|yehuda ben shimol|
First a remark, Plot[Point[x1,y1]] will not work. You need Show[Graphics[Point[ ... instead, but as you will see later this is not the not the way Mathematica works. Since each plot generates a Graphics object, each of your Plot[Point[ ... command will generate a new object and to see a all points together on a single graph youe have to use Show.
The best way is to "list" all points and then use PlotList or other