# \[AMPL 24675\] Decomposition solution
**URL:** https://discuss.ampl.com/t/ampl-24675-decomposition-solution/580
**Category:** Google Group Mirror
**Created:** [May 29, 2023, 11:27am UTC](https://discuss.ampl.com/t/ampl-24675-decomposition-solution/580 "2023-05-29T11:27:25Z")
**Posts on this page:** 2
**Page:** 1
### Author:  [@andrea\_rosa](https://discuss.ampl.com/u/andrea_rosa)
#### Post date: [May 29, 2023, 11:27am UTC](https://discuss.ampl.com/t/ampl-24675-decomposition-solution/580/1 "2023-05-29T11:27:25Z")
Hi everyone! i have a model with a set aircraft:={1…N}, which describe an aircraft landing problem. My objective is to decompose the problem into subproblems that are easier to solve individually. I want to create subsets of aircraft, solving smaller subproblems separately and then combining the solutions, reducing the overall computational complexity and obtain good solutions more quickly. To do this, i have implemented this algorithm which iteratively generates the subsets ‘aircraft-relaxed’ and, for each subset, solve the new model ALP\_red (this model is equal to the initial one, but instead of set aircraft, it uses set aircraft\_red, for each variables and constraints). The problem is that AMPL gives me an error if i put the model ALP\_red inside the for cycle. How can I solve this problem, in order to achieve my goal?
Attached the initial model ALP\_model, the new model ALP\_model\_red, and the file .run which represents my algorithm (decmat.run)
Thank you for your help!
Best regards, Andrea
[ALP\_model.mod](https://discuss.ampl.com/uploads/short-url/nkDs5H1w50qle7vuqg1N5tIwMuR.mod) (2 KB)
[alpdec.mod](https://discuss.ampl.com/uploads/short-url/oaW9SAk5dJjU1TYawW3r119Pb4V.mod) (2.29 KB)
[decmat.run](https://discuss.ampl.com/uploads/short-url/6KvO6qmrmLghb3UCSwapzK3e4GW.run) (1.45 KB)
---
### Author:  [@AMPL\_Google\_Group](https://discuss.ampl.com/u/AMPL_Google_Group)
#### Post date: [May 30, 2023, 3:53pm UTC](https://discuss.ampl.com/t/ampl-24675-decomposition-solution/580/2 "2023-05-30T15:53:22Z")
This question was answered in our [new user forum](https://discuss.ampl.com/t/decomposition-solution/578/2).