src/HOL/SMT/Examples/cert/z3_arith_quant_18

eliminated separate stamp -- NameSpace.define/merge etc. ensure uniqueness already;
fully authentic merge;

(benchmark Isabelle
:extrafuns (
  (uf_1 Int)
 )
:assumption (not (forall (?x1 Int) (implies (< ?x1 uf_1) (< (* 2 ?x1) (* 2 uf_1))) :pat{ ?x1 }))
:formula true
)