i _ p:GroupGraphPattern { Expression::ExistsF
 NotExistsFunc -> Expression = "NOT"i _ "EXISTS"i _ p:GroupGraphPattern { Expression::UnaryNotExpression(Box::new(Expression::ExistsFunctionCall(Box::new(p)))) }
 
 //[127]
-Aggregate -> Expression =
-    "COUNT"i _ '(' _ "DISTINCT"i _ '*' _ ')' { Expression::CountAggregate(None, true) } /
-    "COUNT"i _ '(' _ "DISTINCT"i _ e:Expression _ ')' { Expression::CountAggregate(Some(Box::new(e)), true) } /
-    "COUNT"i _ '(' _ '*' _ ')' { Expression::CountAggregate(None, false) } /
-    "COUNT"i _ '(' _ e:Expression _ ')' { Expression::CountAggregate(Some(Box::new(e)), false) } /
-    "SUM"i _ '(' _ "DISTINCT"i _ e:Expression _ ')' { Expression::SumAggregate(Box::new(e), true) } /
-    "SUM"i _ '(' _ e:Expression _ ')' { Expression::SumAggregate(Box::new(e), false) } /
-    "MIN"i _ '(' _ "DISTINCT"i _ e:Expression _ ')' { Expression::MinAggregate(Box::new(e), true) } /
-    "MIN"i _ '(' _ e:Expression _ ')' { Expression::MinAggregate(Box::new(e), false) } /
-    "MAX"i _ '(' _ "DISTINCT"i _ e:Expression _ ')' { Expression::MaxAggregate(Box::new(e), true) } /
-    "MAX"i _ '(' _ e:Expression _ ')' { Expression::MaxAggregate(Box::new(e), false) } /
-    "AVG"i _ '(' _ "DISTINCT"i _ e:Expression _ ')' { Expression::AvgAggregate(Box::new(e), true) } /
-    "AVG"i _ '(' _ e:Expression _ ')' { Expression::AvgAggregate(Box::new(e), false) } /
-    "SAMPLE"i _ '(' _ "DISTINCT"i _ e:Expression _ ')' { Expression::SampleAggregate(Box::new(e), true) } /
-    "SAMPLE"i _ '(' _ e:Expression _ ')' { Expression::SampleAggregate(Box::new(e), false) } /
-    "GROUP_CONCAT"i _ '(' _ "DISTINCT"i _ e:Expression _ ';' _ 'SEPARATOR'i _ '=' _ s:String _ ')' { Expression::GroupConcatAggregate(Box::new(e), true, Some(s)) } /
-    "GROUP_CONCAT"i _ '(' _ "DISTINCT"i _ e:Expression _ ')' { Expression::GroupConcatAggregate(Box::new(e), true, None) } /
-    "GROUP_CONCAT"i _ '(' _ e:Expression _ ';' _ 'SEPARATOR'i _ '=' _ s:String _ ')' { Expression::GroupConcatAggregate(Box::new(e), true, Some(s)) } /
-    "GROUP_CONCAT"i _ '(' _ e:Expression _ ')' { Expression::GroupConcatAggregate(Box::new(e), false, None) }
+Aggregate -> Aggregation =
+    "COUNT"i _ '(' _ "DISTINCT"i _ '*' _ ')' { Aggregation::Count(None, true) } /
+    "COUNT"i _ '(' _ "DISTINCT"i _ e:Expression _ ')' { Aggregation::Count(Some(Box::new(e)), true) } /
+    "COUNT"i _ '(' _ '*' _ ')' { Aggregation::Count(None, false) } /
+    "COUNT"i _ '(' _ e:Expression _ ')' { Aggregation::Count(Some(Box::new(e)), false) } /
+    "SUM"i _ '(' _ "DISTINCT"i _ e:Expression _ ')' { Aggregation::Sum(Box::new(e), true) } /
+    "SUM"i _ '(' _ e:Expression _ ')' { Aggregation::Sum(Box::new(e), false) } /
+    "MIN"i _ '(' _ "DISTINCT"i _ e:Expression _ ')' { Aggregation::Min(Box::new(e), true) } /
+    "MIN"i _ '(' _ e:Expression _ ')' { Aggregation::Min(Box::new(e), false) } /
+    "MAX"i _ '(' _ "DISTINCT"i _ e:Expression _ ')' { Aggregation::Max(Box::new(e), true) } /
+    "MAX"i _ '(' _ e:Expression _ ')' { Aggregation::Max(Box::new(e), false) } /
+    "AVG"i _ '(' _ "DISTINCT"i _ e:Expression _ ')' { Aggregation::Avg(Box::new(e), true) } /
+    "AVG"i _ '(' _ e:Expression _ ')' { Aggregation::Avg(Box::new(e), false) } /
+    "SAMPLE"i _ '(' _ "DISTINCT"i _ e:Expression _ ')' { Aggregation::Sample(Box::new(e), true) } /
+    "SAMPLE"i _ '(' _ e:Expression _ ')' { Aggregation::Sample(Box::new(e), false) } /
+    "GROUP_CONCAT"i _ '(' _ "DISTINCT"i _ e:Expression _ ';' _ 'SEPARATOR'i _ '=' _ s:String _ ')' { Aggregation::GroupConcat(Box::new(e), true, Some(s)) } /
+    "GROUP_CONCAT"i _ '(' _ "DISTINCT"i _ e:Expression _ ')' { Aggregation::GroupConcat(Box::new(e), true, None) } /
+    "GROUP_CONCAT"i _ '(' _ e:Expression _ ';' _ 'SEPARATOR'i _ '=' _ s:String _ ')' { Aggregation::GroupConcat(Box::new(e), true, Some(s)) } /
+    "GROUP_CONCAT"i _ '(' _ e:Expression _ ')' { Aggregation::GroupConcat(Box::new(e), false, None) }
 
 //[128]
 iriOrFunction -> Expression =