rule "arithmetic operators"
when
    1.0 + 1.0 == 2.0 &&
    8 * 2 > 15 &&
    double_valued_func() / 20.0 == 0.0 &&
    21 % 20 == 1 &&
    10.0 / 20.0 == 0.5 &&
    +10.0 / -5.0 == -2.0 &&
    -double_valued_func() == -0.0 &&
    double_valued_func() + 1.0 > 0.0
then
    trigger_test();
end