# calculating the extreme rays of a polyhedra

How could I go about the problem finding the extreme rays of a polyhedral defined by constraints

$$x_1-x_2 \geq -2$$

$$x_1+x_2 \geq 1$$

$$x_1,x_2 \geq 0$$

I know for certain that given a max or min problem in standard form, using the simplex method, if the optimal cost is at -∞, then the algorithm will terminate at an extreme ray. My issue here is that the problem just defines constraints with no objective function.