argument : HouseIsSafe
A1 "House is safe" {
    supported by
        Fact1 "it is protected by plants"

}

A2 "House is not safe" round 1
with ! A1
{
    supported by
        Fact4 "zombies can enter the house" round 1
        replacing Fact1
        with ! Fact1
        {
            supported by
                Fact2 "zombies are coming" round 1

                Fact3 "zombies eat plants" round 1

        }

}