Why do I get the wrong answer from this LP problem?
In this cell, I have a linear programming problem: http://sagecell.sagemath.org/?q=oatgsd
However, the answer is wrong. The optimal objective has to be 1 whereas it is 0. The optimal values for x and y lie on the line between (-2,1) and (1,-2). I have shown the values of the constraints for the point (-1,0)