VAR

  a[4]

ASSIGN

  init(a) := 0;

  next(a) :=
    case
      a = 9 : 0;		-- simulate modulo 10
      1 : inc(a);
    esac;

-- SPEC AG !(a = 11 | a = 12 | a = 13 | a = 14 | a = 15)
SPEC AG a != 10
