src/HOL/SMT/Examples/cert/z3_arith_quant_16

misc tuning and clarification;

(benchmark Isabelle
:assumption (not (exists (?x1 Int) (forall (?x2 Int) (?x3 Real) (implies (and (< 0 ?x2) (< 0.0 ?x3)) (< (~ 1) ?x2)))))
:formula true
)