Document( 
 Prefix(xs <http://www.w3.org/2001/XMLSchema#>)
 Prefix(pred <http://www.w3.org/2007/rif-builtin-predicate#>) 
 Prefix(ex <http://example.org/example#>)

 Group ( 
  ex:ok() :- 
    And (
     External( pred:is-literal-boolean( "1"^^xs:boolean ) )
     External( pred:is-literal-not-boolean( "foo"^^xs:string ) )
     External( pred:is-literal-boolean( External ( xs:boolean ( "1"^^xs:string ) ) ) )
     External ( pred:boolean-equal( "0"^^xs:boolean "0"^^xs:boolean ) )
     External ( pred:boolean-less-than( "0"^^xs:boolean "1"^^xs:boolean ) )
     External ( pred:boolean-greater-than( "1"^^xs:boolean "0"^^xs:boolean ) )
    )
 )
)