src/HOL/Tools/Sledgehammer/sledgehammer.ML

   Scan.this_string set_ClauseFormulaRelationN |-- $$ "("
   |-- Scan.repeat parse_clause_formula_pair
 val extract_clause_formula_relation =
   Substring.full #> Substring.position set_ClauseFormulaRelationN
   #> snd #> Substring.position "." #> fst #> Substring.string
-  #> explode #> filter_out (curry (op =) " ") #> parse_clause_formula_relation
+  #> explode #> filter_out Symbol.is_blank #> parse_clause_formula_relation
   #> fst
 
 (* TODO: move to "Sledgehammer_Reconstruct" *)
 fun repair_conjecture_shape_and_theorem_names output conjecture_shape
                                               axiom_names =