[Symphony] bicriteria operations

[S R]

I am trying to use the bicriteria optimization in symphony (version
5.2 or 5.1.10).  I am having trouble finding solutions and think I
must be fundmentally misunderstanding things.


After many attempts, here is what I think I have determined (examples from 5.2):

-- Setting the second objective coefficients equal to the first
objective coefficients, I am able to get a solution.

-- Setting the second objective coefficients equal to a small ( x 10 )
scalar multiple of the first objective coefficients, I am able to get
a solution.

-- Setting the second objective coefficients equal to a larger ( x 100
) scalar multiple of the first objective coefficients, I am NOT able
to get a solution.

-- Setting the second objective coefficients equal to 0, I am able to
get a solution.  (Seems to use normal branch and bound.)

-- Setting the second objective coefficients equal to 1, I am NOT able
to get a solution.

-- Setting the second objective coefficients to what I want them to
actually be, the runtime is much longer and I am NOT able to get a
solution.  I have not come up with any scalar multiplication of these
coefficients that make any different.


So, what am I missing?

1. Why do scalar multiplications make any difference?

2. How do I interpret the "Range: xxx to yyy" in the output?

3. Is there any documentation for this?  Or examples?


Thanks for any assistance.

Sam