4 files changed, 9 insertions, 5 deletions
diff --git a/bsfs/graph/schema.nt b/bsfs/graph/schema.nt
index 8612681..f619746 100644
--- a/bsfs/graph/schema.nt
+++ b/bsfs/graph/schema.nt
@@ -8,7 +8,8 @@ prefix bsfs: <http://bsfs.ai/schema/>
 prefix bsm: <http://bsfs.ai/schema/Meta#>
 
 # literals
-xsd:integer rdfs:subClassOf bsfs:Literal .
+bsfs:Number rdfs:subClassOf bsfs:Literal .
+xsd:integer rdfs:subClassOf bsfs:Number .
 
 # predicates
 bsm:t_created rdfs:subClassOf bsfs:Predicate ;
diff --git a/bsfs/query/validator.py b/bsfs/query/validator.py
index b04a9bf..75b51ca 100644
--- a/bsfs/query/validator.py
+++ b/bsfs/query/validator.py
@@ -182,8 +182,7 @@ class Filter():
         if not type_ <= dom:
             raise errors.ConsistencyError(f'expected type {dom}, found {type_}')
         # node.count is a numerical expression
-        # FIXME: We have to ensure that ns.xsd.integer is always known in the schema!
-        self._parse_filter_expression(self.schema.literal(ns.xsd.integer), node.count)
+        self._parse_filter_expression(self.schema.literal(ns.bsfs.Number), node.count)
 
 
     ## conditions
@@ -211,6 +210,9 @@ class Filter():
         # type exists in the schema
         if type_ not in self.schema.literals():
             raise errors.ConsistencyError(f'literal {type_} is not in the schema')
+        # type must be a numerical
+        if not type_ <= self.schema.literal(ns.bsfs.Number):
+            raise errors.ConsistencyError(f'expected a number type, found {type_}')
         # FIXME: Check if node.value corresponds to type_
 
 
diff --git a/bsfs/triple_store/sparql/parse_filter.py b/bsfs/triple_store/sparql/parse_filter.py
index 0297cbc..18a3288 100644
--- a/bsfs/triple_store/sparql/parse_filter.py
+++ b/bsfs/triple_store/sparql/parse_filter.py
@@ -242,7 +242,6 @@ class Filter():
         # predicate count expression (fetch number of predicates at *head*)
         num_preds = f'{{ SELECT (COUNT(distinct {inner}) as {outer}) WHERE {{ {head} {pred} {inner} }} }}'
         # count expression
-        # FIXME: We have to ensure that ns.xsd.integer is always known in the schema!
         count_bounds = self._parse_filter_expression(self.schema.literal(ns.xsd.integer), node.count, outer)
         # combine
         return num_preds + ' . ' + count_bounds
diff --git a/bsfs/triple_store/sparql/sparql.py b/bsfs/triple_store/sparql/sparql.py
index ddace35..87467ff 100644
--- a/bsfs/triple_store/sparql/sparql.py
+++ b/bsfs/triple_store/sparql/sparql.py
@@ -11,6 +11,7 @@ import rdflib
 
 # bsfs imports
 from bsfs import schema as bsc
+from bsfs.namespace import ns
 from bsfs.query import ast
 from bsfs.utils import errors, URI
 
@@ -94,7 +95,8 @@ class SparqlStore(base.TripleStoreBase):
         super().__init__(None)
         self._graph = rdflib.Graph()
         self._transaction = _Transaction(self._graph)
-        self._schema = bsc.Schema()
+        # NOTE: parsing bsfs.query.ast.filter.Has requires xsd:integer.
+        self._schema = bsc.Schema(literals={bsc.ROOT_NUMBER.child(ns.xsd.integer)})
         self._filter_parser = parse_filter.Filter(self._schema)
 
     # NOTE: mypy and pylint complain about the **kwargs not being listed (contrasting super)