If he is pulling on your tie downward then you go down in the direction of the force and with the side of your fist take out his knee and/or go to the groin. If he is pulling up, don't grab the tie, grab one of his fingers on the tie and break it off. He will let go of the tie. Then take out his knee as described above or with your foot. Once you have incapacitated him you run as fast as you can in another direction then drop to your knees and thank God you are still alive.