[AMPL 24888] What do i set U to?

I have attached 2 files. A .dat and .mod regarding a firehouse location.

I have put a new constraint in which is U. I wanted to know what do I set U to, in order to get a different output than just all 1’s(which is the original output) I will attach the initial .mod and .dat file too.

The originial is Firehouse
The one with the new constraint U is SAHC-hw7

Please let me know,

SAHC-hw7.mod (1.51 KB)

firehouse.mod (1.28 KB)

firehouse.dat (508 Bytes)

SAHC-hw7.dat (504 Bytes)

After solving the problem, have a look at the left and right sides of “sum{e in DSTRCTS} y[d,e] <= U”:

ampl: display {d in DSTRCTS} (sum{e in DSTRCTS} y[d,e]), U;
sum{e in DSTRCTS} y[d,e] [*] :=
A  2
B  0
C  0
D  0
E  3

U = 2850

You can see that this constraint is not having any effect, because the value of param U is much larger than the optimal values of sum{e in DSTRCTS} y[d,e]. To make any difference to the solution, you will need to set U to be smaller than at least one of the values of sum{e in DSTRCTS} y[d,e].

The two “display” statements at the end of firehouse.mod and SAHC-hw7.mod are only displaying the values of x[d] and y[d,e] that are > 0 – so necessarily the output is all 1’s. If instead you write “display x, y;” then you will see both 0 and 1 values.