# How use bounding restrictions in Baron

**URL:** <https://discuss.ampl.com/t/how-use-bounding-restrictions-in-baron/2096>\
**Category:** Support\
**Created:** [March 21, 2025, 10:12pm UTC](https://discuss.ampl.com/t/how-use-bounding-restrictions-in-baron/2096 "2025-03-21T22:12:55Z")\
**Posts on this page:** 2\
**Page:** 1

<div class="post-metadata">

**Author:** ![Gustavo\_Martinez](https://sea1.discourse-cdn.com/flex019/user_avatar/discuss.ampl.com/gustavo_martinez/32/642_2.png) [@Gustavo\_Martinez](https://discuss.ampl.com/u/Gustavo_Martinez)\
**Post date:** [March 21, 2025, 10:12pm UTC](https://discuss.ampl.com/t/how-use-bounding-restrictions-in-baron/2096/1 "2025-03-21T22:12:55Z")

</div>

_Hello, I’m trying to solve a nonlinear problem with Baron in NEOS. Without an optional bounding restriction, I get solutions. However, when I try to use it, I don’t get any solution. Any idea why this might happen?_

_The model is for a square packing problem, and the bounding restriction tries to limit the area of the box._

_Here’s the model:_  
[nero.run](https://discuss.ampl.com/uploads/short-url/grMxx5yyiOMIRPr6hTUfkRgy6Wq.run) (611 Bytes)  
[MGC.mod](https://discuss.ampl.com/uploads/short-url/nSLIT5nSafaoRbv5tfSpdRaleTW.mod) (2.3 KB)  
[MecfG.dat](https://discuss.ampl.com/uploads/short-url/xI3yvncS8X4ZmIU2Kjmj6jrqFNY.dat) (2.0 KB)

Best regards

---

<div class="post-metadata">

**Author:** ![4er](https://sea1.discourse-cdn.com/flex019/user_avatar/discuss.ampl.com/4er/32/530_2.png) [@4er](https://discuss.ampl.com/u/4er)\
**Post date:** [March 25, 2025, 10:00pm UTC](https://discuss.ampl.com/t/how-use-bounding-restrictions-in-baron/2096/2 "2025-03-25T22:00:47Z")

</div>

Here’s what I see when I run on NEOS with a time limit of 100 seconds. When the bounding restriction is not included, BARON’s preprocessing heuristics find a feasible solution with objective value 35.6983. The subsequent search does not find any better solution, so the feasible solution found by preprocessing is returned:

```auto
Doing local search
 Solving bounding LP
 Starting multi-start local search
 Preprocessing found feasible solution with value 35.6983
 Done with local search
===========================================================================
  Iteration Time (s) Mem Lower bound Upper bound Progress
          1 22.39 28MB 0.625000E-01 35.6983 0.02%
         15 54.65 28MB 0.625000E-01 35.6983 0.04%
        127 88.36 28MB 0.625000E-01 35.6983 0.05%
        382 100.02 37MB 0.625000E-01 35.6983 0.05%

                    ***Max. allowable time exceeded***   
.......

BARON 24.5.8 (2024.05.08): 382 iterations, CPU time limit reached.
Objective 35.69833937

```

When you add the bounding restriction,

```auto
s.t. tes4: (W)*(H)<=25.00;

```

the previous solution with objective value (W)\*(H) equal to 35.6983 is no longer feasible. Neither the preprocessing nor the search is able to find any feasible solution at all before BARON reaches the time limit:

```auto
 Doing local search
 Solving bounding LP
 Starting multi-start local search
 Done with local search
===========================================================================
  Iteration Time (s) Mem Lower bound Upper bound Progress
          1 47.02 28MB 0.625000E-01 0.100000E+52 NA
          3+ 80.26 28MB 0.625000E-01 0.100000E+52 NA
          4 100.01 28MB 0.625000E-01 25.0000 0.00%

                    ***Max. allowable time exceeded***     

                   ***No feasible solution was found***

```

Thus no solution is returned.

Since you are seeing the same behavior even with a much higher time limit, it may be that there is no feasible solution at all with (W)\*(H)\<=25.00. Or there may be a feasible solution satisfying this constraint, but it is very hard for BARON to find.