Dear,

I'm trying to reproduce in Maple an integer linear programming example from Chvatal's book: 

Maximize z= 4x₁ + 5x₂ + 5x₃ + 2x₄

Subject to 33x₁ + 49x₂ +51x₃ + 22x₄ <= 120,  x_i = nonnegative integers. 

The optimal solution is: x₁ = 2,   x₂ = 1,  x₃ = x₄ = 0,     z=  13.

In Maple I type: 

 LPSolve( 4x₁ + 5x₂ + 5x₃ + 2x₄, {33x₁ + 49x₂ +51x₃ + 22x₄ <= 120}, maximize, assume ={nonnegative, integer}); 

but Maple gives me back the following error: 

Warning, problem appears to be unbounded. [0, [x₁ =0, x₂ =0, x₃ =0, x₄ =0]]

I know the example has the abovementioned definite solution since it comes from the textbook. So, what could I be doing wrongly? 

Many thanks for your help. 

Dear all

When requesting Maple to solve, for example, the 2D Laplace equation the default solution is 

U(x, y) = _F1(y-I*x)+_F2(y+I*x)

How can I ask Maple to provide a solution in real variables? I've tried  "assuming U(x,y) real", but the result is the same. 

Thank you very much for your help.