MATP6640/ISYE6770 Linear and Conic Optimization, Homework 1.

Due: 11.59pm on Friday, January 19, 2024 on LMS.
10% penalty for each day late.

  1. Let (P) be the standard form LP, min{cT x : Ax = b,x 0}. In class, we saw that if a problem of the form (P) has a feasible solution then it has a basic feasible solution. Construct a similar proof to show that if (P) has an optimal solution, it has a basic feasible solution that is optimal.
  2. Assume it is known that the fractional linear program
                 T
min          cdT-x+xg+h-

subject to  Ax  ≥   b

    has an optimal value in the range [α,β]. In addition, assume that any x satisfying Ax b also satisfies dT x + h > 0. Develop a procedure that uses linear programming as a subroutine to find the optimal value of the fractional linear program, to within any desired tolerance. (Hint: Consider the problem of determining whether the optimal value is above or below a given threshold τ.)

  3. Consider the linear program
    min   x1      -  x3  +   5x4  -   x5
s.t.  x       -  x   +   3x   -   x   =   1
       1          3        4        5
          x2  +  x3  +   4x4  +  2x5  =   4
                     -    x4  +  3x5  =   0
                            x1,...,x5  ≥   0

    The point x = (1,4,0,0,0)T is a basic feasible solution for this problem. Find all the bases corresponding to this bfs. Use complementary slackness to show that this point is optimal. Find at least 2 optimal dual solutions.

  4. Let A m×n and c n. Show that exactly one of the following holds:
    1. y m s.t. AT y = c
    2. x n s.t. Ax = 0,cT x0.
    John Mitchell 518–276–6915
    Amos Eaton 325 mitchj at rpi dot edu
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